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1.  Effectiveness of the Standard WHO Recommended Retreatment Regimen (Category II) for Tuberculosis in Kampala, Uganda: A Prospective Cohort Study 
PLoS Medicine  2011;8(3):e1000427.
Prospective evaluation of the effectiveness of the WHO-recommended standardized retreatment regimen for tuberculosis by Edward Jones-López and colleagues reveals an unacceptable proportion of unsuccessful outcomes.
Background
Each year, 10%–20% of patients with tuberculosis (TB) in low- and middle-income countries present with previously treated TB and are empirically started on a World Health Organization (WHO)-recommended standardized retreatment regimen. The effectiveness of this retreatment regimen has not been systematically evaluated.
Methods and Findings
From July 2003 to January 2007, we enrolled smear-positive, pulmonary TB patients into a prospective cohort to study treatment outcomes and mortality during and after treatment with the standardized retreatment regimen. Median time of follow-up was 21 months (interquartile range 12–33 months). A total of 29/148 (20%) HIV-uninfected and 37/140 (26%) HIV-infected patients had an unsuccessful treatment outcome. In a multiple logistic regression analysis to adjust for confounding, factors associated with an unsuccessful treatment outcome were poor adherence (adjusted odds ratio [aOR] associated with missing half or more of scheduled doses 2.39; 95% confidence interval (CI) 1.10–5.22), HIV infection (2.16; 1.01–4.61), age (aOR for 10-year increase 1.59; 1.13–2.25), and duration of TB symptoms (aOR for 1-month increase 1.12; 1.04–1.20). All patients with multidrug-resistant TB had an unsuccessful treatment outcome. HIV-infected individuals were more likely to die than HIV-uninfected individuals (p<0.0001). Multidrug-resistant TB at enrolment was the only common risk factor for death during follow-up for both HIV-infected (adjusted hazard ratio [aHR] 17.9; 6.0–53.4) and HIV-uninfected (14.7; 4.1–52.2) individuals. Other risk factors for death during follow-up among HIV-infected patients were CD4<50 cells/ml and no antiretroviral treatment (aHR 7.4, compared to patients with CD4≥200; 3.0–18.8) and Karnofsky score <70 (2.1; 1.1–4.1); and among HIV-uninfected patients were poor adherence (missing half or more of doses) (3.5; 1.1–10.6) and duration of TB symptoms (aHR for a 1-month increase 1.9; 1.0–3.5).
Conclusions
The recommended regimen for retreatment TB in Uganda yields an unacceptable proportion of unsuccessful outcomes. There is a need to evaluate new treatment strategies in these patients.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
One-third of the world's population is currently infected with Mycobacterium tuberculosis, the bacterium that causes tuberculosis (TB), and 5%–10% of HIV-uninfected individuals will go on to develop disease and become infectious. The risk of progression from infection to disease in HIV infected is much higher. If left untreated, each person with active TB may infect 10 to 15 people every year, reinforcing the public health priority of controlling TB through adequate treatment. Patients with a previous history of TB treatment are a major concern for TB programs throughout the world because these patients are at a much higher risk of harboring a form of TB that is resistant to the drugs most frequently used, resulting in poorer treatment outcomes and significantly complicating current management strategies. More then 1 million people in over 90 countries need to be “re-treated” after failing, interrupting, or relapsing from previous TB treatment.
Every year, 10%–20% of people with TB in low- and middle-income countries are started on a standardized five-drug retreatment regimen as recommended by the World Health Organization (WHO). Yet, unlike treatment regimens for newly diagnosed TB patients, the recommended retreatment regimen (also known as the category II regimen) has never been properly evaluated in randomized clinical trials or prospective cohort studies. Rather, this regimen was recommended by experts before the current situation of widespread drug-resistant TB and HIV infection.
Why Was This Study Done?
WHO surveillance data suggest that the retreatment regimen is successful in about 70% of patients, but retrospective studies that have evaluated the regimen's efficacy showed variable treatment responses with success rates ranging from 26% to 92%. However, these studies have generally only assessed outcomes at the completion of the retreatment regimen, and few have examined the risk of TB recurrence, especially in people who are also infected with HIV and so are more likely to experience TB recurrence—an issue of particular concern in sub-Saharan Africa. Therefore, in this study based in Kampala, Uganda, the researchers conducted a prospective cohort study to assess treatment and survival outcomes in patients previously treated for TB and to identify factors associated with poor outcomes. Given the overwhelming contribution of HIV infection to death, the researchers categorized their survival analysis by HIV status.
What Did the Researchers Do and Find?
The researchers recruited consecutive smear-positive TB patients who were admitted to Mulago Hospital, Kampala, Uganda, for the retreatment of TB with the standard retreatment regimen between July 2003 and January 2007. Eligible patients received daily directly observed therapy and after hospital discharge, were seen every month during their 8-month TB-retreatment course. Home health visitors assessed treatment adherence through treatment card review, monthly pill counts, and patient self-report. After the completion of the retreatment regimen, patients were evaluated for TB recurrence every 3 months for a median of 21 months. The researchers then used a statistical model to identify treatment outcomes and mortality HIV-uninfected and HIV-infected patients.
The researchers found that 29/148 (20%) of HIV-uninfected and 37/140 (26%) of HIV-infected patients had an unsuccessful treatment outcome. Factors associated with an unsuccessful treatment outcome were poor adherence, HIV infection, increasing age, and duration of TB symptoms. All patients with multidrug resistant TB, a form of TB that is resistant to the two most important drugs used to treat TB, had an unsuccessful treatment outcome. In addition, HIV-infected subjects were more likely to die than HIV-uninfected subjects (p<0.0001), and having multidrug resistant TB at enrollment was the only common risk factor for death during follow-up for both HIV-infected and HIV uninfected patients. Other risk factors for death among HIV-infected patients were CD4<50 cells/ml and no antiretroviral therapy treatment and among HIV-uninfected patients were poor adherence and duration of TB symptoms.
What Do These Findings Mean?
The researchers found that although 70%–80% of patients had a successful treatment outcome on completion of antituberculous therapy (a result that compares well with retrospective studies), the standard retreatment regimen had low treatment response rates and was associated with poor long-term outcomes in certain subgroups of patients, particularly those with multidrug resistant TB and HIV.
These findings indicate that the standard retreatment approach to TB as implemented in low- and middle-income settings is inadequate and stress the importance of a new, more effective, strategies. Improved access to rapid diagnostics for TB drug-resistance, second-line TB treatment, and antiretroviral therapy is urgently needed, along with a strong evidence base to guide clinicians and policy makers on how best to use these tools.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000427.
The World Health Organization has information on TB, TB retreatment, and multidrug-resistant TB
WHO also provides information on TB/HIV coinfection
The Stop TB Partnership provides information on the global plan to stop TB
doi:10.1371/journal.pmed.1000427
PMCID: PMC3058098  PMID: 21423586
2.  Rates and risk factors for drug resistance tuberculosis in Northeastern China 
BMC Public Health  2013;13:1171.
Background
Drug-resistant tuberculosis (TB) has emerged as a major challenge toward TB control and prevention. In Lianyungang city, the extent and trend of drug resistant TB is not well known. The objective of the survey was to assess drug resistance pattern of MTB and risk factors for drug resistant TB, including multidrug resistance tuberculosis (MDR-TB) in this area.
Methods
We performed drug susceptibility testing on Mycobacterium tuberculosis (MTB) isolates with first- and second-line anti-tuberculosis drugs of 1012 culture positive TB cases by using the proportion method, who were consecutively enrolled from January 2011 to December 2012 in Lianyungang city, China. The patterns of drug resistance in MTB were investigated and multiple logistic regression analysis was performed to assess the risk factors for drug resistant TB.
Results
Among the 1012 strains tested, 308 (30.4%) strains were resistant to at least one first-line drug; the prevalence of MDR-TB was 88 (8.7%), 5 (0.5%) strains were found to be extensively drug-resistant tuberculosis (XDR-TB). Female gender was a risk factor for MDR-TB (adjusted odds ratio (aOR) 1.763, 95% CI (1.060-2.934). The aged 28–54 years was significantly associated with the risk of MDR-TB with an aOR: 2.224, 95% CI (1.158-4.273) when compared with those 65 years or older. Patients with previous treatment history had a more than 7-fold increased risk of MDR-TB, compared with those never previously treated.
Conclusions
The burden of drug resistant TB cases is sizeable, which highlights an urgent need to reinforce control, detection and treatment strategies for drug resistant TB.
doi:10.1186/1471-2458-13-1171
PMCID: PMC3878749  PMID: 24330553
Epidemiology; MDR-TB; Drug resistance; Drug susceptibility
3.  Epidemiology of anti-tuberculosis drug resistance in a chinese population: current situation and challenges ahead 
BMC Public Health  2011;11:110.
Background
Drug resistance has been a cause of concern for tuberculosis (TB) control in both developed and developing countries. Careful monitoring of the patterns and trends of drug resistance should remain a priority.
Methods
Strains were collected from 1824 diagnosed sputum smear positive pulmonary TB patients in Jiangsu province of China and then tested for drug susceptibility against rifampicin, isoniazid, ethambutol and streptomycin. The prevalence and patterns of drug resistance in mycobacterium tuberculosis (MTB) isolates were investigated. Multiple logistic regression analysis was performed to identify the risk factors for multidrug resistant (MDR) bacterial infection. The strength of association was estimated by odds ratio (OR) and 95% confidence interval (95% CI).
Results
The drug susceptibility tests showed that 1077(59.05%) MTB strains were sensitive to all the four antibiotics and the other 747(40.95%) strains were resistant to at least one drug. The proportions of mono-drug resistance were 28.73% for isoniazid, 19.41% for rifampicin, 29.33% for streptomycin, and 13.98% for ethambutol, respectively. The prevalence of MDR-TB was 16.61%, which was significantly different between new cases (7.63%) and those with previous treatment history (33.07%). Geographical variation of drug resistance was observed, where the proportion of MDR-TB among new cases was higher in the central (9.50%) or north part (9.57%) than that in the south area (4.91%) of Jiangsu province. The age of patients was significantly associated with the risk of drug resistance (P < 0.001) and the adjusted OR (95% CI) was 1.88(1.26-2.81) for patients aged 35-44 years when compared with those 65 years or older. Patients with previous treatment history had a more than 5-fold increased risk of MDR-TB (adjusted OR: 6.14, 95% CI: 4.61-8.17), compared with those previously not having been treated.
Conclusions
The high prevalence of drug resistance has been a major challenge for TB control. Prevention and control of drug-resistant TB should be emphasized by the revised DOTS (direct observed therapy, short course) program through prompt case detection, routine and quality-assured drug susceptibility test for patients at high risk of resistance, programmatic treatment with both first and second-line medicines, and systematic treatment observation, with priority for high MDR-TB settings.
doi:10.1186/1471-2458-11-110
PMCID: PMC3045946  PMID: 21324205
4.  Tuberculosis risk factors among tuberculosis patients in Kampala, Uganda: implications for tuberculosis control 
BMC Public Health  2015;15:13.
Background
Slow decline in the incidence of tuberculosis (TB) has been observed in most high TB burden countries. Knowledge of the prevalence of different TB risk factors can help expand TB control strategies. However with the exception of Human Immunodeficiency Virus (HIV) the prevalence of the other TB risk factors are poorly studied in Uganda. We aimed to determine the prevalence of different TB risk factors and TB disease presentation among TB patients in Kampala Uganda.
Methods
We assessed 365 adult TB patients and used descriptive statistics to summarize their socio-demographic, clinical, radiological, sputum mycobacteriology and TB risk factors (HIV, diabetes, TB contact, alcohol use, tobacco smoking, poverty and overcrowding) data.
Results
A total of 158 (43.3%) patients were male and the median age was 29 (IQR 28–30). Majority of the patients (89.2%) had pulmonary TB, 86.9% were new and 13.2% were retreatment. Wasting (i.e. body mass index of <18.5 kg/m2) was found in 38.5% of the patients and 63% presented with cough. Constitutional symptoms (fever, anorexia, night sweats and weight loss) were reported by 32.1%. Most patients (78.6%) presented with non-cavity lung parenchyma disease (infiltrates, nodules, masses) but 35.2% had cavity disease. Pleural disease was detected in 19.3% of patients. Positive smear microscopy and culture (irrespective of month of treatment) was found in 52.7% and 36.5% of patients respectively. Any drug resistance was detected in 21.1% of patients while multidrug resistance (MDR) TB defined as resistance to rifampicin and isoniazid was detected in 6.3% of patients. All MDR patients were new patients.
The prevalence of TB risk factors were as follows: HIV 41.4%, diabetes 5.4%, close contact 11.5%, family history 17.5%, smoking 26.37%, poverty 39.5%, overcrowding 57.3% and alcohol use 50.7%. Overcrowding increased smear positive rate, prevalence ratio 1.22, p = 0.09 but all the other studied risk factors did not affect clinical, radiological and mycobacteriological study patient characteristics.
Conclusions
Among TB patients in Kampala, Uganda, there is high prevalence of the known TB risk factors. Targeting reducing their prevalence may lead to better TB control in the country. Tuberculosis, risk factors, Uganda.
doi:10.1186/s12889-015-1376-3
PMCID: PMC4311451  PMID: 25604986
5.  Anti-Tuberculosis Drug Resistance among New and Previously Treated Sputum Smear-Positive Tuberculosis Patients in Uganda: Results of the First National Survey 
PLoS ONE  2013;8(8):e70763.
Background
Multidrug resistant and extensively drug resistant tuberculosis (TB) have become major threats to control of tuberculosis globally. The rates of anti-TB drug resistance in Uganda are not known. We conducted a national drug resistance survey to investigate the levels and patterns of resistance to first and second line anti-TB drugs among new and previously treated sputum smear-positive TB cases.
Methods
Sputum samples were collected from a nationally representative sample of new and previously treated sputum smear-positive TB patients registered at TB diagnostic centers during December 2009 to February 2011 using a weighted cluster sampling method. Culture and drug susceptibility testing was performed at the national TB reference laboratory.
Results
A total of 1537 patients (1397 new and 140 previously treated) were enrolled in the survey from 44 health facilities. HIV test result and complete drug susceptibility testing (DST) results were available for 1524 (96.8%) and 1325 (85.9%) patients, respectively. Of the 1209 isolates from new cases, resistance to any anti-TB drug was 10.3%, 5% were resistant to isoniazid, 1.9% to rifampicin, and 1.4% were multi drug resistant. Among the 116 isolates from previously treated cases, the prevalence of resistance was 25.9%, 23.3%, 12.1% and 12.1% respectively. Of the 1524 patients who had HIV testing 469 (30.7%) tested positive. There was no association between anti-TB drug resistance (including MDR) and HIV infection.
Conclusion
The prevalence of anti-TB drug resistance among new patients in Uganda is low relative to WHO estimates. The higher levels of MDR-TB (12.1%) and resistance to any drug (25.3%) among previously treated patients raises concerns about the quality of directly observed therapy (DOT) and adherence to treatment. This calls for strengthening existing TB control measures, especially DOT, routine DST among the previously treated TB patients or periodic drug resistance surveys, to prevent and monitor development and transmission of drug resistant TB.
doi:10.1371/journal.pone.0070763
PMCID: PMC3731251  PMID: 23936467
6.  Predictors of Multidrug- and Extensively Drug-Resistant Tuberculosis in a High HIV Prevalence Community 
PLoS ONE  2010;5(12):e15735.
Background
Multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) have emerged in high-HIV-prevalence settings, which generally lack laboratory infrastructure for diagnosing TB drug resistance. Even where available, inherent delays with current drug-susceptibility testing (DST) methods result in clinical deterioration and ongoing transmission of MDR and XDR-TB. Identifying clinical predictors of drug resistance may aid in risk stratification for earlier treatment and infection control.
Methods
We performed a retrospective case-control study of patients with MDR (cases), XDR (cases) and drug-susceptible (controls) TB in a high-HIV-prevalence setting in South Africa to identify clinical and demographic risk factors for drug-resistant TB. Controls were selected in a 1∶1∶1 ratio and were not matched. We calculated odds ratios (OR) and performed multivariate logistic regression to identify independent predictors.
Results
We enrolled 116, 123 and 139 patients with drug-susceptible, MDR, and XDR-TB. More than 85% in all three patient groups were HIV-infected. In multivariate analysis, MDR and XDR-TB were each strongly associated with history of TB treatment failure (adjusted OR 51.7 [CI 6.6-403.7] and 51.5 [CI 6.4–414.0], respectively) and hospitalization more than 14 days (aOR 3.8 [CI 1.1–13.3] and 6.1 [CI 1.8–21.0], respectively). Prior default from TB treatment was not a risk factor for MDR or XDR-TB. HIV was a risk factor for XDR (aOR 8.2, CI 1.3–52.6), but not MDR-TB. Comparing XDR with MDR-TB patients, the only significant risk factor for XDR-TB was HIV infection (aOR 5.3, CI 1.0–27.6).
Discussion
In this high-HIV-prevalence and drug-resistant TB setting, a history of prolonged hospitalization and previous TB treatment failure were strong risk factors for both MDR and XDR-TB. Given high mortality observed among patients with HIV and drug-resistant TB co-infection, previously treated and hospitalized patients should be considered for empiric second-line TB therapy while awaiting confirmatory DST results in settings with a high-burden of MDR/XDR-TB.
doi:10.1371/journal.pone.0015735
PMCID: PMC3012092  PMID: 21209951
7.  Cost-Effectiveness of Treating Multidrug-Resistant Tuberculosis 
PLoS Medicine  2006;3(7):e241.
Background
Despite the existence of effective drug treatments, tuberculosis (TB) causes 2 million deaths annually worldwide. Effective treatment is complicated by multidrug-resistant TB (MDR TB) strains that respond only to second-line drugs. We projected the health benefits and cost-effectiveness of using drug susceptibility testing and second-line drugs in a lower-middle-income setting with high levels of MDR TB.
Methods and Findings
We developed a dynamic state-transition model of TB. In a base case analysis, the model was calibrated to approximate the TB epidemic in Peru, a setting with a smear-positive TB incidence of 120 per 100,000 and 4.5% MDR TB among prevalent cases. Secondary analyses considered other settings. The following strategies were evaluated: first-line drugs administered under directly observed therapy (DOTS), locally standardized second-line drugs for previously treated cases (STR1), locally standardized second-line drugs for previously treated cases with test-confirmed MDR TB (STR2), comprehensive drug susceptibility testing and individualized treatment for previously treated cases (ITR1), and comprehensive drug susceptibility testing and individualized treatment for all cases (ITR2). Outcomes were costs per TB death averted and costs per quality-adjusted life year (QALY) gained. We found that strategies incorporating the use of second-line drug regimens following first-line treatment failure were highly cost-effective compared to strategies using first-line drugs only. In our base case, standardized second-line treatment for confirmed MDR TB cases (STR2) had an incremental cost-effectiveness ratio of $720 per QALY ($8,700 per averted death) compared to DOTS. Individualized second-line drug treatment for MDR TB following first-line failure (ITR1) provided more benefit at an incremental cost of $990 per QALY ($12,000 per averted death) compared to STR2. A more aggressive version of the individualized treatment strategy (ITR2), in which both new and previously treated cases are tested for MDR TB, had an incremental cost-effectiveness ratio of $11,000 per QALY ($160,000 per averted death) compared to ITR1. The STR2 and ITR1 strategies remained cost-effective under a wide range of alternative assumptions about treatment costs, effectiveness, MDR TB prevalence, and transmission.
Conclusions
Treatment of MDR TB using second-line drugs is highly cost-effective in Peru. In other settings, the attractiveness of strategies using second-line drugs will depend on TB incidence, MDR burden, and the available budget, but simulation results suggest that individualized regimens would be cost-effective in a wide range of situations.
Editors' Summary
  Background.
Tuberculosis (TB) remains one of the most entrenched diseases on the planet—an estimated one in three people worldwide are infected with Mycobacterium tuberculosis, which causes the disease. Although effective drugs exist, a major reason for the failure to stem the spread of TB lies in the rise of drug-resistant strains of the bacterium. Some strains are resistant to several drugs; patients with this sort of infection are said to have multidrug-resistant (MDR) TB. The development of drug-resistant strains is fostered when health-care workers do not follow treatment guidelines or fail to ensure that patients take the whole treatment course. The World Health Organization recommends an approach to TB control called “DOTS,” which has been adopted by many countries. (See the link below for an explanation of what DOTS involves.) The antibiotics that are used in DOTS are described as “first-line” treatment drugs. They are highly effective against non-resistant TB but much less so against MDR TB. There are other, more expensive, “second-line” antibiotics that perform better against MDR TB.
  Why Was This Study Done?
Despite the worrying rise in MDR TB cases, the much higher cost of using second-line drugs is prompting some policy-makers to question the merits of introducing them in poor countries with limited resources. However, with MDR TB accounting for nearly a third of TB cases in some countries, first-line therapies seem unlikely to be sufficient in the long term. Second-line strategies, or “DOTS-Plus” strategies, are either standardized for a particular region or are chosen for individual patients on the basis of drug susceptibility tests. The researchers wanted to investigate whether standardized or individualized second-line regimens could save lives and be cost-effective in poor countries.
  What Did the Researchers Do and Find?
The researchers used a method called modeling. They took information already available about TB in Peru, where for every 100,000 people there are 120 new TB infections every year, and 4.5% of existing cases are MDR TB. The researchers then calculated what might happen over the next 30 years, comparing the likely effects of five alternative strategies. In four, new cases were given first-line drugs for 6 months. Those who were not cured were then treated in different ways. In DOTS, they were retreated with a second course of the same drugs; in STR1 they were given an 18-month standardized course of second-line and first-line drugs; in STR2, only confirmed MDR TB patients were given an 18-month standardized course of second-line and first-line drugs; and in ITR1, confirmed MDR TB patients were given a personalized regimen of second-line drugs. The fifth strategy, ITR2, tested all patients for drug susceptibility at the outset of treatment, and those with MDR TB were given an individualized course; those not cured were tested again and given another individualized course.
  Compared with DOTS, both the STR1 and STR2 strategies averted 4.8 deaths per 100,000 population, at a cost of $8,700 per averted death—with STR2 being a better value for money since it treated only confirmed MDR TB cases with the more expensive, second-line drugs. Of the individualized treatments, ITR1 averted an extra 0.9 deaths at a cost of $12,000 per averted death; ITR2 averted a further 1.2 deaths but at a much higher $160,000 per saved life.
  What Do These Findings Mean?
Despite the slightly higher cost of ITR1, the extra number of lives it would save compared with STR2 makes it a good approach for treatment in Peru. However, cost-effectiveness varies with other factors. If the difference in cost between the two strategies became higher than $9,500 per patient, STR would be preferable. And, if MDR TB were present in 10% of all TB cases, ITR2—with comprehensive drug susceptibility testing for all TB patients—would be best.
  The findings are of interest not just in Peru but in other developing countries where MDR TB is a growing problem. The researchers maintain that, in areas where DOTS has not yet been fully implemented, it would be more efficient to expand DOTS than to introduce DOTS-Plus. But they add that it would be beneficial to expand DOTS as well as implement DOTS-Plus. Individualized treatment after drug susceptibility testing is likely to be cost-effective even in the poorest of countries, which should give impetus to governments and organizations in those countries where MDR TB is a growing concern to modify their approach to treatment.
  Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0030241.
• Basic information about tuberculosis can be found on the Web site of the US National Institute of Allergy and Infectious Diseases
• The Web site of the World Health Organization's Stop TB department outlines both the DOTS and DOTS-Plus strategies
•  TB Alert, a UK-based charity that promotes TB awareness worldwide, has information on TB in several European, African, and Asian languages
Resch and colleagues found that treatment of MDR TB using second-line drugs is highly cost-effective in Peru.
doi:10.1371/journal.pmed.0030241
PMCID: PMC1483913  PMID: 16796403
8.  Prevalence of multidrug resistance in Mycobacterium tuberculosis isolates from HIV seropositive and seronegative patients with pulmonary tuberculosis in north India 
BMC Infectious Diseases  2013;13:137.
Background
Multidrug resistant (MDR) and extensively-drug resistant (XDR) tuberculosis (TB) are a serious threat to the national TB control programs of developing countries, and the situation is further worsened by the human immunodeficiency virus (HIV) pandemic. The literature regarding MDR/XDR-TB is, however, scanty from most parts of India. We carried out this study to assess the prevalence of MDR/XDR-TB in new and previously treated cases of pulmonary TB and in HIV seropositive and seronegative patients.
Methods
Sputum and blood specimens were obtained from 2100 patients suspected of pulmonary tuberculosis and subjected to sputum microscopy and culture for TB, and HIV serology at our tertiary care centre in north India. The culture positive Mycobacterium tuberculosis isolates were subjected to drug susceptibility testing (DST) for first line anti-tuberculosis drugs, and the MDR isolates were further subjected to second line DST. Various parameters of the patients’ were analyzed viz. clinical presentation, radiology, previous treatment history, demographic and socioeconomic data and microbiology results.
Results
Of the 2100 patients, sputum specimens of 256 were smear positive for acid-fast bacilli (AFB), 271 (12.9%) grew Mycobacterium spp., and M. tuberculosis was isolated in 219 (10.42%). Of the 219 patients infected with M. tuberculosis, 20.1% (44/219) were found to be seropositive for HIV. Overall, MDR-TB was observed in 17.4% (39/219) isolates. There were 121 newly diagnosed and 98 previously treated patients, of which MDR-TB was found to be associated with 9.9% (12/121) and 27.6% (27/98) cases respectively. There was significantly higher association of MDR-TB (12/44, 27.3%) with HIV seropositive patients as compared to HIV seronegative patients (27/175, 15.4%) after controlling previous treatment status, age, and sex (odd’s ratio, 2.3 [95% CI, 1.000-5.350]; p-value, 0.05). No XDR-TB was found among the MDR-TB isolates.
Conclusion
The present study demonstrated a high prevalence of drug resistance amongst pulmonary TB isolates of M. tuberculosis from north India as compared to the WHO estimates for India in 2010, though this could possibly be attributed to the clustering of more serious or referred cases at our tertiary care centre. The prevalence of MDR-TB in HIV seropositive patients was significantly higher than seronegative individuals. The study emphasizes the need to monitor the trends of drug resistance in TB in various populations in order to timely implement appropriate interventions to curb the menace of MDR-TB.
doi:10.1186/1471-2334-13-137
PMCID: PMC3610146  PMID: 23497169
Mycobacterium tuberculosis; Multidrug resistant; Extensively-drug resistant; HIV; Socioeconomic status
9.  Rates of Anti-Tuberculosis Drug Resistance in Kampala-Uganda Are Low and Not Associated with HIV Infection 
PLoS ONE  2011;6(1):e16130.
Background
Drug resistance among tuberculosis patients in sub-Saharan Africa is increasing, possibly due to association with HIV infection. We studied drug resistance and HIV infection in a representative sample of 533 smear-positive tuberculosis patients diagnosed in Kampala, Uganda.
Methods/Principal Findings
Among 473 new patients, multidrug resistance was found in 5 (1.1%, 95% CI 0.3–2.5) and resistance to any drug in 57 (12.1%, 9.3–15.3). Among 60 previously treated patients this was 7 (11.7%, 4.8–22.6) and 17 (28.3%; 17.5–41.4), respectively. Of 517 patients with HIV results, 165 (31.9%, 27.9–36.1) tested positive. Neither multidrug (adjusted odds ratio (ORadj) 0.7; 95% CI 0.19–2.6) nor any resistance (ORadj 0.7; 0.43–1.3) was associated with HIV status. Primary resistance to any drug was more common among patients who had worked in health care (ORadj 3.5; 1.0–12.0).
Conclusion/Significance
Anti-tuberculosis drug resistance rates in Kampala are low and not associated with HIV infection, but may be associated with exposure during health care.
doi:10.1371/journal.pone.0016130
PMCID: PMC3018425  PMID: 21249225
10.  Tuberculosis in Sudan: a study of Mycobacterium tuberculosis strain genotype and susceptibility to anti-tuberculosis drugs 
BMC Infectious Diseases  2011;11:219.
Background
Sudan is a large country with a diverse population and history of civil conflict. Poverty levels are high with a gross national income per capita of less than two thousand dollars. The country has a high burden of tuberculosis (TB) with an estimated 50,000 incident cases during 2009, when the estimated prevalence was 209 cases per 100,000 of the population. Few studies have been undertaken on TB in Sudan and the prevalence of drug resistant disease is not known.
Methods
In this study Mycobacterium tuberculosis isolates from 235 patients attending three treatment centers in Sudan were screened for susceptibility to isoniazid, rifampicin, ethambutol and streptomycin by the proportion method on Lowenstein Jensen media. 232 isolates were also genotyped by spoligotyping. Demographic details of patients were recorded using a structured questionnaire. Statistical analyses were conducted to examine the associations between drug resistance with risk ratios computed for a set of risk factors (gender, age, case status - new or relapse, geographic origin of the patient, spoligotype, number of people per room, marital status and type of housing).
Results
Multi drug-resistant tuberculosis (MDR-TB), being resistance to at least rifampicin and isoniazid, was found in 5% (95% CI: 2,8) of new cases and 24% (95% CI: 14,34) of previously treated patients. Drug resistance was associated with previous treatment with risk ratios of 3.51 (95% CI: 2.69-4.60; p < 0.001) for resistance to any drug and 5.23 (95% CI: 2.30-11.90; p < 0.001) for MDR-TB. Resistance was also associated with the geographic region of origin of the patient, being most frequently observed in patients from the Northern region and least in the Eastern region with risk ratios of 7.43 (95%CI:3.42,16.18; p: < 0.001) and 14.09 (95%CI:1.80,110.53; p:0.026) for resistance to any drug and MDR-TB. The major genotype observed was of the Central Asia spoligotype family (CAS1_Delhi), representing 49% of the 232 isolates examined.
Conclusions
We conclude that emergence of drug resistant tuberculosis has the potential to be a serious public health problem in Sudan and that strengthened tuberculosis control and improved monitoring of therapy is needed. Further surveillance is required to fully ascertain the extent of the problem.
doi:10.1186/1471-2334-11-219
PMCID: PMC3166935  PMID: 21846389
11.  Multidrug Resistant Pulmonary Tuberculosis Treatment Regimens and Patient Outcomes: An Individual Patient Data Meta-analysis of 9,153 Patients 
Ahuja, Shama D. | Ashkin, David | Avendano, Monika | Banerjee, Rita | Bauer, Melissa | Bayona, Jamie N. | Becerra, Mercedes C. | Benedetti, Andrea | Burgos, Marcos | Centis, Rosella | Chan, Eward D. | Chiang, Chen-Yuan | Cox, Helen | D'Ambrosio, Lia | DeRiemer, Kathy | Dung, Nguyen Huy | Enarson, Donald | Falzon, Dennis | Flanagan, Katherine | Flood, Jennifer | Garcia-Garcia, Maria L. | Gandhi, Neel | Granich, Reuben M. | Hollm-Delgado, Maria G. | Holtz, Timothy H. | Iseman, Michael D. | Jarlsberg, Leah G. | Keshavjee, Salmaan | Kim, Hye-Ryoun | Koh, Won-Jung | Lancaster, Joey | Lange, Christophe | de Lange, Wiel C. M. | Leimane, Vaira | Leung, Chi Chiu | Li, Jiehui | Menzies, Dick | Migliori, Giovanni B. | Mishustin, Sergey P. | Mitnick, Carole D. | Narita, Masa | O'Riordan, Philly | Pai, Madhukar | Palmero, Domingo | Park, Seung-kyu | Pasvol, Geoffrey | Peña, Jose | Pérez-Guzmán, Carlos | Quelapio, Maria I. D. | Ponce-de-Leon, Alfredo | Riekstina, Vija | Robert, Jerome | Royce, Sarah | Schaaf, H. Simon | Seung, Kwonjune J. | Shah, Lena | Shim, Tae Sun | Shin, Sonya S. | Shiraishi, Yuji | Sifuentes-Osornio, José | Sotgiu, Giovanni | Strand, Matthew J. | Tabarsi, Payam | Tupasi, Thelma E. | van Altena, Robert | Van der Walt, Martie | Van der Werf, Tjip S. | Vargas, Mario H. | Viiklepp, Pirett | Westenhouse, Janice | Yew, Wing Wai | Yim, Jae-Joon
PLoS Medicine  2012;9(8):e1001300.
Dick Menzies and colleagues report findings from a collaborative, individual patient-level meta-analysis of treatment outcomes among patients with multidrug-resistant tuberculosis.
Background
Treatment of multidrug resistant tuberculosis (MDR-TB) is lengthy, toxic, expensive, and has generally poor outcomes. We undertook an individual patient data meta-analysis to assess the impact on outcomes of the type, number, and duration of drugs used to treat MDR-TB.
Methods and Findings
Three recent systematic reviews were used to identify studies reporting treatment outcomes of microbiologically confirmed MDR-TB. Study authors were contacted to solicit individual patient data including clinical characteristics, treatment given, and outcomes. Random effects multivariable logistic meta-regression was used to estimate adjusted odds of treatment success. Adequate treatment and outcome data were provided for 9,153 patients with MDR-TB from 32 observational studies. Treatment success, compared to failure/relapse, was associated with use of: later generation quinolones, (adjusted odds ratio [aOR]: 2.5 [95% CI 1.1–6.0]), ofloxacin (aOR: 2.5 [1.6–3.9]), ethionamide or prothionamide (aOR: 1.7 [1.3–2.3]), use of four or more likely effective drugs in the initial intensive phase (aOR: 2.3 [1.3–3.9]), and three or more likely effective drugs in the continuation phase (aOR: 2.7 [1.7–4.1]). Similar results were seen for the association of treatment success compared to failure/relapse or death: later generation quinolones, (aOR: 2.7 [1.7–4.3]), ofloxacin (aOR: 2.3 [1.3–3.8]), ethionamide or prothionamide (aOR: 1.7 [1.4–2.1]), use of four or more likely effective drugs in the initial intensive phase (aOR: 2.7 [1.9–3.9]), and three or more likely effective drugs in the continuation phase (aOR: 4.5 [3.4–6.0]).
Conclusions
In this individual patient data meta-analysis of observational data, improved MDR-TB treatment success and survival were associated with use of certain fluoroquinolones, ethionamide, or prothionamide, and greater total number of effective drugs. However, randomized trials are urgently needed to optimize MDR-TB treatment.
Please see later in the article for the Editors' Summary.
Editors' Summary
Background
In 2010, 8.8 million people developed tuberculosis—a contagious bacterial infection—and 1.4 million people died from the disease. Mycobacterium tuberculosis, the bacterium that causes tuberculosis, is spread in airborne droplets when people with the disease cough or sneeze and usually infects the lungs (pulmonary tuberculosis). The characteristic symptoms of tuberculosis are a persistent cough, weight loss, and night sweats. Tuberculosis can be cured by taking several powerful antibiotics regularly for at least 6 months. The standard treatment for tuberculosis comprises an initial intensive phase lasting 2 months during which four antibiotics are taken daily followed by a 4-month continuation phase during which two antibiotics are taken. However, global efforts to control tuberculosis are now being thwarted by the emergence of M. tuberculosis strains that are resistant to several antibiotics, including isoniazid and rifampicin, the two most powerful, first-line (standard) anti-tuberculosis drugs.
Why Was This Study Done?
Although multi-drug resistant tuberculosis (MDR-TB) can be cured using second-line anti-tuberculosis drugs, these are more expensive and more toxic than first-line drugs and optimal treatment regimens for MDR-TB have not been determined. Notably, there have been no randomized controlled trials of treatments for MDR-TB. Such trials, which compare outcomes (cure, treatment failure, relapse, and death) among patients who have been randomly assigned to receive different treatments, are the best way to compare different anti-tuberculosis drug regimens. It is possible, however, to get useful information about the association of various treatments for MDR-TB with outcomes from observational studies using a statistical approach called “individual patient data meta-analysis.” In observational studies, because patients are not randomly assigned to different treatments, differences in outcomes between treatment groups may not be caused by the different drugs they receive but may be due to other differences between the groups. An individual patient data meta-analysis uses statistical methods to combine original patient data from several different studies. Here, the researchers use this approach to investigate the association of specific drugs, numbers of drugs and treatment duration with the clinical outcomes of patients with pulmonary MDR-TB.
What Did the Researchers Do and Find?
The researchers used three recent systematic reviews (studies that use predefined criteria to identify all the research on a given topic) to identify studies reporting treatment outcomes of microbiologically confirmed MDR-TB. They obtained individual patient data from the authors of these studies and estimated adjusted odds (chances) of treatment success from the treatment and outcome data of 9,153 patients with MDR-TB provided by 32 centers. The use of later generation quinolones, ofloxacin, and ethionamide/prothionamide as part of multi-drug regimens were all associated with treatment success compared to failure, relapse or death, as were the use of four or more likely effective drugs (based on drug susceptibility testing of mycobacteria isolated from study participants) during the initial intensive treatment phase and the use of three or more likely effective drugs during the continuation phase. The researchers also report that among patients who did not die or stop treatment, the chances of treatment success increased with the duration of the initial treatment phase up to 7.1–8.5 months and with the total duration of treatment up to 18.6–21.5 months.
What Do These Findings Mean?
These findings suggest that the use of specific drugs, the use of a greater number of effective drugs, and longer treatments may be associated with treatment success and the survival of patients with MDR-TR. However, these findings need to be interpreted with caution because of limitations in this study that may have affected the accuracy of its findings. For example, the researchers did not include all the studies they found through the systematic reviews in their meta-analysis (some authors did not respond to requests for individual patient data, for example), which may have introduced bias. Moreover, because the patients included in the meta-analysis were treated at 32 centers, there were many differences in their management, some of which may have affected the accuracy of the findings. Because of these and other limitations, the researchers note that, although their findings highlight several important questions about the treatment of MDR-TB, randomized controlled trials are urgently needed to determine the optimal treatment for MDR-TB.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001300.
The World Health Organization provides information on all aspects of tuberculosis, including MDR-TB; its guidelines for the programmatic management of drug-resistant tuberculosis are available
The US Centers for Disease Control and Prevention has information about tuberculosis, including information on the treatment of tuberculosis and on MDR-TB
The US National Institute of Allergy and Infectious Diseases also has information on all aspects of tuberculosis, including a drug-resistant tuberculosis visual tour
MedlinePlus has links to further information about tuberculosis (in English and Spanish)
TB & ME, a collaborative blogging project run by patients being treated for multidrug-resistant tuberculosis and Medecins sans Frontieres, provides information about MDR-TB and patient stories about treatment for MDR-TB
The Tuberculosis Survival Project, which aims to raise awareness of tuberculosis and provide support for people with tuberculosis, also provides personal stories about treatment for tuberculosis
doi:10.1371/journal.pmed.1001300
PMCID: PMC3429397  PMID: 22952439
12.  Risk Factors Associated with Default from Multi- and Extensively Drug-Resistant Tuberculosis Treatment, Uzbekistan: A Retrospective Cohort Analysis 
PLoS ONE  2013;8(11):e78364.
Background
The Médecins Sans Frontières project of Uzbekistan has provided multidrug-resistant tuberculosis treatment in the Karakalpakstan region since 2003. Rates of default from treatment have been high, despite psychosocial support, increasing particularly since programme scale-up in 2007. We aimed to determine factors associated with default in multi- and extensively drug-resistant tuberculosis patients who started treatment between 2003 and 2008 and thus had finished approximately 2 years of treatment by the end of 2010.
Methods
A retrospective cohort analysis of multi- and extensively drug-resistant tuberculosis patients enrolled in treatment between 2003 and 2008 compared baseline demographic characteristics and possible risk factors for default. Default was defined as missing ≥60 consecutive days of treatment (all drugs). Data were routinely collected during treatment and entered in a database. Potential risk factors for default were assessed in univariate analysis using chi-square test and in multivariate analysis with logistic regression.
Results
20% (142/710) of patients defaulted after a median of 6 months treatment (IQR 2.6–9.9). Factors associated with default included severity of resistance patterns (pre-extensively drug-resistant/extensively drug-resistant tuberculosis adjusted odds ratio 0.52, 95%CI: 0.31–0.86), previous default (2.38, 1.09–5.24) and age >45 years (1.77, 1.10–2.87). The default rate was 14% (42/294) for patients enrolled 2003–2006 and 24% (100/416) for 2007–2008 enrolments (p = 0.001).
Conclusions
Default from treatment was high and increased with programme scale-up. It is essential to ensure scale-up of treatment is accompanied with scale-up of staff and patient support. A successful first course of tuberculosis treatment is important; patients who had previously defaulted were at increased risk of default and death. The protective effect of severe resistance profiles suggests that understanding disease severity or fear may motivate against default. Targeted health education and support for at-risk patients after 5 months of treatment when many begin to feel better may decrease default.
doi:10.1371/journal.pone.0078364
PMCID: PMC3819387  PMID: 24223148
13.  Alarming Levels of Drug-Resistant Tuberculosis in HIV-Infected Patients in Metropolitan Mumbai, India 
PLoS ONE  2014;9(10):e110461.
Background
Drug-resistant tuberculosis (DR-TB) is a looming threat to tuberculosis control in India. However, no countrywide prevalence data are available. The burden of DR-TB in HIV-co-infected patients is likewise unknown. Undiagnosed and untreated DR-TB among HIV-infected patients is a major cause of mortality and morbidity. We aimed to assess the prevalence of DR-TB (defined as resistance to any anti-TB drug) in patients attending public antiretroviral treatment (ART) centers in greater metropolitan Mumbai, India.
Methods
A cross-sectional survey was conducted among adults and children ART-center attendees. Smear microscopy, culture and drug-susceptibility-testing (DST) against all first and second-line TB-drugs using phenotypic liquid culture (MGIT) were conducted on all presumptive tuberculosis patients. Analyses were performed to determine DR-TB prevalence and resistance patterns separately for new and previously treated, culture-positive TB-cases.
Results
Between March 2013 and January 2014, ART-center attendees were screened during 14135 visits, of whom 1724 had presumptive TB. Of 1724 attendees, 72 (4%) were smear-positive and 202 (12%) had a positive culture for Mycobacterium tuberculosis. Overall DR-TB was diagnosed in 68 (34%, 95% CI: 27%–40%) TB-patients. The proportions of DR-TB were 25% (29/114) and 44% (39/88) among new and previously treated cases respectively. The patterns of DR-TB were: 21% mono-resistant, 12% poly-resistant, 38% multidrug-resistant (MDR-TB), 21% pre-extensively-drug-resistant (MDR-TB plus resistance to either a fluoroquinolone or second-line injectable), 6% extensively drug-resistant (XDR-TB) and 2% extremely drug-resistant TB (XDR-TB plus resistance to any group-IV/V drug). Only previous history of TB was significantly associated with the diagnosis of DR-TB in multivariate models.
Conclusion
The burden of DR-TB among HIV-infected patients attending public ART-centers in Mumbai was alarmingly high, likely representing ongoing transmission in the community and health facilities. These data highlight the need to promptly diagnose drug-resistance among all HIV-infected patients by systematically offering access to first and second-line DST to all patients with ‘presumptive TB’ rather than ‘presumptive DR-TB’ and tailor the treatment regimen based on the resistance patterns.
doi:10.1371/journal.pone.0110461
PMCID: PMC4204864  PMID: 25333696
14.  Molecular Epidemiology, Drug Susceptibility and Economic Aspects of Tuberculosis in Mubende District, Uganda 
PLoS ONE  2013;8(5):e64745.
Background
Tuberculosis (TB) remains a global public health problem whose effects have major impact in developing countries like Uganda. This study aimed at investigating genotypic characteristics and drug resistance profiles of Mycobacterium tuberculosis isolated from suspected TB patients. Furthermore, risk factors and economic burdens that could affect the current control strategies were studied.
Methods
TB suspected patients were examined in a cross-sectional study at the Mubende regional referral hospital between February and July 2011. A questionnaire was administered to each patient to obtain information associated with TB prevalence. Isolates of M. tuberculosis recovered during sampling were examined for drug resistance to first line anti-TB drugs using the BACTEC-MGIT960TMsystem. All isolates were further characterized using deletion analysis, spoligotyping and MIRU-VNTR analysis. Data were analyzed using different software; MIRU-VNTR plus, SITVITWEB, BioNumerics and multivariable regression models.
Results
M. tuberculosis was isolated from 74 out of 344 patients, 48 of these were co-infected with HIV. Results from the questionnaire showed that previously treated TB, co-infection with HIV, cigarette smoking, and overcrowding were risk factors associated with TB, while high medical related transport bills were identified as an economic burden. Out of the 67 isolates that gave interpretable results, 23 different spoligopatterns were detected, nine of which were novel patterns. T2 with the sub types Uganda-I and Uganda-II was the most predominant lineage detected. Antibiotic resistance was detected in 19% and multidrug resistance was detected in 3% of the isolates.
Conclusion
The study detected M. tuberculosis from 21% of examined TB patients, 62% of whom were also HIV positive. There is a heterogeneous pool of genotypes that circulate in this area, with the T2 lineage being the most predominant. High medical related transport bills and drug resistance could undermine the usefulness of the current TB strategic interventions.
doi:10.1371/journal.pone.0064745
PMCID: PMC3669366  PMID: 23741382
15.  Minority HIV-1 Drug Resistance Mutations Are Present in Antiretroviral Treatment–Naïve Populations and Associate with Reduced Treatment Efficacy 
PLoS Medicine  2008;5(7):e158.
Background
Transmitted HIV-1 drug resistance can compromise initial antiretroviral therapy (ART); therefore, its detection is important for patient management. The absence of drug-associated selection pressure in treatment-naïve persons can cause drug-resistant viruses to decline to levels undetectable by conventional bulk sequencing (minority drug-resistant variants). We used sensitive and simple tests to investigate evidence of transmitted drug resistance in antiretroviral drug-naïve persons and assess the clinical implications of minority drug-resistant variants.
Methods and Findings
We performed a cross-sectional analysis of transmitted HIV-1 drug resistance and a case-control study of the impact of minority drug resistance on treatment response. For the cross-sectional analysis, we examined viral RNA from newly diagnosed ART-naïve persons in the US and Canada who had no detectable (wild type, n = 205) or one or more resistance-related mutations (n = 303) by conventional sequencing. Eight validated real-time PCR-based assays were used to test for minority drug resistance mutations (protease L90M and reverse transcriptase M41L, K70R, K103N, Y181C, M184V, and T215F/Y) above naturally occurring frequencies. The sensitive real-time PCR testing identified one to three minority drug resistance mutation(s) in 34/205 (17%) newly diagnosed persons who had wild-type virus by conventional genotyping; four (2%) individuals had mutations associated with resistance to two drug classes. Among 30/303 (10%) samples with bulk genotype resistance mutations we found at least one minority variant with a different drug resistance mutation. For the case-control study, we assessed the impact of three treatment-relevant drug resistance mutations at baseline from a separate group of 316 previously ART-naïve persons with no evidence of drug resistance on bulk genotype testing who were placed on efavirenz-based regimens. We found that 7/95 (7%) persons who experienced virologic failure had minority drug resistance mutations at baseline; however, minority resistance was found in only 2/221 (0.9%) treatment successes (Fisher exact test, p = 0.0038).
Conclusions
These data suggest that a considerable proportion of transmitted HIV-1 drug resistance is undetected by conventional genotyping and that minority mutations can have clinical consequences. With no treatment history to help guide therapies for drug-naïve persons, the findings suggest an important role for sensitive baseline drug resistance testing.
Using real-time PCR to detect HIV resistance mutations present at low levels, Jeffrey Johnson and colleagues investigate prevalence and clinical implications of minority transmitted mutations.
Editors' Summary
Background
Since the mid-1990s, several powerful antiretroviral drug combinations have been developed that have greatly improved the prognosis of HIV infection. All antiretroviral therapy (ART) regimens combine drugs that act against HIV in different ways (so-called different drug classes). Multiple drugs are necessary because HIV continually accumulates random changes (mutations) in its genetic material (genome). Some of these mutations make HIV resistant to individual antiretroviral drugs, so a mixture of drugs is needed to keep the virus in check. However, the efficacy of ART (which itself selects for drug-resistant variants by giving them a growth advantage over drug-sensitive variants) is substantially reduced when these variants account for more than about 20% of the viruses in an infected person. This level of variant virus can be detected in blood samples with a technique called bulk sequencing. In North America and Europe, where ART has been widely used for many years, around 20% of HIV-infected people who have taken ART themselves develop this level of drug-resistant virus, which can be transmitted by the same routes as nonresistant HIV (typically unprotected sexual intercourse or needle sharing). In such cases, the person acquiring drug-resistant HIV may experience treatment failure when drugs later fail to work against the resistant virus. In these countries, therefore, resistance testing by bulk sequencing is done routinely before ART is initiated to decide which antiviral drugs are likely to be effective.
Why Was This Study Done?
Several years usually elapse between the time a person becomes infected with HIV and the time he or she starts ART. During this time, the absence of selection pressure from antiviral drugs means that transmitted drug-resistant variants tend to decline to levels undetectable by bulk sequencing. These “minority drug-resistant variants” can be detected using other more sensitive tests but it is not known what proportion of HIV-infected people who have never taken ART carry minority drug-resistant variants (the “prevalence” of these variants). It is also unknown whether the presence of minority drug-resistant variants reduces the success of ART. In this paper, the researchers first report a “cross-sectional” study in North America using a sensitive assay to determine the prevalence of minority drug-resistant viruses among HIV-infected people who had never received ART. They then investigate whether minority drug-resistant variants have any impact on the effectiveness of ART in a “case-control” study.
What Did the Researchers Do and Find?
In their cross-sectional study, the researchers used a highly sensitive test for detecting mutations (called a real-time PCR-based assay) to look for low levels of viruses carrying any of eight major drug-resistance mutations in people with newly diagnosed HIV infection who reported no prior treatment with ART. Seventeen percent of the people who had only wild-type (nonmutated) virus by bulk sequencing (205 participants) were found, in fact, to carry low levels of virus variants with 1–3 drug-resistance mutations; 2% of them carried viruses resistant to two different drug classes (called multi-drug resistance). Among the people with resistance mutations detected by bulk sequencing (303 participants), 10% had at least one additional minority drug-resistant variant, often a viral variant that was resistant to a drug class different from that detected by bulk sequencing. In the case-control study, the researchers used their sensitive assays to measure the levels of viruses containing any of the three most common drug resistance mutations likely to affect viral responses to the antiretroviral drugs efavirenz and lamivudine in 316 people just before they started their first HIV treatment, which included these drugs. Of people for whom ART failed, 7% were infected with minority drug-resistant virus variants at baseline compared with only 0.9% of people for whom ART worked; this difference was statistically significant.
What Do These Findings Mean?
The findings of the cross-sectional study indicate that conventional bulk sequencing fails to detect a large proportion of transmitted HIV drug resistance and suggest that the transmission of drug-resistant variants from infectious ART-experienced people to ART-naïve individuals might not be uncommon. The findings of the case-control study suggest that the minority drug-resistant HIV variants may have clinical consequences. That is, the presence of such variants in individuals who have not previously taken ART may reduce the efficacy of some ART regimens. However, the number of participants meeting the criteria for analysis in the cross-sectional study was limited, and the association between minority resistance and treatment failure may have been influenced by other factors. Taken together, these findings suggest that, to ensure that first-line ART is as effective as possible, greater efforts should be made to prevent HIV transmission, whether from ART-experienced or ART-naive people. However, because data on minority drug-resistant virus are limited, more studies— particularly with recent populations—are needed before testing for these variants can be considered appropriate in the clinical management of newly diagnosed HIV infection.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050158.
This study is further discussed in a PLoS Medicine Perspective by Steven G. Deeks
Information is available from the US National Institute of Allergy and Infectious Diseases on HIV infection and AIDS
HIV InSite has comprehensive information on all aspects of HIV/AIDS, including links to fact sheets (in English, French, and Spanish) about antiretrovirals and information on genetic testing for HIV drug resistance
NAM, a UK registered charity, provides information about all aspects of HIVand AIDS, including fact sheets on types of HIV drug, drug resistance, and resistance tests (in English, Spanish, French, Portuguese, and Russian)
The US Centers for Disease Control and Prevention provides information on HIV/AIDS and on treatment (in English and Spanish)
doi:10.1371/journal.pmed.0050158
PMCID: PMC2488194  PMID: 18666824
16.  Rates of drug resistance and risk factor analysis in civilian and prison patients with tuberculosis in Samara Region, Russia 
Thorax  2005;60(2):130-135.
Background: Tuberculosis (TB) and HIV rates continue to escalate in Russia, but true rates for drug resistance, especially multidrug resistant tuberculosis (MDR TB), are unknown. A study was conducted with the aims of identifying first line drug resistance, both in the civilian and prison sectors, for new and previously treated cases; and risk factors for the development of drug resistance.
Methods: A cross sectional survey was undertaken of 600 patients (309 civilians, 291 prisoners) with bacteriologically confirmed pulmonary TB over a 1 year period during 2001–2 in Samara Oblast, Russia.
Results: The prevalence of isoniazid, rifampicin, streptomycin, ethambutol and pyrazinamide resistance in new TB cases (civilian and prison patients) was 38.0%, 25.2%, 34.6%, 14.7%, and 7.2%, respectively. The prevalence of MDR TB was 22.7%, 19.8%, and 37.3% in all new cases, new civilian cases, and new prison cases, respectively, with an overall prevalence of 45.5% and 55.3% in previously treated cases. Factors associated with resistance included previous TB treatment for more than 4 weeks, smoking (for isoniazid resistance), the presence of cavitations on the chest radiograph, and imprisonment. HIV was not associated with resistance in all patients. The rates of resistance were significantly higher in prisoners, with rate ratios (RR) of 1.9 (95% CI 1.1 to 3.2) for MDR TB, 1.9 (95% CI 1.1 to 3.2) for rifampicin, and 1.6 (95% CI 1.0 to 2.6) for isoniazid.
Conclusions: Rates of first line drug resistance are high, particularly in prisoners and previously treated cases. TB control programmes should initially focus on standardised treatment to maximise cure, combined with measures to reduce institutional TB spread (particularly in prisons) coupled with early diagnosis of MDR TB to reduce the spread and development of resistance.
doi:10.1136/thx.2004.026922
PMCID: PMC1747303  PMID: 15681501
17.  Primary Drug-Resistant Tuberculosis in Hanoi, Viet Nam: Present Status and Risk Factors 
PLoS ONE  2013;8(8):e71867.
Introduction
Resistance of Mycobacterium tuberculosis (MTB) to anti-tuberculosis (TB) drugs presents a serious challenge to TB control worldwide. We investigated the status of drug resistance, including multidrug-resistant (MDR) TB, and possible risk factors among newly diagnosed TB patients in Hanoi, the capital of Viet Nam.
Methods
Clinical and epidemiological information was collected from 506 newly diagnosed patients with sputum smear- and culture-positive TB, and 489 (96.6%) MTB isolates were subjected to conventional drug susceptibility testing, spoligotyping, and 15-locus variable numbers of tandem repeats typing. Adjusted odds ratios (aORs) were calculated to analyze the risk factors for primary drug resistance.
Results
Of 489 isolates, 298 (60.9%) were sensitive to all drugs tested. Resistance to isoniazid, rifampicin, streptomycin, ethambutol, and MDR accounted for 28.2%, 4.9%, 28.2%, 2.9%, and 4.5%, respectively. Of 24 isolates with rifampicin resistance, 22 (91.7%) were MDR and also resistant to streptomycin, except one case. Factors associated with isoniazid resistance included living in old urban areas, presence of the Beijing genotype, and clustered strains [aOR = 2.23, 95% confidence interval (CI) 1.15–4.35; 1.91, 1.18–3.10; and 1.69, 1.06–2.69, respectively). The Beijing genotype was also associated with streptomycin resistance (aOR = 2.10, 95% CI 1.29–3.40). Human immunodeficiency virus (HIV) coinfection was associated with rifampicin resistance and MDR (aOR = 5.42, 95% CI 2.07–14.14; 6.23, 2.34–16.58, respectively).
Conclusion
Isoniazid and streptomycin resistance was observed in more than a quarter of TB patients without treatment history in Hanoi. Transmission of isoniazid-resistant TB among younger people should be carefully monitored in urban areas, where Beijing strains and HIV coinfection are prevalent. Choosing an optimal treatment regimen on the basis of the results of drug susceptibility tests and monitoring of treatment adherence would minimize further development of drug resistance strains.
doi:10.1371/journal.pone.0071867
PMCID: PMC3742467  PMID: 23967255
18.  Multidrug-resistant Pulmonary Tuberculosis Among Young Korean Soldiers in a Communal Setting 
Journal of Korean Medical Science  2009;24(4):592-595.
The goal of this study was to evaluate the prevalence of first-line anti-tuberculosis drug resistance and risk factors associated with multidrug-resistant tuberculosis (MDR TB) among young soldiers in the Korean military, which has a strict tuberculosis control program. All patients with culture-confirmed pulmonary tuberculosis during their service at the Armed Forces Capital Hospital from January 2001 to December 2006 were enrolled in the study. Drug resistant Mycobacterium tuberculosis was isolated from 18 patients (12.2%) and multidrug-resistant M. tuberculosis was isolated from 12 patients (8.1%). Previous treatment of tuberculosis and the presence of a cavity on the patient's chest computed tomography scan were associated with MDR TB; military rank, smoking habits, and positive acid-fast bacilli smears were not associated with MDR TB. In a multiple logistic regression analysis, previous treatment of tuberculosis was a significant independent risk factor for MDR TB (odds ratio 6.12, 95% confidence interval 1.53-24.46). The prevalence of drug resistant tuberculosis among young soldiers in the Korean military was moderately high and the majority of resistant cases were found in patients who had undergone previous treatment of tuberculosis. Based on our results, we suggest that relapsed tuberculosis cases within communal settings should be cautiously managed until the drug susceptibility tests report is completed, even if previous treatment results were satisfactory.
doi:10.3346/jkms.2009.24.4.592
PMCID: PMC2719201  PMID: 19654938
Tuberculosis, Pulmonary; Tuberculosis, Multidrug-Resistant; Korea; Military Personnel
19.  Tuberculosis Recurrence and Mortality after Successful Treatment: Impact of Drug Resistance 
PLoS Medicine  2006;3(10):e384.
Background
The DOTS (directly observed treatment short-course) strategy for tuberculosis (TB) control is recommended by the World Health Organization globally. However, there are few studies of long-term TB treatment outcomes from DOTS programs in high-burden settings and particularly settings of high drug resistance. A DOTS program was implemented progressively in Karakalpakstan, Uzbekistan starting in 1998. The total case notification rate in 2003 was 462/100,000, and a drug resistance survey found multidrug-resistant (MDR) Mycobacterium tuberculosis strains among 13% of new and 40% of previously treated patients. A retrospective, observational study was conducted to assess the capacity of standardized short-course chemotherapy to effectively cure patients with TB in this setting.
Methods and Findings
Using routine data sources, 213 patients who were sputum smear-positive for TB, included in the drug resistance survey and diagnosed consecutively in 2001–2002 from four districts, were followed up to a median of 22 months from diagnosis, to determine mortality and subsequent TB rediagnosis. Valid follow-up data were obtained for 197 (92%) of these patients. Mortality was high, with an average of 15% (95% confidence interval, 11% to 19%) dying per year after diagnosis (6% of 73 pansusceptible cases and 43% of 55 MDR TB cases also died per year). While 73 (74%) of the 99 new cases were “successfully” treated, 25 (34%) of these patients were subsequently rediagnosed with recurrent TB (13 were smear-positive on rediagnosis). Recurrence ranged from ten (23%) of 43 new, pansusceptible cases to six (60%) of ten previously treated MDR TB cases. MDR M. tuberculosis infection and previous TB treatment predicted unsuccessful DOTS treatment, while initial drug resistance contributed substantially to both mortality and disease recurrence after successful DOTS treatment.
Conclusions
These results suggest that specific treatment of drug-resistant TB is needed in similar settings of high drug resistance. High disease recurrence after successful treatment, even for drug-susceptible cases, suggests that at least in this setting, end-of-treatment outcomes may not reflect the longer-term status of patients, with consequent negative impacts for patients and for TB control.
A retrospective, observational study was conducted to assess the effectiveness of a "DOTS" tuberculosis control program in Uzbekistan. High rates of disease recurrence were found among patients whose treatment had been initially successful.
Editors' Summary
Background.
Throughout history, tuberculosis (TB) has been a leading infectious cause of death—it kills about 2 million people every year. Until the 1940s, there was no effective treatment for TB, a chronic bacterial infection, usually of the lungs. Then, antibiotics active against the bacteria that cause TB—Mycobacterium tuberculosis—were introduced, and its incidence (the annual number of new cases) declined rapidly, particularly in developed countries. However, in the 1980s, there was a resurgence of TB, much of it driven by the HIV/AIDS epidemic—people with damaged immune systems are very susceptible to TB—and the emergence of drug-resistant M. tuberculosis. In 1995, the World Health Organization instigated what it called “DOTS,” an international strategy for global TB control. Central to DOTS is directly observed standardized short-course drug treatment. To prevent relapse and the emergence of drug-resistant bacteria, TB patients have to take antibiotics regularly for six months, even if they feel better sooner. The DOTS approach ensures that they do this by having trained observers watch them swallow their medications.
Why Was This Study Done?
DOTS aims to detect 70% of new cases of sputum smear-positive TB (sputum is mucus coughed up from the lungs) and to treat 85% of these patients successfully. Both a cure—a negative smear at the end of treatment—and completion of treatment are recorded as “treatment successes.” There is no requirement in DOTS to check for TB recurrence, and few studies have investigated the long-term outcomes of treatment, particularly in areas with a high TB burden or where there is a problem with multidrug-resistant TB. Such data are needed to indicate whether DOTS can deliver global TB control. In this study, the researchers asked how often TB recurred in patients treated in a DOTS program in Karakalpakstan, Uzbekistan, an area with one of the highest incidences of multidrug-resistant TB.
What Did the Researchers Do and Find?
The researchers identified about 200 sputum smear-positive TB patients who were treated consecutively in the Karakalpakstan DOTS program in 2001–2002. For most of the patients, follow-up data were available for an average of 22 months, a legacy of the pre-DOTS TB treatment system in Uzbekistan. The researchers found that, although three-quarters of new cases were “successfully” treated (i.e., close to the DOTS goal), a third of these “successes” were later re-diagnosed with TB. Recurrence of TB was particularly common among patients whose initial disease was multidrug resistant. Previous TB treatment was also associated with an increased risk of disease recurrence. Overall, nearly a quarter of the study patients died from TB during the follow-up period. Again, patients initially infected with multidrug-resistant TB fared particularly badly. Finally, only 65% of successfully treated patients were still alive and had not been re-diagnosed with TB 18 months after completion of their treatment.
What Do These Findings Mean?
These high rates of disease recurrence and mortality suggest that DOTS might not be sufficient to control TB in areas like Karakalpakstan where the disease burden is high and multidrug-resistant infections are common. These poor long-term outcomes, note the researchers, are not hinted at by the end-of-treatment outcomes reported by the DOTS program. Limitations in the present study mean, however, that further studies are needed before these findings can be extrapolated to other settings. For example, the study used historical data so the researchers could not determine whether inadequate adherence to the DOTS program had contributed to the poor long-term outcome or whether disease recurrence was due to a relapse of the initial infection (which might indicate poor treatment adherence) or a new infection. Nevertheless, the current results warn against relying on end-of-treatment outcomes to judge the potential effectiveness of DOTS in controlling TB, and suggest that the expansion of DOTS-Plus, a supplement to DOTS for use where multidrug resistant TB is common, should be made a priority.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0030384.
US National Institute of Allergy and Infectious Diseases, patient fact sheet on tuberculosis
US Centers for Disease Control and Prevention, information for patients and professionals on tuberculosis
MedlinePlusencyclopedia entry on tuberculosis
NHS Direct Online, patient information on tuberculosis from the UK National Health Service
World Health Organization information on the global elimination of tuberculosis, including details of DOTS and DOTS-Plus
Medécin sans Frontières; information on TB and other health issues in Karakalpakstan
doi:10.1371/journal.pmed.0030384
PMCID: PMC1584414  PMID: 17020405
20.  Mycobacterium tuberculosis spoligotypes and drug susceptibility pattern of isolates from tuberculosis patients in South-Western Uganda 
Background
Determination of the prevalence and drug susceptibility of the M. tuberculosis strains is important in tuberculosis control. We determined the genetic diversity and susceptibility profiles of mycobacteria isolated from tuberculosis patients in Mbarara, South Western Uganda.
Methods
We enrolled, consecutively; all newly diagnosed and previously treated smear-positive TB patients aged ≥ 18 years. The isolates were characterized using regions of difference (RD) analysis and spoligotyping. Drug resistance against rifampicin and isoniazid were tested using the Genotype® MDRTBplus assay and the indirect proportion method on Lowenstein-Jensen media. HIV-1 testing was performed using two rapid HIV tests.
Results
A total of 125 isolates from 167 TB suspects (60% males) with a mean age 33.7 years and HIV prevalence of 67.9% (55/81) were analyzed. Majority (92.8%) were new cases while only 7.2% were retreatment cases. All the 125 isolates were identified as M. tuberculosis strict sense with the majority (92.8%) of the isolates being modern strains while seven (7.2%) isolates were ancestral strains. Spoligotyping revealed 79 spoligotype patterns, with an overall diversity of 63.2%. Sixty two (49.6%) of the isolates formed 16 clusters consisting of 2-15 isolates each. A majority (59.2%) of the isolates belong to the Uganda genotype group of strains. The major shared spoligotypes in our sample were SIT 135 (T2-Uganda) with 15 isolates and SIT 128 (T2) with 3 isolates. Sixty nine (87%) of the 79 patterns had not yet been defined in the SpolDB4.0.database. Resistance mutations to either RIF or INH were detected in 6.4% of the isolates. Multidrug resistance, INH and RIF resistance was 1.6%, 3.2% and 4.8%, respectively. The rpoβ gene mutations seen in the sample were D516V, S531L, H526Y H526D and D516V, while one strain had a Δ1 mutation in the wild type probes. There were three strains with katG (codon 315) gene mutations only while one strain showed the inhA promoter gene mutation.
Conclusion
The present study shows that the TB epidemic in Mbarara is caused by modern M. tuberculosis strains mainly belonging to the Uganda genotype and anti-TB drug resistance rate in the region is low.
doi:10.1186/1471-2334-11-81
PMCID: PMC3100262  PMID: 21453482
21.  Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis in Multi-Ethnic Region, Xinjiang Uygur Autonomous Region, China 
PLoS ONE  2012;7(2):e32103.
Background
The multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) has emerged as a global threat. Xinjiang is a multi-ethnic region and suffered second highest incidence of TB in China. However, epidemiological information on MDR and XDR TB is scarcely investigated.
Methodology/Principal Findings
A prospective study was conducted to analyze the prevalence of MDR and XDR TB and the differences of drug resistance TB between Chinese Han and other nationalities population at Chest Hospital of Xinjiang Uygur Autonomous Region, China. We performed in vitro drug susceptibility testing of Mycobacterium tuberculosis to first- and second-line anti-tuberculosis drugs for all 1893 culture confirmed positive TB cases that were diagnosed between June 2009 and June 2011. Totally 1117 (59.0%, 95% CI, 56.8%–61.2%) clinical isolates were resistant to ≥1 first-line drugs; the prevalence of MDR TB was 13.2% (95% CI, 11.7%–14.7%), of which, 77 (30.8%; 95% CI, 25.0%–36.6%) and 31 (12.8%; 95% CI, 8.6%–17.0%) isolates were pre-XDR and XDR TB respectively. Among the MDR/XDR TB, Chinese Han patients were significantly less likely to be younger with an odds ratio 0.42 for age 20–29 years and 0.52 for age 40–49 years; Ptrend = 0.004), and Chinese Han patients has a lower prevalence of XDR TB (9.6%) than all the other nationality (14.9%).
Conclusions/Significance
The burden of drug resistance TB cases is sizeable, which highlights an urgent need to reinforce the control, detection and treatment strategies for drug resistance TB. However, the difference of MDR and XDR TB between Chinese Han and other nationalities was not observed.
doi:10.1371/journal.pone.0032103
PMCID: PMC3285197  PMID: 22384153
22.  Elucidating Emergence and Transmission of Multidrug-Resistant Tuberculosis in Treatment Experienced Patients by Whole Genome Sequencing 
PLoS ONE  2013;8(12):e83012.
Background
Understanding the emergence and spread of multidrug-resistant tuberculosis (MDR-TB) is crucial for its control. MDR-TB in previously treated patients is generally attributed to the selection of drug resistant mutants during inadequate therapy rather than transmission of a resistant strain. Traditional genotyping methods are not sufficient to distinguish strains in populations with a high burden of tuberculosis and it has previously been difficult to assess the degree of transmission in these settings. We have used whole genome analysis to investigate M. tuberculosis strains isolated from treatment experienced patients with MDR-TB in Uganda over a period of four years.
Methods and Findings
We used high throughput genome sequencing technology to investigate small polymorphisms and large deletions in 51 Mycobacterium tuberculosis samples from 41 treatment-experienced TB patients attending a TB referral and treatment clinic in Kampala. This was a convenience sample representing 69% of MDR-TB cases identified over the four year period. Low polymorphism was observed in longitudinal samples from individual patients (2-15 SNPs). Clusters of samples with less than 50 SNPs variation were examined. Three clusters comprising a total of 8 patients were found with almost identical genetic profiles, including mutations predictive for resistance to rifampicin and isoniazid, suggesting transmission of MDR-TB. Two patients with previous drug susceptible disease were found to have acquired MDR strains, one of which shared its genotype with an isolate from another patient in the cohort.
Conclusions
Whole genome sequence analysis identified MDR-TB strains that were shared by more than one patient. The transmission of multidrug-resistant disease in this cohort of retreatment patients emphasises the importance of early detection and need for infection control. Consideration should be given to rapid testing for drug resistance in patients undergoing treatment to monitor the emergence of resistance and permit early intervention to avoid onward transmission.
doi:10.1371/journal.pone.0083012
PMCID: PMC3859632  PMID: 24349420
23.  Experiences in anti-tuberculosis treatment in patients with multiple previous treatments and its impact on drug resistant tuberculosis epidemics 
Global Health Action  2014;7:10.3402/gha.v7.24593.
Background
Tuberculosis (TB) patients with a history of multiple anti-TB treatments are the ‘neglected’ group to the free anti-TB treatment policy in China.
Objective
To understand the experiences of TB patients with multiple previous treatments with regard to bacteriological diagnosis and treatment regimens, especially for second-line anti-TB drugs, and how this might influence the risks of multidrug and extensively drug-resistant TB (M/XDR-TB).
Design
A cross-sectional study was conducted in 10 county/district TB clinics in five provinces of China. The study participants were TB patients that had at least two previous treatment episodes that lasted longer than 1 month each. Face-to-face interviews and drug susceptibility testing (DST) were conducted with the consenting participants.
Results
A total of 328 TB patients were recruited. The proportion of multidrug-resistant tuberculosis (MDR-TB) was 58.2% in the 287 DST-confirmed patients. Forty-two percent of the patients did not complete their first treatment course. About 23.8% of the participants had a history of taking second-line drugs, and more than 77.8% of them were treated in county TB dispensaries where only sputum microscopy was applied. Multivariate analysis found that the use of second-line drugs was significantly associated with frequency of previous treatments (p<0.01), but not with drug resistance profiles of patients.
Conclusions
Patients with multiple previous treatments are at extremely high risk of MDR-TB in China. The unregulated use of second-line drugs bring about the threat of XDR-TB epidemic. DST-guided treatment and strict regulations of anti-TB treatment should be assured for the high-risk TB patients for the prevention and control of M/XDR-TB.
doi:10.3402/gha.v7.24593
PMCID: PMC4138495  PMID: 25138531
tuberculosis; drug resistance; second-line anti-tuberculosis drugs; treatment history; China
24.  Feasibility and Cost-Effectiveness of Treating Multidrug-Resistant Tuberculosis: A Cohort Study in the Philippines 
PLoS Medicine  2006;3(9):e352.
Background
Multidrug-resistant tuberculosis (MDR-TB) is an important global health problem, and a control strategy known as DOTS-Plus has existed since 1999. However, evidence regarding the feasibility, effectiveness, cost, and cost-effectiveness of DOTS-Plus is still limited.
Methodology/Principal Findings
We evaluated the feasibility, effectiveness, cost, and cost-effectiveness of a DOTS-Plus pilot project established at Makati Medical Center in Manila, the Philippines, in 1999. Patients with MDR-TB are treated with regimens, including first- and second-line drugs, tailored to their drug susceptibility pattern (i.e., individualised treatment). We considered the cohort enrolled between April 1999 and March 2002. During this three-year period, 118 patients were enrolled in the project; 117 were considered in the analysis. Seventy-one patients (61%) were cured, 12 (10%) failed treatment, 18 (15%) died, and 16 (14%) defaulted. The average cost per patient treated was US$3,355 from the perspective of the health system, of which US$1,557 was for drugs, and US$837 from the perspective of patients. The mean cost per disability-adjusted life year (DALY) gained by the DOTS-Plus project was US$242 (range US$85 to US$426).
Conclusions
Treatment of patients with MDR-TB using the DOTS-Plus strategy and individualised drug regimens can be feasible, comparatively effective, and cost-effective in low- and middle-income countries.
Evaluation of 117 patients enrolled in a DOTS-Plus pilot project in the Philippines showed that in this setting the strategy is feasible.
Editors' Summary
Background.
Tuberculosis (TB) causes the death of some 2 million people each year. An estimated one in three people worldwide are infected with Mycobacterium tuberculosis, the bacterium that causes the disease. Because single-drug treatment leads to treatment failure and antibiotic resistance, treatment for active TB is complicated, usually involving four different antibiotics, at least two of which are continued for six months or more. The World Health Organization (WHO) recommends a specific strategy (DOTS) for diagnosing and treating TB (see Web link below).
The DOTS approach includes standard regimens of first-line drugs which cure about 90% of patients with drug-susceptible TB, and which cost as little as US$10 per patient. Unfortunately, TB resistance to at least two of the most effective DOTS drugs has developed at sites in both industrialized and developing countries, causing approximately 460,000 cases of multidrug-resistant TB (MDR-TB) per year. Second-line antibiotics, which tend to be more expensive or more difficult to take, can effectively treat many cases of MDR-TB. “DOTS-Plus” programmes, which use combinations of first- and second-line drugs to treat MDR-TB, are therefore becoming increasingly important in controlling TB worldwide. A recent study found DOTS-Plus strategies to be cost-effective in Peru, but cure rates of MDR-TB were relatively low.
Why Was This Study Done?
Because the use of second-line antibiotics is costly and the treatment of MDR-TB has a higher failure rate than that of fully drug-susceptible TB, policymakers responsible for allocation of limited healthcare resources need information on how well DOTS-Plus programmes work and how much they cost to operate. This study was undertaken to assess the feasibility, effectiveness, and cost-effectiveness of a DOTS-Plus project in the Philippines, a lower middle–income country with a high rate of TB and approximately 25,000 cases of MDR-TB.
What Did the Researchers Do and Find? 
The researchers reported on a DOTS-Plus pilot project at Makati Medical Center in Manila, analyzing information from 118 patients enrolled in the project between 1999 and 2002. The diagnosis of MDR-TB was based on laboratory culture and antibiotic resistance testing of specimens from patients who had continued symptoms of TB following DOTS treatment, or other evidence of possible MDR-TB. Patients were treated with five-drug combinations individually selected based on resistance testing results, and administered under direct observation. After cultures had remained consistently negative for six months, patients were switched to a four-drug regimen with intermittent clinic observation until cultures remained negative for at least 18 months.
Cost-effectiveness was assessed by comparing the costs and effects of the project to the costs and effects that would have applied in the absence of the project, namely, no treatment of MDR-TB (except what patients could have purchased privately), or standard first-line DOTS treatment (which would not cure the majority of patients with MDR-TB, and is associated with a high chance of relapse in those who do appear cured). Costs of the DOTS-Plus project were based on expenditure records, project records, and interviews with staff, patients, and funding agencies. Effects of the project were based on treatment outcomes observed among enrolled patients, as well as on data on long-term outcomes among patients treated for MDR-TB in the US who were followed for up to ten years. Treatment costs for the situation in which no DOTS-Plus project exists were estimated using national data reported to WHO, as well as questionnaires administered to local patients in whom DOTS treatment had failed. Treatment outcomes where DOTS-Plus is not available were estimated from studies done in other TB-affected countries.
The researchers found that the cure rate of MDR-TB in this project was 61%. The cost per patient treated was US$4,192. They also calculated that the cost-effectiveness of the DOTS-Plus strategy was US$242 per disability-adjusted life year (DALY) gained, of which US$179 was paid by the healthcare system.
What Do These Findings Mean?
The cure rate for MDR-TB in this project compares favourably to rates in other resource-limited settings where second-line TB drugs are used, and is much higher than in areas where these drugs are not available. From the standpoint of efficacy and patient well-being, then, this study supports the necessity of DOTS-Plus treatment. In purely economic terms, the cost of US$200–US$250 per DALY gained is cost-effective in comparison with other healthcare interventions. Specifically, because the gross national income per person in the Philippines is US$1,080, someone who can return to work following MDR-TB treatment costing US$250 per year gained of working life will provide work that is worth four times more, on average, than the cost of the treatment.
Although this study provides encouraging confirmation that DOTS-Plus programmes can be effective and cost-effective in a resource-limited setting, these findings are subject to several limitations. First, the data used to estimate treatment outcomes and the costs associated with chronic MDR-TB when DOTS-Plus treatment is not available were limited. Also, the pilot project in this study included only 118 of 171 eligible patients, leaving open the possibility that the other 53 patients might have had different outcomes. In addition, the long-term relapse rate in the treated patients is unknown. Finally, the conclusion that one model programme is effective does not mean that other programmes will do well under less favourable circumstances. Nonetheless, as MDR-TB continues to spread in the developing world, a good example is good news. A Perspective by Paul Garner and colleagues in this issue of PLoS Medicine (DOI: 10.1371/journal.pmed.0030350) discusses the study further.
Additional Information. 
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0030352.
Basic information about tuberculosis can be found on the Web site of the US National Institute of Allergy and Infectious Diseases (NIAID)
The Web site of the World Health Organization's Stop TB department outlines both the DOTS and DOTS-Plus strategies
TB Alert, a UK-based charity that promotes TB awareness worldwide, has information on TB in several European, African, and Asian languages
doi:10.1371/journal.pmed.0030352
PMCID: PMC1564168  PMID: 16968123
25.  Multidrug-Resistant Tuberculosis Treatment Outcomes in Karakalpakstan, Uzbekistan: Treatment Complexity and XDR-TB among Treatment Failures 
PLoS ONE  2007;2(11):e1126.
Background
A pilot programme to treat multidrug-resistant TB (MDR-TB) was implemented in Karakalpakstan, Uzbekistan in 2003. This region has particularly high levels of MDR-TB, with 13% and 40% among new and previously treated cases, respectively.
Methodology
This study describes the treatment process and outcomes for the first cohort of patients enrolled in the programme, between October 2003 and January 2005. Confirmed MDR-TB cases were treated with an individualised, second-line drug regimen based on drug susceptibility test results, while suspected MDR-TB cases were treated with a standardised regimen pending susceptibility results.
Principal Findings
Of 108 MDR-TB patients, 87 were started on treatment during the study period. Of these, 33 (38%) were infected with strains resistant to at least one second-line drug at baseline, but none had initial ofloxacin resistance. Treatment was successful for 54 (62%) patients, with 13 (15%) dying during treatment, 12 (14%) defaulting and 8 (8%) failing treatment. Poor clinical condition and baseline second-line resistance contributed to treatment failure or death. Treatment regimens were changed in 71 (82%) patients due to severe adverse events or drug resistance. Adverse events were most commonly attributed to cycloserine, ethionamide and p-aminosalicylic acid. Extensively drug resistant TB (XDR-TB) was found among 4 of the 6 patients who failed treatment and were still alive in November 2006.
Conclusions
While acceptable treatment success was achieved, the complexity of treatment and the development of XDR-TB among treatment failures are important issues to be addressed when considering scaling up MDR-TB treatment.
doi:10.1371/journal.pone.0001126
PMCID: PMC2040509  PMID: 17987113

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