To determine risk factors and clinical signs that may differentiate between bacterial, fungal, and acanthamoeba keratitis among patients presenting with presumed infectious keratitis.
Hospital-based cross-sectional study.
We examined the medical records of 115 patients with laboratory-proven bacterial keratitis, 115 patients with laboratory-proven fungal keratitis, and 115 patients with laboratory-proven acanthamoeba keratitis seen at Aravind Eye Hospital, Madurai, India, from 2006–2011. Risk factors and clinical features of the three organisms were compared using multinomial logistic regression.
Of 95 patients with bacterial keratitis, 103 patients with fungal keratitis, and 93 patients with acanthamoeba keratitis who had medical records available for review, 287 (99%) did not wear contact lenses. Differentiating features were more common for acanthamoeba keratitis than for bacterial or fungal keratitis. Compared to patients with bacterial or fungal keratitis, patients with acanthamoeba keratitis were more likely to be younger and to have a longer duration of symptoms, and to have a ring infiltrate or disease confined to the epithelium.
Risk factors and clinical examination findings can be useful for differentiating acanthamoeba keratitis from bacterial and fungal keratitis.
risk factors; disease attributes; India; corneal ulcer
Scarring from bacterial keratitis remains a leading cause of visual loss.
To determine whether topical corticosteroids are beneficial as an adjunctive therapy for bacterial keratitis if given early in the course of infection.
DESIGN, SETTING, AND PARTICIPANTS
The Steroids for Corneal Ulcers Trial (SCUT) was a randomized, double-masked, placebo-controlled trial that overall found no effect of adding topical corticosteroids to topical moxifloxacin hydrochloride in bacterial keratitis. Here, we assess the timing of administration of corticosteroids in a subgroup analysis of the SCUT. We define earlier administration of corticosteroids (vs placebo) as addition after 2 to 3 days of topical antibiotics and later as addition after 4 or more days of topical antibiotics.
MAIN OUTCOMES AND MEASURES
We assess the effect of topical corticosteroids (vs placebo) on 3-month best spectacle-corrected visual acuity in patients who received corticosteroids or placebo earlier vs later. Further analyses were performed for subgroups of patients with non-Nocardia keratitis and those with no topical antibiotic use before enrollment.
Patients treated with topical corticosteroids as adjunctive therapy within 2 to 3 days of antibiotic therapy had approximately 1-line better visual acuity at 3 months than did those given placebo (−0.11 logMAR; 95% CI, −0.20 to −0.02 logMAR; P = .01). In patients who had 4 or more days of antibiotic therapy before corticosteroid treatment, the effect was not significant; patients given corticosteroids had 1-line worse visual acuity at 3 months compared with those in the placebo group (0.10 logMAR; 95% CI, −0.02 to 0.23 logMAR; P = .14). Patients with non-Nocardia keratitis and those having no topical antibiotic use before the SCUT enrollment showed significant improvement in best spectacle-corrected visual acuity at 3 months if corticosteroids were administered earlier rather than later.
CONCLUSIONS AND RELEVANCE
There may be a benefit with adjunctive topical corticosteroids if application occurs earlier in the course of bacterial corneal ulcers.
Mass administration of azithromycin for trachoma has been shown to reduce malarial parasitemia. However, the optimal seasonal timing of such distributions for antimalarial benefit has not been established. We performed numerical analyses on a seasonally forced epidemic model (of Ross-Macdonald type) with periodic impulsive annual mass treatment to address this question. We conclude that when azithromycin-based trachoma elimination programs occur in regions of seasonal malaria transmission, such as Niger, the optimal seasonal timing of mass drug administration (MDA) may not occur during the season of maximum transmission.
We described the change in visual acuity experienced by eyes successfully treated for bacterial keratitis.
This was a prospective cohort study of a subset of study participants who had previously enrolled in the Steroids for Corneal Ulcers Trial (SCUT). All study participants had been diagnosed with culture-proven bacterial keratitis before enrollment in SCUT and subsequently were randomized to adjunctive topical corticosteroids or placebo. During SCUT, we monitored study participants at enrollment, 3 weeks, 3 months, and 12 months. We invited a subset to complete a comprehensive eye examination approximately 4 years after enrollment in SCUT. Certified refractionists assessed best spectacle-corrected visual acuity (BSCVA) using the same protocol at each study visit.
We examined 50 SCUT participants at 4 years after enrollment. Among those in this cohort, mean logMAR BSCVA at enrollment was 0.85 (Snellen equivalent, 20/160; 95% confidence interval [CI], 0.71–0.99). On average, visual acuity improved by 2.9 logMAR lines from enrollment to 3 weeks (P < 0.001), 1.2 lines from 3 weeks to 3 months (P = 0.002), and 0.8 lines from 3 to 12 months (P = 0.01). The BSCVA did not change significantly between 12 months and 4 years (0.04-line improvement, P = 0.88). After controlling for visual acuity at enrollment, BSCVA was not significantly different between the corticosteroid and placebo groups at 4 years (P = 0.53).
Cases of bacterial keratitis may continue to demonstrate improvements in visual acuity up to 12 months following diagnosis, but further improvements are unlikely. These findings may guide the appropriate timing of surgical intervention in these patients. (ClinicalTrials.gov number, NCT00324168.)
In a subset of study participants from the Steroids for Corneal Ulcers trial (SCUT), best spectacle corrected visual acuity improved from enrollment to the 3-month study visit, and from the 3- to 12-month study visits, but not from the 12-month to 4-year study visits.
prospective; visual acuity; long-term; outcomes; keratitis; clinical trial
Latrine use has been promoted as a component of an integrated strategy for trachoma control. As part of a randomized trial in Ethiopia, 12 communities received a mass azithromycin distribution followed by a latrine promotion intervention. A random sample of children ages 0–9 years in each community was monitored longitudinally for ocular chlamydia. After latrine construction ended, those communities with a higher proportion of households using latrines were more likely to experience a reduction in the prevalence of ocular chlamydia. Specifically, for each 10% increase in latrine use, there was a 2.0% decrease (95% confidence interval = 0.2–3.9% decrease) in the community prevalence of ocular chlamydia over the subsequent year (P = 0.04).
Antibiotic use on animals demonstrates improved growth regardless of whether or not there is clinical evidence of infectious disease. Antibiotics used for trachoma control may play an unintended benefit of improving child growth.
In this sub-study of a larger randomized controlled trial, we assess anthropometry of pre-school children in a community-randomized trial of mass oral azithromycin distributions for trachoma in Niger. We measured height, weight, and mid-upper arm circumference (MUAC) in 12 communities randomized to receive annual mass azithromycin treatment of everyone versus 12 communities randomized to receive biannual mass azithromycin treatments for children, 3 years after the initial mass treatment. We collected measurements in 1,034 children aged 6–60 months of age.
We found no difference in the prevalence of wasting among children in the 12 annually treated communities that received three mass azithromycin distributions compared to the 12 biannually treated communities that received six mass azithromycin distributions (odds ratio = 0.88, 95% confidence interval = 0.53 to 1.49).
We were unable to demonstrate a statistically significant difference in stunting, underweight, and low MUAC of pre-school children in communities randomized to annual mass azithromycin treatment or biannual mass azithromycin treatment. The role of antibiotics on child growth and nutrition remains unclear, but larger studies and longitudinal trials may help determine any association.
Recent studies suggest that antibiotic use could have an effect on growth in humans. Azithromycin is an antibiotic used for trachoma control, and hence, may have an unintended benefit of improving child growth. Niger is a trachoma-endemic country where mass antibiotic distributions for trachoma take place and where malnutrition is widespread among children. In addition, azithromycin may have an effect on common childhood diseases associated with malnutrition, such as diarrhea, pneumonia, and malaria. In a community-randomized trachoma trial in Matameye, Niger, we assessed child growth by measuring height, weight, and mid-upper arm circumference of pre-school children who have received 3 years of annual or biannual mass azithromycin treatment. While these measures were better in the biannually treated communities, the difference was not statistically significant. Thus, further research will help determine the impact of antibiotics on child growth and nutrition.
Background. Many believe antibiotic use results in a tragedy of the commons, since overuse may lead to antibiotic resistance and limiting use would benefit society. In contrast, mass antibiotic treatment programs are thought to result in community-wide benefits. A survey was conducted to learn the views of infectious disease experts on the individual- and societal-level consequences of antibiotic use. Methods. The survey instrument was designed to elicit opinions on antibiotic use and resistance. It was sent via SurveyMonkey to infectious disease professionals identified through literature searches. Descriptive statistics were used to analyze the data. Results. A total of 1,530 responses were received for a response rate of 9.9%. Nearly all participants believed antibiotic use could result in a tragedy of the commons, at least in certain circumstances (96.0%). Most participants did not believe mass antibiotic treatment programs could produce societal benefits in an antibiotic-free society (91.4%) or in the United States (94.2%), though more believed such programs would benefit antibiotic-free societies compared to the United States (P < 0.001). Conclusions. The experts surveyed believe that antibiotic use can result in a tragedy of the commons and do not believe that mass treatment programs benefit individuals or society.
To perform a Bayesian analysis of the Mycotic Ulcer Treatment Trial I (MUTT I) using expert opinion as a prior belief.
MUTT I was a randomized clinical trial comparing topical natamycin or voriconazole for treating filamentous fungal keratitis. A questionnaire elicited expert opinion on the best treatment of fungal keratitis before MUTT I results were available. A Bayesian analysis was performed using the questionnaire data as a prior belief and the MUTT I primary outcome (3-month visual acuity) by frequentist analysis as a likelihood.
Corneal experts had a 41.1% prior belief that natamycin improved 3-month visual acuity compared with voriconazole. The Bayesian analysis found a 98.4% belief for natamycin treatment compared with voriconazole treatment for filamentous cases as a group (mean improvement 1.1 Snellen lines, 95% credible interval 0.1–2.1). The Bayesian analysis estimated a smaller treatment effect than the MUTT I frequentist analysis result of 1.8-line improvement with natamycin versus voriconazole (95% confidence interval 0.5–3.0, P = 0.006). For Fusarium cases, the posterior demonstrated a 99.7% belief for natamycin treatment, whereas non-Fusarium cases had a 57.3% belief.
The Bayesian analysis suggests that natamycin is superior to voriconazole when filamentous cases are analyzed as a group. Subgroup analysis of Fusarium cases found improvement with natamycin compared with voriconazole, whereas there was almost no difference between treatments for non-Fusarium cases. These results were consistent with, though smaller in effect size than, the MUTT I primary outcome by frequentist analysis. The accordance between analyses further validates the trial results. (ClinicalTrials.gov number, NCT00996736.)
We elicited the opinions of corneal specialists on treating filamentous fungal keratitis, to perform a Bayesian analysis of the Mycotic Ulcer Treatment Trial I. The Bayesian analysis result was consistent with, but suggested a smaller treatment effect than, the frequentist result.
fungal keratitis; corneal ulceration; clinical trial; Bayesian; statistics
To analyze the relationship between fluoroquinolone use at presentation and minimum inhibitory concentration in bacterial keratitis.
The Steroids for Corneal Ulcers Trial was a randomized, double-masked, placebo-controlled trial assessing the effect of adjunctive topical corticosteroid treatment on outcomes in bacterial keratitis. After presentation, all patients were treated with moxifloxacin hydrochloride, 0.5%. We compare antibiotic use at presentation with minimum inhibitory concentration against moxifloxacin for all isolates. Separate analyses accounted for organism species and fluoroquinolone generation.
Topical fluoroquinolone use at presentation was reported in 92 of 480 cases (19.2%). Causative organisms in the 480 cases included Streptococcus pneumoniae (247 cases [51.5%]), Pseudomonas aeruginosa (109 cases [22.7%]), and Nocardia species (55 cases [11.5%]). Isolates from patients who reported fluoroquinolone use at presentation had a 2.01-fold–higher minimum inhibitory concentration (95% CI, 1.39-fold to 2.91-fold; P <.001). Fourth-generation fluoroquinolones were associated with a 3.48-fold–higher minimum inhibitory concentration than those isolates that were not exposed to pretreatment at enrollment (95% CI, 1.99-fold to 6.06-fold; P <.001).
This study provides evidence that prior use of fluoroquinolones is associated with antibiotic resistance.
To elicit expert opinion on the use of adjunctive corticosteroid therapy in bacterial corneal ulcers. To perform a Bayesian analysis of the Steroids for Corneal Ulcers Trial (SCUT), using expert opinion as a prior probability.
The SCUT was a placebo-controlled trial assessing visual outcomes in patients receiving topical corticosteroids or placebo as adjunctive therapy for bacterial keratitis. Questionnaires were conducted at scientific meetings in India and North America to gauge expert consensus on the perceived benefit of corticosteroids as adjunct treatment. Bayesian analysis, using the questionnaire data as a prior probability and the primary outcome of SCUT as a likelihood, was performed. For comparison, an additional Bayesian analysis was performed using the results of the SCUT pilot study as a prior distribution.
Indian respondents believed there to be a 1.21 Snellen line improvement, and North American respondents believed there to be a 1.24 line improvement with corticosteroid therapy. The SCUT primary outcome found a non-significant 0.09 Snellen line benefit with corticosteroid treatment. The results of the Bayesian analysis estimated a slightly greater benefit than did the SCUT primary analysis (0.19 lines verses 0.09 lines).
Indian and North American experts had similar expectations on the effectiveness of corticosteroids in bacterial corneal ulcers; that corticosteroids would markedly improve visual outcomes. Bayesian analysis produced results very similar to those produced by the SCUT primary analysis. The similarity in result is likely due to the large sample size of SCUT and helps validate the results of SCUT.
Bacterial keratitis; Corneal ulcer; Clinical trial; Statistics; Prior distribution
To describe temporal trends in Pseudomonas aeruginosa resistance to moxifloxacin in keratitis isolates from South India.
The Steroids for Corneal Ulcers Trial (SCUT) was a randomized, double-masked, placebo-controlled trial assessing outcomes in patients with culture positive bacterial corneal ulcers randomized to receive prednisolone phosphate or placebo. All patients received moxifloxacin, and susceptibility to moxifloxacin was measured at baseline using Etest. We investigated trends in moxifloxacin susceptibility of P. aeruginosa during 2007, 2008, and 2009 isolated in SCUT in South India.
There were 89 P. aeruginosa isolates during 2007, 2008, and 2009 in SCUT that were eligible for this study. There was an increase in the proportion of resistant isolates from 19% in 2007 to 52% in 2009 (P=0.02, Chi-square test for trend). Logistic regression showed that there was a 2-fold increase in odds of resistance per one year increase during the study period (OR 2.16, 95% CI 1.09 to 4.26, P=0.027).
We found a sharp increase in the proportion of isolates that were resistant to moxifloxacin from 2007 to 2009. Further work needs to be done to characterize the nature of this increase.
To compare topical natamycin vs voriconazole in the treatment of filamentous fungal keratitis.
This phase 3, double-masked, multicenter trial was designed to randomize 368 patients to voriconazole (1%) or natamycin (5%), applied topically every hour while awake until reepithelialization, then 4 times daily for at least 3 weeks. Eligibility included smear-positive filamentous fungal ulcer and visual acuity of 20/40 to 20/400.
Main Outcome Measures
The primary outcome was best spectacle-corrected visual acuity at 3 months; secondary outcomes included corneal perforation and/or therapeutic penetrating keratoplasty.
A total of 940 patients were screened and 323 were enrolled. Causative organisms included Fusarium (128 patients [40%]), Aspergillus (54 patients [17%]), and other filamentous fungi (141 patients [43%]). Natamycin-treated cases had significantly better 3-month best spectacle-corrected visual acuity than voriconazole-treated cases (regression coefficient=−0.18 logMAR; 95% CI, −0.30 to −0.05; P=.006). Natamycin-treated cases were less likely to have perforation or require therapeutic penetrating keratoplasty (odds ratio=0.42; 95% CI, 0.22 to 0.80; P=.009). Fusarium cases fared better with natamycin than with voriconazole (regression coefficient=−0.41 logMAR; 95% CI, −0.61 to −0.20; P<.001; odds ratio for perforation=0.06; 95% CI, 0.01 to 0.28; P<.001), while non-Fusarium cases fared similarly (regression coefficient=−0.02 logMAR; 95% CI, −0.17 to 0.13; P=.81; odds ratio for perforation=1.08; 95% CI, 0.48 to 2.43; P=.86).
Natamycin treatment was associated with significantly better clinical and microbiological outcomes than voriconazole treatment for smear-positive filamentous fungal keratitis, with much of the difference attributable to improved results in Fusarium cases.
Application to Clinical Practice
Voriconazole should not be used as monotherapy in filamentous keratitis.
clinicaltrials.gov Identifier: NCT00996736
Clinical examination of trachoma is used to justify intervention in trachoma-endemic regions. Currently, field graders are certified by determining their concordance with experienced graders using the kappa statistic. Unfortunately, trachoma grading can be highly variable and there are cases where even expert graders disagree (borderline/marginal cases). Prior work has shown that inclusion of borderline cases tends to reduce apparent agreement, as measured by kappa. Here, we confirm those results and assess performance of trainees on these borderline cases by calculating their reliability error, a measure derived from the decomposition of the Brier score.
Methods and Findings
We trained 18 field graders using 200 conjunctival photographs from a community-randomized trial in Niger and assessed inter-grader agreement using kappa as well as reliability error. Three experienced graders scored each case for the presence or absence of trachomatous inflammation - follicular (TF) and trachomatous inflammation - intense (TI). A consensus grade for each case was defined as the one given by a majority of experienced graders. We classified cases into a unanimous subset if all 3 experienced graders gave the same grade. For both TF and TI grades, the mean kappa for trainees was higher on the unanimous subset; inclusion of borderline cases reduced apparent agreement by 15.7% for TF and 12.4% for TI. When we assessed the breakdown of the reliability error, we found that our trainees tended to over-call TF grades and under-call TI grades, especially in borderline cases.
The kappa statistic is widely used for certifying trachoma field graders. Exclusion of borderline cases, which even experienced graders disagree on, increases apparent agreement with the kappa statistic. Graders may agree less when exposed to the full spectrum of disease. Reliability error allows for the assessment of these borderline cases and can be used to refine an individual trainee's grading.
Trachoma is the leading infectious cause of blindness and the World Health Organization plans to eliminate it as a public health concern worldwide by the year 2020. This effort in large part involves mass oral antibiotic distributions to communities. A simplified trachoma grading scale is used to assess presence of active infection. Field workers must be properly trained and certified to perform these eye exams because their findings inform when to start and stop community-wide antibiotic treatments. Certification involves measuring agreement in trachoma grades between a trainee and an experienced grader on a test-set of trachoma photographs. Often, these test-sets have hard-to-grade cases of trachoma removed. We found that removing these borderline cases inflates agreement. Including these borderline cases in the test-set allows a more realistic estimate of agreement, but it is still difficult to assess a trainee's grades for cases which even experts disagree on. We found that reliability error, a measure derived from the decomposition of the Brier score (the mean squared error of a set of forecasts), can be used to assess a trainee's evaluation of these borderline cases.
To determine the relationship between type three secretion genotype and fluoroquinolone resistance for P. aeruginosa strains isolated from microbial keratitis during the Steroids for Corneal Ulcers Trial (SCUT) and for two laboratory strains, PA103 and PAO1.
Confirmed P. aeruginosa isolates from the SCUT were divided into exoU(+) or exoU(−). The exoU(+) strains contained the gene encoding ExoU, a powerful phospholipase toxin delivered into host cells by the type three secretion system. Isolates were then assessed for susceptibility to fluoroquinolone, cephalosporin, and aminoglycoside antibiotics using disk diffusion assays. Etest was used to determine the MIC of moxifloxacin and other fluoroquinolones. Laboratory isolates in which the exoU gene was added or deleted were also tested.
A significantly higher proportion of exoU(+) strains were resistant to ciprofloxacin (p = 0.001), gatifloxacin (p = 0.003), and ofloxacin (p = 0.002) compared to exoU(−) isolates. There was no significant difference between exoU(+) or exoU(−) negative isolates with respect to susceptibility to other antibiotics except gentamicin. Infections involving resistant exoU(+) strains trended towards worse clinical outcome. Deletion or acquisition of exoU in laboratory isolates did not affect fluoroquinolone susceptibility.
Fluoroquinolone susceptibility of P. aeruginosa isolated from the SCUT is consistent with previous studies showing elevated resistance involving exoU encoding (cytotoxic) strains, and suggest worse clinical outcome from infections involving resistant isolates. Determination of exoU expression in clinical isolates of P. aeruginosa may be helpful in directing clinical management of patients with microbial keratitis.
P. aeruginosa; Microbial keratitis; SCUT; Fluoroquinolone resistance; ExoU
Bacterial keratitis is a sight-threatening infection of the cornea that is one of the leading causes of blindness globally. In this report, we analyze the role of moxifloxacin susceptibility in the relationship between causative organisms and clinical outcome in bacteria keratitis.
A mediation analysis is used to assess the role of moxifloxacin susceptibility in the relationship between causative organisms and clinical outcome in bacterial keratitis using data collected in a randomized, controlled trial.
In the Steroids for Corneal Ulcers Trial (SCUT), 500 corneal infections were treated with topical moxifloxacin. The outcome of 3-week best spectacle-corrected visual acuity was significantly associated with an organism (Streptococcus pneumoniae, Pseudomonas aeruginosa, etc., P = 0.008). An indirect effects mediation model suggests that MIC accounted for approximately 13% (95% confidence interval, 3%–24%, P = 0.015) of the effect of the organism on 3-week visual acuity.
Moxifloxacin mediates the relationship between causative organisms and clinical outcome in bacterial keratitis, and is likely on the causal pathway between the organism and outcome. (ClinicalTrials.gov number, NCT00324168.)
Different etiologic organisms are thought to result in different clinical outcomes. Here, we found that moxifloxacin susceptibility mediates this relationship, suggesting it is on the causal pathway.
To analyze the minimum inhibitory concentration (MIC) of isolates from fungal keratitis to natamycin and voriconazole, and to assess the relationship between organism, MIC, and clinical outcome.
Data were collected as part of a randomized, controlled, double-masked clinical trial. Main outcome measures included best spectacle-corrected visual acuity (BSCVA), infiltrate/scar size, time to re-epithelialization, and perforation. Speciation and analysis of MIC to natamycin and voriconazole was done according to NCCLS standards. The relationship between MIC and organism, organism and outcome measure, and each outcome measure and MIC was assessed.
Of 120 samples obtained in the trial, 84 isolates had an identifiable organism and were available for further analyses. Fusarium spp and Aspergillus spp were the most commonly-isolated organisms. MIC was significantly different across the groups of organisms (P=0.0001). A higher MIC was significantly associated with an increased likelihood of perforation (OR 2.03, 95%CI 1.02 to 4.04, P=0.04). There was no significant association between MIC and 3-week visual acuity (0.058, 95%CI -0.01 to 0.13, P=0.11), 3-month visual acuity (0.01, 95%CI -0.08 to 1.04, P=0.79), 3-week infiltrate/scar size (0.12, 95% CI -0.02 to 0.27, P=0.10), 3-month infiltrate/scar size (0.12, 95%CI -0.02 to 0.25, P=0.09), or time to re-epithelialization (HR 1.19, 95%CI 0.98 to 1.45, P=0.08).
A higher MIC was associated with an increased odds of perforation. The results of this study suggest that resistance to antifungal medication may be associated with worse outcomes in fungal keratitis.
fungus; keratitis; susceptibility; voriconazole; natamycin
The role of antibiotic susceptibility testing on clinical outcome is unclear. In a randomized, controlled trial of bacterial keratitis, a higher minimum inhibitory concentration to moxifloxacin was significantly associated with worse visual acuity.
Background. For bacterial infections, the susceptibility to antibiotics in vitro has been associated with clinical outcomes in vivo, although the importance of minimum inhibitory concentration (MIC) has been debated. In this study, we analyzed the association of MIC on clinical outcomes in bacterial corneal ulcers, while controlling for organism and severity of disease at presentation.
Methods. Data were collected as part of a National Eye Institute–funded, randomized, controlled trial (the Steroids for Corneal Ulcers Trial [SCUT]). All cases enrolled in SCUT had a culture-positive bacterial corneal ulcer and received moxifloxacin. The MIC to moxifloxacin was measured by E test. Outcomes included best spectacle-corrected visual acuity, infiltrate/scar size, time to re-epithelialization, and corneal perforation.
Results. Five hundred patients with corneal ulcers were enrolled in the trial, and 480 were included in this analysis. The most commonly isolated organisms were Streptococcus pneumoniae and Pseudomonas aeruginosa. A 2-fold increase in MIC was associated with an approximately 0.02 logMAR decrease in visual acuity at 3 weeks, approximately 1 letter of vision loss on a Snellen chart (0.019 logMAR; 95% confidence interval [CI], .0040–.033; P = .01). A 2-fold increase in MIC was associated with an approximately 0.04-mm larger infiltrate/scar size at 3 weeks (0.036 mm; 95% CI, .010–.061; P = .006). After controlling for organism, a higher MIC was associated with slower time to re-epithelialization (hazards ratio, 0.92; 95% CI, .86–.97; P = .005).
Conclusions. In bacterial keratitis, a higher MIC to the treating antibiotic is significantly associated with worse clinical outcomes, with approximately 1 line of vision loss per 32-fold increase in MIC.
Clinical Trials Registration: NCT00324168.
Clinical isolates of Pseudomonas aeruginosa can be characterized as cytotoxic or invasive, based on their differing effects on host cells. Previous studies have shown that strain type influences pathology in animal models. The aim of this study was to determine if invasive and cytotoxic strains differentially impact clinical presentation, outcome, or therapeutic response in bacterial keratitis.
P.aeruginosa isolates from the NEI-funded Steroids for Corneal Ulcers Trial (SCUT) were subtyped as invasive or cytotoxic strains. The main outcome measure compared between the two subtypes was change in visual acuity at three months using Huber robust regression, adjusting for topical corticosteroid treatment.
Of the 101 confirmed P.aeruginosa isolates from the SCUT, 74 had a classically invasive or cytotoxic genotype. While corneal ulcers caused by genotypically invasive P.aeruginosa strains presented with significantly better visual acuity than those caused by genotypically cytotoxic P.aeruginosa strains when adjusting for the effect of ulcer location (p=0.008), invasive ulcers improved significantly less than cytotoxic ulcers at three months (0.35 logMAR (three and a half line difference), 95% CI 0.04 to 0.66 p=0.03). When compared with topical moxifloxacin alone, adjunctive treatment with topical corticosteroids was associated with significantly more improvement in visual acuity in the invasive subgroup (p=0.04), but was associated with less improvement in vision in the cytotoxic subgroup (p=0.07).
The results of this study suggest that rational profiling of differentially expressed virulence determinants, e.g. cytotoxicity and invasiveness for P.aeruginosa, could be used as a tool for decision making in management of infections to optimize outcome.
Pseudomonas aeruginosa; bacterial keratitis; virulence; type III secretion
Trachoma programs use mass distributions of oral azithromycin to treat the ocular strains of Chlamydia trachomatis that cause the disease. There is debate whether infection can be eradicated or only controlled. Mass antibiotic administrations clearly reduce the prevalence of chlamydia in endemic communities. However, perfect coverage is unattainable, and the World Health Organization's goal is to control infection to a level where resulting blindness is not a public health concern. Here, we use mathematical models to assess whether more ambitious goals such as local elimination or even global eradication are possible.
We fit a class of non-linear, stochastic, susceptible–infectious–susceptible (SIS) models which allow positive or negative feedback, to data from a recent community-randomized trial in Ethiopia, and make predictions using model averaging.
The models predict that reintroduced infection may not repopulate the community, or may do so sufficiently slowly that surveillance might be effective. The preferred model exhibits positive feedback, allowing a form of stochastic hysteresis in which infection returns slowly after mass treatment, if it returns at all. Results for regions of different endemicity suggest that elimination may be more feasible than earlier models had predicted.
If trachoma can be eradicated with repeated mass antibiotic distributions, it would encourage similar strategies against other bacterial diseases whose only host is humans and for which effective vaccines are not available.
Mathematical model; Stochastic model; Eradication; Chlamydia; Azithromycin; Quasi-stationary distribution; Backward bifurcation
Lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminths, and trachoma are the five most prevalent neglected tropical diseases in the world, and each is frequently treated with mass drug administrations. We performed a survey of neglected tropical diseases experts to elicit their opinions on the role of mass drug administrations for the elimination of these infections.
We sent an online survey to corresponding authors who had published an article about a neglected tropical disease from 2007 to 2011. Of 825 unique authors who were invited to complete the survey, 365 (44.2%) responded, including 234 (28.4%) who answered questions regarding one of the five most prevalent neglected tropical diseases. Respondents had varying opinions about the goals of programmatic activities for their chosen neglected tropical disease, with elimination or eradication identified as the most important goal by 87% of lymphatic filariasis respondents, 66% of onchocerciasis respondents, 55% of trachoma respondents, 24% of schistosomiasis respondents, and 21% of soil-transmitted helminth respondents. Mass drug administrations, other non-medication health measures, and education were generally thought to be more important for elimination than vector control, development of a new tool, or the presence of a secular trend. Drug resistance was thought to be a major limitation of mass drug administrations for all five neglected tropical diseases. Over half of respondents for lymphatic filariasis and trachoma thought that repeated mass drug administrations could eliminate infection within ten years of the initiation of mass treatments.
Respondents for lymphatic filariasis, onchocerciasis, and trachoma were more enthusiastic about the prospects of elimination and eradication than were respondents for schistosomiasis or soil-transmitted helminths. Mass drug administrations were generally believed to be among the most important factors for the success of elimination efforts for each of the five neglected tropical diseases, highlighting the opportunity for integrating drug distributions.
Mass drug administrations are used for each of the five most common neglected tropical diseases: lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminths, and trachoma. Three of these infections—lymphatic filariasis, onchocerciasis, and trachoma—are officially targeted for elimination, and mass drug administrations play a key role in the elimination plans for each. While progress has been demonstrated for each of these diseases, it is unclear whether researchers of these diseases think that elimination is feasible, or whether mass drug administrations should play an important role given the potential for drug resistance. We performed a survey of neglected tropical diseases experts to assess their opinions on the likelihood of elimination and the role of mass drug administrations for the five most common neglected tropical diseases. Most experts in lymphatic filariasis, onchocerciasis, and trachoma thought elimination was the appropriate goal of treatment programs, whereas most experts in schistosomiasis and soil-transmitted helminths thought that treatment programs were intended to control, but not eliminate, infection. Drug resistance was thought to be a major limitation for each of the infections. Although there were differences between the five infections, mass drug administrations, non-medication health measures, and education were generally thought to be the most important pieces of a control program.