Jaya D. Chidambaram

Comparison of Annual and Biannual Mass Antibiotic Administration for Elimination of Infectious Trachoma

CONTEXT Treatment recommendations assume that repeated mass antibiotic distributions can control, but not eradicate or even locally eliminate, the ocular strains of chlamydia that cause trachoma. Elimination may be an important end point because of concern that infection will return to communities that have lost immunity to chlamydia after antibiotics are discontinued. OBJECTIVE To determine whether biannual treatment can eliminate ocular chlamydial infection from preschool children and to compare results with the World Health Organization-recommended annual treatment. DESIGN, SETTING, AND PARTICIPANTS A cluster-randomized clinical trial of biannual vs annual mass azithromycin administrations to all residents of 16 rural villages in the Gurage Zone, Ethiopia, from March 2003 to April 2005. INTERVENTIONS At scheduled treatments, all individuals aged 1 year or older were offered a single dose of oral azithromycin either annually or biannually. MAIN OUTCOME MEASURE Village prevalence of ocular chlamydial infection and presence of elimination at 24 months in preschool children determined by polymerase chain reaction, correcting for baseline prevalence. Antibiotic treatments were performed after sample collections. RESULTS Overall, 14,897 of 16,403 eligible individuals (90.8%) received their scheduled treatment. In the villages in which residents were treated annually, the prevalence of infection in preschool children was reduced from a mean of 42.6% (range, 14.7%-56.4%) to 6.8% (range, 0.0%-22.0%) at 24 months. In the villages in which residents were treated biannually, infection was reduced from 31.6% pretreatment (range, 6.1%-48.6%) to 0.9% (range, 0.0%-4.8%) at 24 months. Biannual treatment was associated with a lower prevalence at 24 months (P = .03, adjusting for baseline prevalence). At 24 months, no infection could be identified in 6 of 8 of those treated biannually and in 1 of 8 of those treated annually (P = .049, adjusting for baseline prevalence). CONCLUSION Local elimination of ocular chlamydial infection appears feasible even in the most severely affected areas, although it may require biannual mass antibiotic distributions at a high coverage level. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00221364.

A rationale for continuing mass antibiotic distributions for trachoma.

BackgroundThe World Health Organization recommends periodic mass antibiotic distributions to reduce the ocular strains of chlamydia that cause trachoma, the worlds leading cause of infectious blindness. Their stated goal is to control infection, not to completely eliminate it. A single mass distribution can dramatically reduce the prevalence of infection. However, if infection is not eliminated in every individual in the community, it may gradually return back into the community, so often repeated treatments are necessary. Since public health groups are reluctant to distribute antibiotics indefinitely, we are still in need of a proven long-term rationale. Here we use mathematical models to demonstrate that repeated antibiotic distributions can eliminate infection in a reasonable time period.MethodsWe fit parameters of a stochastic epidemiological transmission model to data collected before and 6 months after a mass antibiotic distribution in a region of Ethiopia that is one of the most severely affected areas in the world. We validate the model by comparing our predicted results to Ethiopian data which was collected biannually for two years past the initial mass antibiotic distribution. We use the model to simulate the effect of different treatment programs in terms of local elimination of infection.ResultsSimulations show that the average prevalence of infection across all villages progressively decreases after each treatment, as long as the frequency and coverage of antibiotics are high enough. Infection can be eliminated in more villages with each round of treatment. However, in the communities where infection is not eliminated, it returns to the same average level, forming the same stationary distribution. This phenomenon is also seen in subsequent epidemiological data from Ethiopia. Simulations suggest that a biannual treatment plan implemented for 5 years will lead to elimination in 95% of all villages.ConclusionLocal elimination from a community is theoretically possible, even in the most severely infected communities. However, elimination from larger areas may require repeated biannual treatments and prevention of re-introduction from outside to treated areas.

Topical ocular antibiotics induce bacterial resistance at extraocular sites

Aim: To compare the prevalence of antibiotic resistance found in nasopharyngeal Streptococcus pneumoniae between villages treated with topical tetracycline or systemic azithromycin as part of a trachoma control programme. Methods: All children aged 1–10 years were offered either single dose oral azithromycin treatment (20 mg/kg) or a course of topical 1% tetracycline ointment, depending on the area. Treatment was given annually for 3 years. Six months after the third annual treatment in each village, children were surveyed for nasopharyngeal carriage of S pneumoniae and resistance was determined using broth dilution MIC technique. Children in two additional villages, which had not yet been treated, were also surveyed. Results: Nasopharyngeal carriage of S pneumoniae was similar in the tetracycline treated, azithromycin treated, and untreated areas (p = 0.57). However, resistance to tetracycline and azithromycin was distributed differently between the three areas (p = 0.004). The village treated with topical tetracycline had a higher prevalence of tetracycline resistance than the other villages (p = 0.010), while the oral azithromycin treated village had a higher prevalence of macrolide resistance than the other villages (p = 0.014). Conclusions: Annual mass treatment with oral azithromycin may alter the prevalence of drug resistant S pneumoniae in a community. Surprisingly, topical tetracycline may also increase nasopharyngeal pneumococcal resistance. Topical antibiotics may have an effect on extraocular bacterial resistance.

Prospective Comparison of Microbial Culture and Polymerase Chain Reaction in the Diagnosis of Corneal Ulcer

PURPOSE To compare polymerase chain reaction (PCR) to microbial culture for the detection and identification of bacterial and fungal pathogens in microbial keratitis. DESIGN Prospective cohort study. METHODS A total of 108 consecutive corneal ulcers were cultured and analyzed by PCR using pan-bacterial and pan-fungal primers. PCR products were cloned, sequenced, and compared to culture results using standard bioinformatics tools. RESULTS Of the 108 samples, 56 were culture-positive, 25 for bacteria and 31 for fungi; 52 were culture-negative. After eliminating false-positive PCR products, 94 of 108 were positive by PCR, 37 for bacteria and 57 for fungi. Nineteen of 25 bacterial culture-positive samples were positive by PCR, and 29 of 31 samples culture-positive for fungi were positive by PCR. The majority of sequenced PCR products matched the positive culture results. Of the 52 culture-negative samples, 46 (88%) yielded pathogen deoxyribonucleic acid (DNA) PCR products, 18 bacterial and 28 fungal. These represented a variety of species, including at least three novel previously uncultured microbes. CONCLUSIONS PCR detects microbial DNA in the majority of bacterial and fungal corneal ulcers, and identifies potentially pathogenic organisms in a high proportion of culture-negative cases. Yield and concordance with culture are higher for fungal than bacterial ulcers. Practical use of the technique is limited by artefactual amplification of nonpathogenic organisms. PCR may be used as an adjunct to culture to identify potential pathogens in microbial keratitis.

Corticosteroids for bacterial corneal ulcers.

Aims: The aim of the study was to conduct a preliminary clinical trial to assess whether adjunctive topical corticosteroids improve outcomes in bacterial keratitis and, if no difference was found, to determine the feasibility and sample size necessary for conducting a larger trial to answer this question. Methods: In this single centre, double-masked clinical trial, 42 patients with culture-confirmed bacterial keratitis at Aravind Eye Hospital in India were randomised to receive either topical prednisolone phosphate or placebo. All patients received topical moxifloxacin. The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months, adjusting for enrolment BSCVA and arm. Other pre-specified outcomes included re-epithelialisation time, infiltrate/scar size and adverse events. Results: Compared with placebo, patients in the steroid group re-epithelialised more slowly (hazard ratio 0.47, 95% CI 0.23 to 0.94). There was no significant difference in BSCVA or infiltrate/scar size at 3 weeks or 3 months. To have 80% power to detect a two-line difference in acuity, 360 cases would be required. Conclusions: Although corticosteroid treatment resulted in a statistically significant delay in re-epithelialisation, this did not translate to a significant difference in visual acuity, infiltrate/scar size or adverse events. To assess the effect of steroids on acuity, a larger trial is warranted and feasible. Trial registration number: NCT00324168

Pesky trachoma suspect finally caught

Aim: Face seeking flies have long been thought to transmit Chlamydia trachomatis, the causative agent of trachoma, but this has never been proven. The four criteria proposed by Barnett, previously used to incriminate other arthropods suspected of transmitting disease, were examined. One of these criteria remains unmet: the repeated demonstration of the presence of C trachomatis on flies. The authors used polymerase chain reaction (PCR) to look for the presence of C trachomatis DNA on flies in the Gurage Zone of Ethiopia. Methods: Using sticky paper, one fly was collected from the face of each of 103 children aged 1–10 years. The piece of fly paper to which the fly was attached was cut out, followed by the collection of an empty piece from an arbitrary area of the fly paper, which served as control. Roche Amplicor PCR kits were used to detect C trachomatis DNA. Results: Evidence of C trachomatis by PCR was found on 15 of 103 flies versus 0 of 103 controls (p = 0.0001). Conclusion: These results meet the final criterion needed to incriminate flies as a vector of trachoma. However, interventional studies will be needed to show the importance of fly control.

Trachoma Decline and Widespread Use of Antimicrobial Drugs

Widespread use of antimicrobial drugs may be contributing to trachoma decline.

Susceptibility testing and clinical outcome in fungal keratitis

Fungal keratitis causes significant morbidity, especially in tropical climates, and is notoriously difficult to manage. The choice of antifungal agent for fungal keratitis remains largely empirical, with no consensus on the role of susceptibility testing in guiding therapy. Studies suggest that susceptibility and outcome may be associated in systemic fungal infections with some dimorphic fungi,1 but this correlation may not exist for filamentous fungi or in ocular disease because of frequent topical dosing and high drug concentration. Given the availability of new topical medications, tailoring antifungal therapy based on microbial sensitivity is important.2 Here, we assess whether fungal susceptibility testing correlates with clinical outcomes in cases of fungal keratitis. This study was a retrospective case review of consecutive patients with culture proven fungal keratitis presenting to the Aravind Eye Hospital cornea clinic between March and July 2004. Of 98 consecutive patients, minimum inhibitory concentration (MIC) data was available for 90.3 Eighty-one corresponding charts were available, and 54 charts had follow-up of at least 3 weeks to allow determination of healing. All cases were …

Association of Conjunctival Bacterial Infection and Female Sex in Cicatricial Trachoma

PURPOSE Conjunctival infection with non-chlamydial bacteria may play an important role in the progression of trachoma, especially with regard to the development of corneal opacity and blindness. To further characterize the microbiological profile of bacterial conjunctival infections in cicatricial trachoma, a conjunctival swabbing of adults in rural Ethiopia was performed. METHODS In a cross-sectional study conducted in nine Ethiopian villages with hyperendemic trachoma, persons 40 years of age or older with signs or symptoms consistent with trichiasis were recruited and conjunctival swabbing for bacterial pathogens was performed. RESULTS Conjunctival examination and swabbing on 112 females and 36 males were performed. Of the 148 study participants, 101 (68.2%) were confirmed to have trichiasis, and 118 (80%) had conjunctival swabs positive for bacteria. In multivariate analyses, growth of pathogenic conjunctival bacteria was independently associated with trichiasis (odds ratio [OR] 6.93; 95% confidence interval [CI] 2.71-17.7) and female sex (OR 5.90; 95% CI 2.09-16.7). Females were more likely to have swabs positive for Streptococcus pneumoniae or Haemophilus influenzae than were males (OR 9.09; 95% CI 1.17-70.8). CONCLUSIONS In a region of Ethiopia with endemic trachoma, conjunctival bacterial growth was more common in females than that in males. S. pneumoniae and H. influenzae, both of which frequently colonize the nasopharynx of children, were more common in females, suggesting that the preponderance of infection in females may be attributable to close contact with children. This finding is consistent with the theory that childcare activities may preferentially expose females to ocular chlamydial infection. (ClinicalTrials.gov number, NCT00221364.).

The order is rapidly fadin

Onchocerciasis and trachoma may become historical diseases within our lifetime In this issue of the BJO (p 796), Egbert et al utilise a case-control design to demonstrate that onchocerciasis and glaucoma are associated in an area of Ghana. Perhaps this is not surprising, as onchocerciasis is known to cause anterior segment inflammation and peripheral anterior synechiae, which can in turn lead to increased intraocular pressure. However, this association had never really been proved in the past, in part because reliable glaucoma data in the developing world have been difficult to come by. Interestingly, as glaucoma has become more recognised, onchocerciasis has become less so—glaucoma has moved up to number two in the WHO’s latest rankings, while onchocerciasis may have made the list for the last time at number 8 (table 1).1 This may be the ideal time to make such an association between these two diseases when awareness of both diseases is relatively …