Search tips
Search criteria

Results 1-25 (98)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
more »
1.  Evaluation of Polysaccharide-Based Latex Agglutination Assays for the Rapid Detection of Antibodies to Burkholderia pseudomallei 
Melioidosis is a severe disease caused by the Gram-negative bacterium Burkholderia pseudomallei. Diagnosis of melioidosis currently relies on the isolation of B. pseudomallei from clinical samples, which can take several days. An indirect hemagglutination assay (IHA) is widely used for serodiagnosis, but it has a short shelf life, is poorly standardized, and requires a viable bacteria culture performed in a biosafety level 3 (BSL-3) laboratory. To improve the diagnostic methods, we have developed two rapid latex agglutination tests based on purified B. pseudomallei O-polysaccharide (OPS) and capsular polysaccharide (CPS) antigens. The immunodiagnostic potential of these tests was evaluated using serum from culture-confirmed melioidosis patients (N = 143) and healthy donors from either endemic (N = 199) or non-endemic areas (N = 90). The sensitivity of the OPS-based latex agglutination assay (OPS-latex; 84.4%) was significantly higher than both the CPS-latex (69.5%) (P < 0.001) and IHA (69.5%) (P = 0.001). When evaluated with Thai donor serum, the OPS-latex had comparable specificity (56.9%) to the CPS-latex (63.8%) (P = 0.053), but was significantly lower than the IHA (67.6%) (P = 0.002). In contrast, all tests with U.S. donor serum were highly specific (≥ 97.8%). These results suggest that polysaccharide-based latex agglutination assays may be useful for serodiagnosis of melioidosis in non-endemic areas.
PMCID: PMC4559694  PMID: 26123956
2.  Antimicrobial Disk Susceptibility Testing of Leptospira spp. Using Leptospira Vanaporn Wuthiekanun (LVW) Agar 
Leptospira Vanaporn Wuthiekanun (LVW) agar was used to develop a disk diffusion assay for Leptospira spp. Ten pathogenic Leptospira isolates were tested, all of which were susceptible to 17 antimicrobial agents (amoxicillin/clavulanic acid, amoxicillin, azithromycin, cefoxitin, ceftazidime, ceftriaxone, chloramphenicol, ciprofloxacin, clindamycin, doripenem, doxycycline, gentamicin, linezolid, nitrofurantoin, penicillin, piperacillin/tazobactam, and tetracycline). All 10 isolates had no zone of growth inhibition for four antimicrobials (fosfomycin, nalidixic acid, rifampicin, and trimethoprim/sulfamethoxazole). Of the ten Leptospira, seven had a growth inhibition zone of ≤ 21 mm for aztreonam, the zone diameter susceptibility break point for Enterobacteriaceae. This assay could find utility as a simple screening method during the epidemiological surveillance of antimicrobial resistance in Leptospira spp.
PMCID: PMC4530741  PMID: 26055750
3.  Consensus on the Development of Vaccines against Naturally Acquired Melioidosis 
Emerging Infectious Diseases  2015;21(6):e141480.
Several candidates for a vaccine against Burkholderia pseudomallei, the causal bacterium of melioidosis, have been developed, and a rational approach is now needed to select and advance candidates for testing in relevant nonhuman primate models and in human clinical trials. Development of such a vaccine was the topic of a meeting in the United Kingdom in March 2014 attended by international candidate vaccine developers, researchers, and government health officials. The focus of the meeting was advancement of vaccines for prevention of natural infection, rather than for protection from the organism’s known potential for use as a biological weapon. A direct comparison of candidate vaccines in well-characterized mouse models was proposed. Knowledge gaps requiring further research were identified. Recommendations were made to accelerate the development of an effective vaccine against melioidosis.
PMCID: PMC4451926  PMID: 25992835
Burkholderia pseudomallei; melioidosis; Whitmore’s disease; bacteria; vaccine; antimicrobial drugs; prevention; Steering Group on Melioidosis Vaccine Development; intraperitoneal; intravenous; aerosol inhalation; intranasal; challenge dose
4.  How to Determine the Accuracy of an Alternative Diagnostic Test when It Is Actually Better than the Reference Tests: A Re-Evaluation of Diagnostic Tests for Scrub Typhus Using Bayesian LCMs 
PLoS ONE  2015;10(5):e0114930.
The indirect immunofluorescence assay (IFA) is considered a reference test for scrub typhus. Recently, the Scrub Typhus Infection Criteria (STIC; a combination of culture, PCR assays and IFA IgM) were proposed as a reference standard for evaluating alternative diagnostic tests. Here, we use Bayesian latent class models (LCMs) to estimate the true accuracy of each diagnostic test, and of STIC, for diagnosing scrub typhus.
Methods/Principal Findings
Data from 161 patients with undifferentiated fever were re-evaluated using Bayesian LCMs. Every patient was evaluated for the presence of an eschar, and tested with blood culture for Orientia tsutsugamushi, three different PCR assays, IFA IgM, and the Panbio IgM immunochromatographic test (ICT). True sensitivity and specificity of culture (24.4% and 100%), 56kDa PCR assay (56.8% and 98.4%), 47kDa PCR assay (63.2% and 96.1%), groEL PCR assay (71.4% and 93.0%), IFA IgM (70.0% and 83.8%), PanBio IgM ICT (72.8% and 96.8%), presence of eschar (42.7% and 98.9%) and STIC (90.5% and 82.5%) estimated by Bayesian LCM were considerably different from those obtained when using STIC as a reference standard. The IgM ICT had comparable sensitivity and significantly higher specificity compared to IFA (p=0.34 and p<0.001, respectively).
The low specificity of STIC was caused by the low specificity of IFA IgM. Neither STIC nor IFA IgM can be used as reference standards against which to evaluate alternative diagnostic tests. Further evaluation of new diagnostic tests should be done with a carefully selected set of diagnostic tests and appropriate statistical models.
PMCID: PMC4449177  PMID: 26024375
6.  Mortality Attributable to Seasonal Influenza A and B Infections in Thailand, 2005–2009: A Longitudinal Study 
American Journal of Epidemiology  2015;181(11):898-907.
Influenza epidemiology differs substantially in tropical and temperate zones, but estimates of seasonal influenza mortality in developing countries in the tropics are lacking. We aimed to quantify mortality due to seasonal influenza in Thailand, a tropical middle-income country. Time series of polymerase chain reaction–confirmed influenza infections between 2005 and 2009 were constructed from a sentinel surveillance network. These were combined with influenza-like illness data to derive measures of influenza activity and relationships to mortality by using a Bayesian regression framework. We estimated 6.1 (95% credible interval: 0.5, 12.4) annual deaths per 100,000 population attributable to influenza A and B, predominantly in those aged ≥60 years, with the largest contribution from influenza A(H1N1) in 3 out of 4 years. For A(H3N2), the relationship between influenza activity and mortality varied over time. Influenza was associated with increases in deaths classified as resulting from respiratory disease (posterior probability of positive association, 99.8%), cancer (98.6%), renal disease (98.0%), and liver disease (99.2%). No association with circulatory disease mortality was found. Seasonal influenza infections are associated with substantial mortality in Thailand, but evidence for the strong relationship between influenza activity and circulatory disease mortality reported in temperate countries is lacking.
PMCID: PMC4445392  PMID: 25899091
Bayesian regression; burden; developing country; influenza; middle-income country; mortality; seasonal variation; tropics
7.  Public Awareness of Melioidosis in Thailand and Potential Use of Video Clips as Educational Tools 
PLoS ONE  2015;10(3):e0121311.
Melioidosis causes more than 1,000 deaths in Thailand each year. Infection occurs via inoculation, ingestion or inhalation of the causative organism (Burkholderia pseuodmallei) present in soil and water. Here, we evaluated public awareness of melioidosis using a combination of population-based questionnaire, a public engagement campaign to obtain video clips made by the public, and viewpoints on these video clips as potential educational tools about the disease and its prevention.
A questionnaire was developed to evaluate public awareness of melioidosis, and knowledge about its prevention. From 1 March to 31 April 2012, the questionnaire was delivered to five randomly selected adults in each of 928 districts in Thailand. A video clip contest entitled “Melioidosis, an infectious disease that Thais must know” was run between May and October 2012. The best 12 video clips judged by a contest committee were shown to 71 people at risk from melioidosis (diabetics). Focus group interviews were used to evaluate their perceptions of the video clips.
Of 4,203 Thais who completed our study questionnaire, 74% had never heard of melioidosis, and 19% had heard of the disease but had no further knowledge. Most participants in all focus group sessions felt that video clips were beneficial and could positively influence them to increase adherence to recommended preventive behaviours, including drinking boiled water and wearing protective gear if in contact with soil or environmental water. Participants suggested that video clips should be presented in the local dialect with simple words rather than medical terms, in a serious manner, with a doctor as the one presenting the facts, and having detailed pictures of each recommended prevention method.
In summary, public awareness of melioidosis in Thailand is very low, and video clips could serve as a useful medium to educate people and promote disease prevention.
Presented in Part
World Melioidosis Congress 2013, Bangkok, Thailand, 18–20 September 2013 (abstract OS VII-04).
PMCID: PMC4372587  PMID: 25803048
8.  Melioidosis Diagnostic Workshop, 20131 
Emerging Infectious Diseases  2015;21(2):e141045.
Melioidosis is a severe disease that can be difficult to diagnose because of its diverse clinical manifestations and a lack of adequate diagnostic capabilities for suspected cases. There is broad interest in improving detection and diagnosis of this disease not only in melioidosis-endemic regions but also outside these regions because melioidosis may be underreported and poses a potential bioterrorism challenge for public health authorities. Therefore, a workshop of academic, government, and private sector personnel from around the world was convened to discuss the current state of melioidosis diagnostics, diagnostic needs, and future directions.
PMCID: PMC4313648  PMID: 25626057
melioidosis; Burkholderia pseudomallei; diagnosis; bacteria
9.  Clinical and Molecular Epidemiology of Staphylococcus argenteus Infections in Thailand 
Journal of Clinical Microbiology  2015;53(3):1005-1008.
Molecular typing of 246 Staphylococcus aureus isolates from unselected patients in Thailand showed that 10 (4.1%) were actually Staphylococcus argenteus. Contrary to the suggestion that S. argenteus is less virulent than S. aureus, we demonstrated comparable rates of morbidity, death, and health care-associated infection in patients infected with either of these two species.
PMCID: PMC4390622  PMID: 25568440
10.  Clinical, Environmental, and Serologic Surveillance Studies of Melioidosis in Gabon, 2012–2013 
Emerging Infectious Diseases  2015;21(1):40-47.
Burkholderia pseudomallei and B. thailandensis are in the soil; a novel B. pseudomallei sequence type causes lethal septic shock.
Burkholderia pseudomallei, an environmental gram-negative bacillus, is the causative agent of melioidosis and a bio-threat agent. Reports of B. pseudomallei isolation from soil and animals in East and West Africa suggest that melioidosis might be more widely distributed than previously thought. Because it has been found in equatorial areas with tropical climates, we hypothesized that B. pseudomallei could exist in Gabon. During 2012–2013, we conducted a seroprevalance study in which we set up microbiology facilities at a large clinical referral center and prospectively screened all febrile patients by conducting blood cultures and testing for B. pseudomallei and related species; we also determined whether B. pseudomallei could be isolated from soil. We discovered a novel B. pseudomallei sequence type that caused lethal septic shock and identified B. pseudomallei and B. thailandensis in the environment. Our data suggest that melioidosis is emerging in Central Africa but is unrecognized because of the lack of diagnostic microbiology facilities.
PMCID: PMC4285261  PMID: 25530077
Burkholderia pseudomallei; Burkholderia thailandensis; melioidosis; epidemiology; seroprevalance; Africa; Gabon; soil; sepsis; bacteria
11.  Failure of Burkholderia pseudomallei to Grow in an Automated Blood Culture System 
We compared the organisms isolated from 30,210 pairs of blood culture bottles by using BacT/Alert system and the conventional system. Overall, 2,575 (8.5%) specimens were culture positive for pathogenic organisms. The sensitivity for detection of pathogenic organisms with the BACT/Alert system (85.6%, 2,203 of 2,575) was significantly higher than that with the conventional method (74.1%, 1,908 of 2,575; P < 0.0001). However, Burkholderia pseudomallei was isolated less often with the BacT/ALERT system (73.5%, 328 of 446) than with the conventional system (90.3%, 403 of 446; P < 0.0001). This finding suggests that use of the conventional culture method in conjunction with the BacT/Alert system may improve the isolation rate for B. pseudomallei in melioidosis-endemic areas.
PMCID: PMC4257642  PMID: 25311697
12.  Maintenance of Leptospira Species in Leptospira Vanaporn Wuthiekanun Agar 
Journal of Clinical Microbiology  2014;52(12):4350-4352.
The maintenance of Leptospira species in liquid or semisolid medium is time-consuming and at risk of contamination due to the needs of routine subculture and dark field microscopy. Using Leptospira Vanaporn Wuthiekanun (LVW) agar, we maintained 100 pathogenic Leptospira isolates for 12 months without the need for subculture and confirmed the viability of all isolates by the naked eye.
PMCID: PMC4313312  PMID: 25253789
13.  Burkholderia pseudomallei in Water Supplies, Southern Thailand 
Emerging Infectious Diseases  2014;20(11):1947-1949.
PMCID: PMC4215545  PMID: 25340393
melioidosis; B. pseudomallei; water; Phangan; Thailand; bacteria; Koh Phangan
14.  Increasing Incidence of Hospital-Acquired and Healthcare-Associated Bacteremia in Northeast Thailand: A Multicenter Surveillance Study 
PLoS ONE  2014;9(10):e109324.
Little is known about the epidemiology of nosocomial bloodstream infections in public hospitals in developing countries. We evaluated trends in incidence of hospital-acquired bacteremia (HAB) and healthcare-associated bacteremia (HCAB) and associated mortality in a developing country using routinely available databases.
Information from the microbiology and hospital databases of 10 provincial hospitals in northeast Thailand was linked with the national death registry for 2004–2010. Bacteremia was considered hospital-acquired if detected after the first two days of hospital admission, and healthcare-associated if detected within two days of hospital admission with a prior inpatient episode in the preceding 30 days.
A total of 3,424 patients out of 1,069,443 at risk developed HAB and 2,184 out of 119,286 at risk had HCAB. Of these 1,559 (45.5%) and 913 (41.8%) died within 30 days, respectively. Between 2004 and 2010, the incidence rate of HAB increased from 0.6 to 0.8 per 1,000 patient-days at risk (p<0.001), and the cumulative incidence of HCAB increased from 1.2 to 2.0 per 100 readmissions (p<0.001). The most common causes of HAB were Acinetobacter spp. (16.2%), Klebsiella pneumoniae (13.9%), and Staphylococcus aureus (13.9%), while those of HCAB were Escherichia coli (26.3%), S. aureus (14.0%), and K. pneumoniae (9.7%). There was an overall increase over time in the proportions of ESBL-producing E. coli causing HAB and HCAB.
This study demonstrates a high and increasing incidence of HAB and HCAB in provincial hospitals in northeast Thailand, increasing proportions of ESBL-producing isolates, and very high associated mortality.
PMCID: PMC4195656  PMID: 25310563
15.  NLRC4 and TLR5 Each Contribute to Host Defense in Respiratory Melioidosis 
Burkholderia pseudomallei causes the tropical infection melioidosis. Pneumonia is a common manifestation of melioidosis and is associated with high mortality. Understanding the key elements of host defense is essential to developing new therapeutics for melioidosis. As a flagellated bacterium encoding type III secretion systems, B. pseudomallei may trigger numerous host pathogen recognition receptors. TLR5 is a flagellin sensor located on the plasma membrane. NLRC4, along with NAIP proteins, assembles a canonical caspase-1-dependent inflammasome in the cytoplasm that responds to flagellin (in mice) and type III secretion system components (in mice and humans). In a murine model of respiratory melioidosis, Tlr5 and Nlrc4 each contributed to survival. Mice deficient in both Tlr5 and Nlrc4 were not more susceptible than single knockout animals. Deficiency of Casp1/Casp11 resulted in impaired bacterial control in the lung and spleen; in the lung much of this effect was attributable to Nlrc4, despite relative preservation of pulmonary IL-1β production in Nlrc4−/− mice. Histologically, deficiency of Casp1/Casp11 imparted more severe pulmonary inflammation than deficiency of Nlrc4. The human NLRC4 region polymorphism rs6757121 was associated with survival in melioidosis patients with pulmonary involvement. Co-inheritance of rs6757121 and a functional TLR5 polymorphism had an additive effect on survival. Our results show that NLRC4 and TLR5, key components of two flagellin sensing pathways, each contribute to host defense in respiratory melioidosis.
Author Summary
Melioidosis is an infection caused by Burkholderia pseudomallei, a bacterium that is found in tropical soil and water. Melioidosis can present in a variety of ways, but lung involvement is common and usually severe. The host response to infection governs outcome. In this study, we examined the role of two host sensors of bacterial components–TLR5 and NLRC4–to determine their necessity in respiratory melioidosis. Although both proteins are involved in detection of bacterial flagellin, in mice we defined specific and individual roles for TLR5 and NLRC4 in protecting against death from melioidosis. In humans with melioidosis involving the lung, genetic variation in these receptors also had independent associations with survival. These results underscore the importance of these elements of host defense in respiratory melioidosis and support further studies of the underlying mechanisms.
PMCID: PMC4169243  PMID: 25232720
16.  Microevolution of Burkholderia pseudomallei during an Acute Infection 
Journal of Clinical Microbiology  2014;52(9):3418-3421.
We used whole-genome sequencing to evaluate 69 independent colonies of Burkholderia pseudomallei isolated from seven body sites of a patient with acute disseminated melioidosis. Fourteen closely related genotypes were found, providing evidence for the rapid in vivo diversification of B. pseudomallei after inoculation and systemic spread.
PMCID: PMC4313173  PMID: 24966357
17.  Fatal Melioidosis in Goats in Bangkok, Thailand 
Bangkok, Thailand, is a city considered to be at low risk for melioidosis. We describe 10 goats that died of melioidosis in Bangkok. Half of them were born and reared in the city. Multilocus sequence typing ruled out an outbreak. This finding challenges the assumption that melioidosis is rarely acquired in central Thailand.
PMCID: PMC4125250  PMID: 24891468
18.  The role of NOD2 in murine and human melioidosis 
Journal of immunology (Baltimore, Md. : 1950)  2013;192(1):10.4049/jimmunol.1301436.
NOD2 is a cytosolic pathogen recognition receptor that regulates susceptibility to a variety of infections and chronic diseases. Burkholderia pseudomallei, a facultative intracellular bacterium, causes the tropical infection melioidosis. We hypothesized that NOD2 may participate in host defense in melioidosis. We performed a series of in vitro assays and in vivo experiments, and analyzed the association of human genetic variation with infection to delineate the contribution of NOD2 to the host response to B. pseudomallei. We found that transfection with NOD2 mediated NF-κB activation induced by B. pseudomallei stimulation of HEK293 cells. After low dose inoculation with aerosolized B. pseudomallei, Nod2-deficient mice showed impaired clinical responses and permitted greater bacterial replication in the lung and dissemination to the spleen compared to wild type mice. IL-6 and KC levels were higher in the lungs of Nod2-deficient mice. In a cohort of 1,562 Thai subjects, a common genetic polymorphism in the NOD2 region, rs7194886, was associated with melioidosis and this effect was most pronounced in women. rs7194886 was not associated with differences in cytokine production induced by whole blood stimulation with the NOD2 ligand, MDP, or B. pseudomallei. These findings are the first to characterize the role of NOD2 in host defense in mammalian melioidosis.
PMCID: PMC3872087  PMID: 24298015
Burkholderia pseudomallei; melioidosis; NOD2; innate immunity; genetic variation; animal model; pneumonia; sepsis
19.  The role of NOD2 in murine and human melioidosis 
NOD2 is a cytosolic pathogen recognition receptor that regulates susceptibility to a variety of infections and chronic diseases. Burkholderia pseudomallei, a facultative intracellular bacterium, causes the tropical infection melioidosis. We hypothesized that NOD2 may participate in host defense in melioidosis. We performed a series of in vitro assays and in vivo experiments, and analyzed the association of human genetic variation with infection to delineate the contribution of NOD2 to the host response to B. pseudomallei. We found that transfection with NOD2 mediated NF-κB activation induced by B. pseudomallei stimulation of HEK293 cells. After low dose inoculation with aerosolized B. pseudomallei, Nod2-deficient mice showed impaired clinical responses and permitted greater bacterial replication in the lung and dissemination to the spleen compared to wild type mice. IL-6 and KC levels were higher in the lungs of Nod2-deficient mice. In a cohort of 1,562 Thai subjects, a common genetic polymorphism in the NOD2 region, rs7194886, was associated with melioidosis and this effect was most pronounced in women. rs7194886 was not associated with differences in cytokine production induced by whole blood stimulation with the NOD2 ligand, MDP, or B. pseudomallei. These findings are the first to characterize the role of NOD2 in host defense in mammalian melioidosis.
PMCID: PMC3872087  PMID: 24298015
Burkholderia pseudomallei; melioidosis; NOD2; innate immunity; genetic variation; animal model; pneumonia; sepsis
20.  New Insights from the 7th World Melioidosis Congress 2013 
Emerging Infectious Diseases  2014;20(7):e131737.
PMCID: PMC4073878  PMID: 24961743
World Melioidosis Congress 2013; Burkholderia pseudomallei; melioidosis; current challenges; environmental saprophyte; bacterium; resource sharing
21.  Evaluation of a Latex Agglutination Assay for the Identification of Burkholderia pseudomallei and Burkholderia mallei 
Cases of melioidosis and glanders are rare in the United States, but the etiologic agents of each disease (Burkholderia pseudomallei and Burkholderia mallei, respectively) are classified as Tier 1 select agents because of concerns about their potential use as bioterrorism agents. A rapid, highly sensitive, and portable assay for clinical laboratories and field use is required. Our laboratory has further evaluated a latex agglutination assay for its ability to identify B. pseudomallei and B. mallei isolates. This assay uses a monoclonal antibody that specifically recognizes the capsular polysaccharide produced by B. pseudomallei and B. mallei, but is absent in closely related Burkholderia species. A total of 110 B. pseudomallei and B. mallei were tested, and 36 closely related Burkholderia species. The latex agglutination assay was positive for 109 of 110 (99.1% sensitivity) B. pseudomallei and B. mallei isolates tested.
PMCID: PMC4047727  PMID: 24710616
22.  Zero tolerance for healthcare-associated MRSA bacteraemia: is it realistic? 
The term ‘zero tolerance’ has recently been applied to healthcare-associated infections, implying that such events are always preventable. This may not be the case for healthcare-associated infections such as methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia.
We combined information from an epidemiological investigation and bacterial whole-genome sequencing to evaluate a cluster of five MRSA bacteraemia episodes in four patients in a specialist hepatology unit.
The five MRSA bacteraemia isolates were highly related by multilocus sequence type (ST) (four isolates were ST22 and one isolate was a single-locus variant, ST2046). Whole-genome sequencing demonstrated unequivocally that the bacteraemia cases were unrelated. Placing the MRSA bacteraemia isolates within a local and global phylogenetic tree of MRSA ST22 genomes demonstrated that the five bacteraemia isolates were highly diverse. This was consistent with the acquisition and importation of MRSA from the wider referral network. Analysis of MRSA carriage and disease in patients within the hepatology service demonstrated a higher risk of both initial MRSA acquisition compared with the nephrology service and a higher risk of progression from MRSA carriage to bacteraemia, compared with patients in nephrology or geriatric services. A root cause analysis failed to reveal any mechanism by which three of five MRSA bacteraemia episodes could have been prevented.
This study illustrates the complex nature of MRSA carriage and bacteraemia in patients in a specialized hepatology unit. Despite numerous ongoing interventions to prevent MRSA bacteraemia in healthcare settings, these are unlikely to result in a zero incidence in referral centres that treat highly complex patients.
PMCID: PMC4100711  PMID: 24788657
methicillin-resistant Staphylococcus aureus; outbreak; whole-genome sequencing
23.  Development of a Prototype Lateral Flow Immunoassay (LFI) for the Rapid Diagnosis of Melioidosis 
Burkholderia pseudomallei is a soil-dwelling bacterium and the causative agent of melioidosis. Isolation of B. pseudomallei from clinical samples is the “gold standard” for the diagnosis of melioidosis; results can take 3–7 days to produce. Alternatively, antibody-based tests have low specificity due to a high percentage of seropositive individuals in endemic areas. There is a clear need to develop a rapid point-of-care antigen detection assay for the diagnosis of melioidosis. Previously, we employed In vivo Microbial Antigen Discovery (InMAD) to identify potential B. pseudomallei diagnostic biomarkers. The B. pseudomallei capsular polysaccharide (CPS) and numerous protein antigens were identified as potential candidates. Here, we describe the development of a diagnostic immunoassay based on the detection of CPS. Following production of a CPS-specific monoclonal antibody (mAb), an antigen-capture immunoassay was developed to determine the concentration of CPS within a panel of melioidosis patient serum and urine samples. The same mAb was used to produce a prototype Active Melioidosis Detect Lateral Flow Immunoassay (AMD LFI); the limit of detection of the LFI for CPS is comparable to the antigen-capture immunoassay (∼0.2 ng/ml). The analytical reactivity (inclusivity) of the AMD LFI was 98.7% (76/77) when tested against a large panel of B. pseudomallei isolates. Analytical specificity (cross-reactivity) testing determined that 97.2% of B. pseudomallei near neighbor species (35/36) were not reactive. The non-reactive B. pseudomallei strain and the reactive near neighbor strain can be explained through genetic sequence analysis. Importantly, we show the AMD LFI is capable of detecting CPS in a variety of patient samples. The LFI is currently being evaluated in Thailand and Australia; the focus is to optimize and validate testing procedures on melioidosis patient samples prior to initiation of a large, multisite pre-clinical evaluation.
Author Summary
Burkholderia pseudomallei is an environmental bacterium and the cause of melioidosis. Culture of patient samples is the “gold standard” diagnostic test, but may take up to 7 days to complete. Melioidosis has a 10–40% case fatality rate depending on the geographic location. Delays in diagnosis could lead to administration of ineffective antimicrobial therapy, since B. pseudomallei is resistant to empiric antibiotic regimens. Therefore, we have developed a lateral flow immunoassay that can be used in the clinical setting to diagnose melioidosis in 15 minutes. The test promises to provide improved management of patients with melioidosis.
PMCID: PMC3961207  PMID: 24651568
24.  Trimethoprim-sulfamethoxazole versus trimethoprim-sulfamethoxazole plus doxycycline as oral eradicative treatment for melioidosis (MERTH): a multicentre, double-blind, non-inferiority, randomised controlled trial 
Lancet  2014;383(9919):807-814.
Melioidosis, an infectious disease caused by the Gram-negative bacillus Burkholderia pseudomallei, is difficult to cure. Antimicrobial treatment comprises intravenous drugs for at least 10 days, followed by oral drugs for at least 12 weeks. The standard oral regimen based on trial evidence is trimethoprim-sulfamethoxaxole (TMP-SMX) plus doxycycline. This regimen is used in Thailand but is associated with side-effects and poor adherence by patients, and TMP-SMX alone is recommended in Australia. We compared the efficacy and side-effects of TMP-SMX with TMP-SMX plus doxycycline for the oral phase of melioidosis treatment.
For this multi-centre, double-blind, non-inferiority, randomised placebo-controlled trial, we enrolled patients (aged ≥15 years) from five centres in northeast Thailand with culture-confirmed melioidosis who had received a course of parenteral antimicrobial drugs. Using a computer-generated sequence, we randomly assigned patients to receive TMP-SMX plus placebo or TMP-SMX plus doxycycline for 20 weeks (1:1; block size of ten, stratified by study site). We followed patients up every 4 months for 1 year and annually thereafter to the end of the study. The primary endpoint was culture-confirmed recurrent melioidosis, and the non-inferiority margin was a hazard ratio (HR) of 1·7. This study is registered with, number ISRCTN86140460.
We enrolled and randomly assigned 626 patients: 311 to TMP-SMX plus placebo and 315 to TMP-SMX plus doxycycline. 16 patients (5%) in the TMP-SMX plus placebo group and 21 patients (7%) in the TMP-SMX plus doxycycline group developed culture-confirmed recurrent melioidosis (HR 0·81; 95% CI 0·42–1·55). The criterion for non-inferiority was met (p=0.01). Adverse drug reactions were less common in the TMP-SMX plus placebo group than in the TMP-SMX plus doxycycline group (122 [39%] vs 167 [53%]).
Our findings suggest that TMP-SMX is not inferior to TMP-SMX plus doxycycline for the oral phase of melioidosis treatment, and is preferable on the basis of safety and tolerance by patients.
Thailand Research Fund, the Melioidosis Research Center, the Center of Excellence in Specific Health Problems in Greater Mekong Sub-region cluster, and the Wellcome Trust.
PMCID: PMC3939931  PMID: 24284287

Results 1-25 (98)