Alterations in the conjunctival bacterial flora following a single dose of azithromycin in a trachoma endemic area

β-Lactam-Resistant Streptococcus pneumoniae Dynamics Following Treatment: A Dose-Response Meta-analysis

BACKGROUND

Patient exposure to antibiotics promotes the emergence of drug-resistant pathogens. The aim of this study was to identify whether the temporal dynamics of resistance emergence at the individual-patient level were predictable for specific pathogen-drug classes.

METHODS

Following a systematic review, a novel robust error meta-regression method for dose-response meta-analysis was used to estimate the odds ratio (OR) for carrying resistant bacteria during and following treatment compared to baseline. Probability density functions fitted to the resulting dose-response curves were then used to optimize the period during and/or after treatment when resistant pathogens were most likely to be identified.

RESULTS

Studies of Streptococcus pneumoniae treatment with β-lactam antibiotics demonstrated a peak in resistance prevalence among patients 4 days after completing treatment with a 3.32-fold increase in odds (95% confidence interval [CI], 1.71-6.46). Resistance waned more gradually than it emerged, returning to preexposure levels 1 month after treatment (OR, 0.98 [95% CI, .55-1.75]). Patient isolation during the peak dose-response period would be expected to reduce the risk that a transmitted pathogen is resistant equivalently to a 50% longer isolation window timed from the first day of treatment.

CONCLUSIONS

Predictable temporal dynamics of resistance levels have implications both for surveillance and control.

Effect of Azithromycin on the Ocular Surface Microbiome of Children in a High Prevalence Trachoma Area

PURPOSE

The aim of this study was to evaluate the effect of the 4 times per year mass azithromycin distributions on the ocular surface microbiome of children in a trachoma endemic area.

METHODS

In this cluster-randomized controlled trial, children aged 1 to 10 years in rural communities in the Goncha Seso Enesie district of Ethiopia were randomized to either no treatment or treatment with a single dose of oral azithromycin (height-based dosing to approximate 20 mg/kg) every 3 months for 1 year. Post hoc analysis of ocular surface Chlamydia trachomatis load, microbial community diversity, and macrolide resistance determinants was performed to evaluate differences between treatment arms.

RESULTS

One thousand two hundred fifty-five children from 24 communities were included in the study. The mean azithromycin coverage in the treated communities was 80% (95% CI: 73%-86%). The average age was 5 years (95% CI: 4-5). Ocular surface C. trachomatis load was reduced in children treated with the 4 times per year azithromycin ( P = 0.0003). Neisseria gonorrhoeae , Neisseria lactamica , and Neisseria meningitidis were more abundant in the no-treatment arm compared with the treated arm. The macrolide resistance gene ermB was not different between arms ( P = 0.63), but mefA / E was increased ( P = 0.04) in the azithromycin-treated arm.

CONCLUSIONS

We found a reduction in the load of C. trachomatis and 3 Neisseria species in communities treated with azithromycin. These benefits came at the cost of selection for macrolide resistance.

In Vitro and In Vivo Activity of (Trifluoromethyl)pyridines as Anti-Chlamydia trachomatis Agents

Chlamydia trachomatis is the leading pathogen in sexually transmitted bacterial infections across the globe. The development of a selective treatment against this pathogen could be an attractive therapeutic option that will reduce the overuse of broad-spectrum antibiotics. Previously, we reported some sulfonylpyridine-based compounds that showed selectivity against C. trachomatis. Here, we describe a set of related compounds that display enhanced anti-chlamydial potency when compared to our early leads. We found that the active molecules are bactericidal and have no impact on Staphylococcus aureus or Escherichia coli strains. Importantly, the molecules were not toxic to mammalian cells. Furthermore, a combination of molecule 20 (the most active molecule) and azithromycin at subinhibitory concentrations acted synergistically to inhibit chlamydial growth. Molecule 20 also eradicated Chlamydia in a 3D infection model and accelerated the recovery of Chlamydia-infected mice. This work presents compounds that could be further developed to be used alone or in combination with existing treatment regimens against chlamydial infections.

Metagenomics in ophthalmology: current findings and future prospectives

Less than 1% of all microorganisms of the available environmental microbiota can be cultured with the currently available techniques. Metagenomics is a new methodology of high-throughput DNA sequencing, able to provide taxonomic and functional profiles of microbial communities without the necessity to culture microbes in the laboratory. Metagenomics opens to a ‘hypothesis-free’ approach, giving important details for future research and treatment of ocular diseases in ophthalmology, such as ocular infection and ocular surface diseases.

Composition and Comparison of the Ocular Surface Microbiome in Infants and Older Children

Purpose

Unlike other microbiomes of the body, the composition of the ocular surface microbiome (OSM) in children has yet to be thoroughly explored. Our goal was to evaluate the OSM in young infants and compare its composition to older children using both culture dependent and independent methodologies to assess for differences with age.

Methods

Prospective, observational, cross-sectional study of children <18 years of age at a university-based institution. The mucosal surfaces of both eyes, nose and throat were swabbed with a forensic-quality swab. Half of the swab was plated for culture and the other half underwent 16S sequencing. Culture results and microbiome diversity were analyzed.

Results

Fifty patients (mean age 37 months, range 1-168 months) were enrolled. Forty-seven eyes of 30 patients had positive cultures; four eyes grew >1 species. Culture positive patients were older (43 vs. 29 months, P = 0.19). Additionally, older children had greater diversity than children under 6 months of age by 16S sequencing (P = 0.05). Staphylococcus species were predominant by culture (35/52 isolates) and by 16S sequencing. The OSM was fairly similar to the nose microbiome, whereas the throat microbiome differed significantly and had a higher abundance of Streptococcaceae (P = 0.001).

Conclusions

The OSM is predominantly composed of Staphylococcus species in children, as demonstrated by both culture dependent and culture independent methods. Older children were more likely to have growth on culture and have more a complex bacterial milieu with 16S sequencing.

Translational Relevance

16S sequencing provides more robust information regarding the composition of the microbiomes than culture dependent methods.

Resistance decay in individuals after antibiotic exposure in primary care: a systematic review and meta-analysis

BACKGROUND

Antibiotic resistance is an urgent global problem, but reversibility is poorly understood. We examined the development and decay of bacterial resistance in community patients after antibiotic use.

METHODS

This was a systematic review and meta-analysis. PubMed, EMBASE and CENTRAL (from inception to May 2017) were searched, with forward and backward citation searches of the identified studies. We contacted authors whose data were unclear, and of abstract-only reports, for further information. We considered controlled or times-series studies of patients in the community who were given antibiotics and where the subsequent prevalence of resistant bacteria was measured. Two authors extracted risk of bias and data. The meta-analysis used a fixed-effects model.

RESULTS

Of 24,492 articles screened, five controlled and 20 time-series studies (total 16,353 children and 1461 adults) were eligible. Resistance in Streptococcus pneumoniae initially increased fourfold after penicillin-class antibiotic exposure [odds ratio (OR) 4.2, 95% confidence interval (CI) 3.5-5.4], but this fell after 1 month (OR 1.7, 95% CI 1.3-2.1). After cephalosporin-class antibiotics, resistance increased (OR 2.2, 95%CI 1.7-2.9); and fell to (OR 1.6, 95% CI 1.2-2.3) at 1 month. After macrolide-class antibiotics, resistance increased (OR 3.8, 95% CI 1.9-7.6) and persisted for 1 month (OR 5.2, 95% CI 2.6-10.3) and 3 months (OR 8.1, 95% CI 4.6-14.2, from controlled studies and OR 2.3, 95% CI 0.6-9.4, from time-series studies). Resistance in Haemophilus influenzae after penicillins was not significantly increased (OR 1.3, 95% CI 0.9-1.9) initially but was at 1 month (OR 3.4, 95% CI 1.5-7.6), falling after 3 months (OR 1.0, 95% CI 0.5-2.2). Data were sparse for cephalosporins and macrolides. Resistance in Enterobacter increased post-exposure (OR 3.2, 95% CI 0.9-10.8, from controlled studies and OR 7.1, 95% CI 4.2-12, from time-series studies], but was lower after 1 month (OR 1.8, 95% CI 0.9-3.6).

CONCLUSIONS

Resistance generally increased soon after antibiotic use. For some antibiotic classes and bacteria, it partially diminished after 1 and 3 months, but longer-term data are lacking and urgently needed.

TRIAL REGISTRATION

PROSPERO CRD42015025499 .

Effect of clinical parameters on the ocular surface microbiome in children and adults

Purpose

To perform a pilot study to characterize the effect of clinical parameters on the ocular surface microbiome (OSM) in children and adults using 16s ribosomal RNA sequencing.

Methods

Prospective, cross-sectional study using 16s sequencing to evaluate the OSM. Comparisons were made in bacterial composition by 1) age, 2) gender, 3) sampling location of the ocular and periocular surfaces, and 4) topical drop use. 16s sequencing was performed using Illumina MiSeq 250 and analyzed using Qiime.

Results

Thirty patients (15 children [mean 3.7 years], 15 adults [mean 60.4 years]) were sampled. Both principal coordinate analysis and unifrac distance analysis showed significant differences in the composition between the pediatric and adult OSMs (both p=0.001). The eyelid margin microbiota did not show any distinct clustering compared to conjunctiva within the pediatric samples but tended to show a distinction between anatomic sites in adult samples. No differences in OSM were noted by topical drop use.

Conclusion

16s sequencing is a useful tool in evaluating the OSM in patients of all ages, showing a distinct difference between pediatric and adult microbiomes.

Trachomatous Scarring and Infection With Non-Chlamydia Trachomatis Bacteria in Women in Kongwa, Tanzania

Purpose

To assess for an association between conjunctival infection with nonchlamydial bacterial species and the presence of trachomatous scarring (TS) in women in central Tanzania.

Methods

Cross-sectional data were collected from a random sample of women ages 18 and older in 47 trachoma-endemic communities in Kongwa, Tanzania. Each participant completed a survey, provided a conjunctival swab sample, and received an ocular exam to assess for TS. Biologic samples were cultured for bacterial growth and speciation. Contingency tables were used to assess the associations between TS and bacterial carriage.

Results

Complete data was provided by 3882 women (80.7% of invitees). Of all samples, 14% resulted in a positive bacterial isolate. There was no association between TS and nonchlamydial bacterial carriage, whether assessed by species, pathogenicity, or in aggregate. There was a significant association between increasing age and TS severity, but not between age and bacterial carriage. No Corynebacterium was found in the swabs.

Conclusions

This study found no association between TS and nonchlamydial ocular infections, although associations with Corynebacterium cannot be ruled out.

Azithromycin, fluoroquinolone and chloramphenicol resistance of non-chlamydia conjunctival bacteria in rural community of Ethiopia

Aim:

To determine profiles of non-chlamydia conjunctival bacteria and their antimicrobial susceptibility from adults who underwent trachomatous trichiasis surgery in rural areas of Ethiopia.

Materials and Methods:

A cross-sectional study was conducted in rural districts in West Gojjam administrative zone. Conjunctival swabs were collected during surgery and transported using Stuart transport broth (Oxoid, UK). Antibiotic susceptibility of conjunctival isolates was determined using the Kirby-Bauer disc-diffusion method.

Results:

Non-chlamydia pathogenic bacteria were recovered from conjunctiva of 438 (31%) participants before treatment. The isolated conjunctival bacteria were Staphylococcus aureus, coagulase-negative Staphylococci, Streptococcus group (A, C, F and G), Enterococci, Streptococcus pneumoniae, Moraxella spp., Escherichia coli, Citrobacter spp., Proteus spp., Klebsiella spp., Pseudomonas spp. and Enterobacter spp. Overall, resistance rates of 57.8% to azithromycin and 68.5% to chloramphenicol were found. However, 86-94.4% sensitivity was demonstrated to ciprofloxacin and norfloxacin. Moderate sensitivity rates (61.8-78.4%) were observed to ceftriaxone, tetracycline and cotrimoxazole.

Conclusion:

Fluoroquinolones that have activity against the majority of bacterial isolates were potent at in vitro. However, unacceptably high levels of resistance to azithromycin and chloramphenicol in rural community indicated a need for further study and antimicrobial resistance surveillance.

When does overuse of antibiotics become a tragedy of the commons?

BACKGROUND

Over-prescribing of antibiotics is considered to result in increased morbidity and mortality from drug-resistant organisms. A resulting common wisdom is that it would be better for society if physicians would restrain their prescription of antibiotics. In this view, self-interest and societal interest are at odds, making antibiotic use a classic "tragedy of the commons".

METHODS AND FINDINGS

We developed two mathematical models of transmission of antibiotic resistance, featuring de novo development of resistance and transmission of resistant organisms. We analyzed the decision to prescribe antibiotics as a mathematical game, by analyzing individual incentives and community outcomes.

CONCLUSIONS

A conflict of interest may indeed result, though not in all cases. Increased use of antibiotics by individuals benefits society under certain circumstances, despite the amplification of drug-resistant strains or organisms. In situations where increased use of antibiotics leads to less favorable outcomes for society, antibiotics may be harmful for the individual as well. For other scenarios, where a conflict between self-interest and society exists, restricting antibody use would benefit society. Thus, a case-by-case assessment of appropriate use of antibiotics may be warranted.

What is causing active trachoma? The role of nonchlamydial bacterial pathogens in a low prevalence setting

PURPOSE

In low prevalence settings, clinically active follicular trachoma (TF) is often found in the absence of detectable Chlamydia trachomatis. The reasons for this persistent follicular phenotype are not well understood; one possible explanation is that other bacterial species are provoking the inflammatory response. This study investigated the relationship between TF, C. trachomatis, and nonchlamydial bacterial infection.

METHODS

A cross-sectional survey was conducted in a trachoma endemic village in Tanzania. All available children were examined for trachoma and swabs were collected for microbiologic culture (blood and chocolate agar) and C. trachomatis PCR (Amplicor).

RESULTS

Four hundred seventy-three children under 10 years of age were recruited for this study. The prevalences of TF and C. trachomatis were 13.7% and 5.3%, respectively, and were not associated. Bacteria were cultured from 305 (64.5%) swab samples; 162 (34.3%) grew a pathogen (with or without a commensal organism) and 143 (30.2%) grew commensal bacteria only. The most common pathogens were Streptococcus pneumoniae and Haemophilus influenzae (type B and non-type B). The presence of bacterial pathogens was associated with TF (odds ratio, 4.68; 95% confidence interval, 2.31-9.50; P < 0.001).

CONCLUSIONS

In regions with low levels of endemic trachoma, it is possible that much of the TF that is observed is attributable to nonchlamydial bacterial pathogens. It is plausible that individuals who have previously developed a follicular conjunctivitis in response to C. trachomatis may more readily reform conjunctival follicles when challenged with certain other bacterial species.

Diversity of bacteria at healthy human conjunctiva

PURPOSE

Ocular surface (OS) microbiota contributes to infectious and autoimmune diseases of the eye. Comprehensive analysis of microbial diversity at the OS has been impossible because of the limitations of conventional cultivation techniques. This pilot study aimed to explore true diversity of human OS microbiota using DNA sequencing-based detection and identification of bacteria.

METHODS

Composition of the bacterial community was characterized using deep sequencing of the 16S rRNA gene amplicon libraries generated from total conjunctival swab DNA. The DNA sequences were classified and the diversity parameters measured using bioinformatics software ESPRIT and MOTHUR and tools available through the Ribosomal Database Project-II (RDP-II).

RESULTS

Deep sequencing of conjunctival rDNA from four subjects yielded a total of 115,003 quality DNA reads, corresponding to 221 species-level phylotypes per subject. The combined bacterial community classified into 5 phyla and 59 distinct genera. However, 31% of all DNA reads belonged to unclassified or novel bacteria. The intersubject variability of individual OS microbiomes was very significant. Regardless, 12 genera-Pseudomonas, Propionibacterium, Bradyrhizobium, Corynebacterium, Acinetobacter, Brevundimonas, Staphylococci, Aquabacterium, Sphingomonas, Streptococcus, Streptophyta, and Methylobacterium-were ubiquitous among the analyzed cohort and represented the putative "core" of conjunctival microbiota. The other 47 genera accounted for <4% of the classified portion of this microbiome. Unexpectedly, healthy conjunctiva contained many genera that are commonly identified as ocular surface pathogens.

CONCLUSIONS

The first DNA sequencing-based survey of bacterial population at the conjunctiva have revealed an unexpectedly diverse microbial community. All analyzed samples contained ubiquitous (core) genera that included commensal, environmental, and opportunistic pathogenic bacteria.

Efficacy and safety of short-duration topical treatment with azithromycin oil-based eyedrops in an experimental model of corneal refractive surgery

PURPOSE

To assess the tolerance and side effects of azithromycin eyedrops at the ocular surface after corneal refractive surgery in an experimental animal model.

METHODS

The effect of azithromycin eyedrops was evaluated in hen corneas that underwent laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) surgery in 1 eye, using the fellow eye (not manipulated) as a control. Animals were treated bid 3 days prior to surgery and 3 days after surgery with T1225 1.5% azithromycin eyedrops or saline eyedrops (balanced salt solution), or were left untreated as a control. Clinical course and cell biology (apoptosis, proliferation, and differentiation) measurements were assessed.

RESULTS

Infections were present in the following proportions of corneas operated on by LASIK: 0% treated with azithromycin, 60% treated with BSS, and 30% untreated. No corneal abscess or keratitis were present in any PRK or unmanipulated corneas. Conjunctival edema and redness were less prevalent in LASIK-operated eyes treated with azithromycin than in BSS-treated or untreated eyes and were not observed in any PRK or unmanipulated corneas. In PRK-operated eyes treated with azithromycin, a decrease was observed in the apoptosis and an increase in the stromal proliferation. There were no differences in these parameters for LASIK and unmanipulated eyes.

CONCLUSIONS

Topical administration of T1225 oil-based azithromycin eyedrops was well tolerated in both unmanipulated hen corneas and those treated with corneal refractive surgery (PRK and LASIK). T1225 demonstrated a potent antibiotic effect after LASIK treatment.

Epidemiology and control of trachoma: systematic review

Trachoma is the commonest infectious cause of blindness. Recurrent episodes of infection with serovars A-C of Chlamydia trachomatis cause conjunctival inflammation in children who go on to develop scarring and blindness as adults. It was estimated that in 2002 at least 1.3 million people were blind from trachoma, and currently 40 million people are thought to have active disease and 8.2 million to have trichiasis. The disease is largely found in poor, rural communities in developing countries, particularly in sub-Saharan Africa. The WHO promotes trachoma control through a multifaceted approach involving surgery, mass antibiotic distribution, encouraging facial cleanliness and environmental improvements. This has been associated with significant reductions in the prevalence of active disease over the past 20 years, but there remain a large number of people with trichiasis who are at risk of blindness.

Strategies to control trachoma

Trachoma is a significant public health problem that is endemic in 57 countries, affecting 40.6 million people and contributing to 4% of the global burden of blindness. Repeated episodes of infection from Chlamydia trachomatis lead to long-term inflammation, scarring of the tarsal conjunctiva and distortion of the upper eyelid with in-turning of eyelashes that abrade the surface of the globe. This constant abrasion, in turn, can cause irreversible corneal opacity and blindness. The Alliance for the Global Elimination of Trachoma by 2020 (GET2020) has adopted the SAFE (Surgery, Antibiotics, Facial cleanliness and Environmental improvement) strategy as the main action against trachoma. Trichiasis surgery reduces the risk of blindness by reversing the in-turning of eyelashes and also improves the quality of life from non-visual symptoms. However, future efforts need to aim at increasing accessibility to surgery and improving acceptance. Antibacterials are required to reduce the burden of infection. Oral azithromycin is as close to the perfect antibacterial as we will get for mass distribution: it is safe, requires only a single oral dose, treatment is usually repeated every 6-12 months, resistance is not seen as a problem, and cost is not a limiting factor with a large donation programme and newer generic versions of the drug. Future focus should be on the details of antibacterial distribution such as coverage, frequency of distribution and target population. The promotion of facial cleanliness through education may be the key to trachoma elimination as it will stop the frequent exchange of infected ocular secretions and thus reduce the transmission of infection. However, innovative methods are required to translate health education and promotion activities into sustainable changes in hygiene behaviour. Environmental improvements should focus on the barriers to achieving facial cleanliness and cost-effective means need to be identified. There are a number of countries already eligible for certification of trachoma elimination and if current momentum continues, blinding trachoma can be eliminated by the year 2020.

Azithromycin-chloroquine and the intermittent preventive treatment of malaria in pregnancy

In the high malaria-transmission settings of sub-Saharan Africa, malaria in pregnancy is an important cause of maternal, perinatal and neonatal morbidity. Intermittent preventive treatment of malaria in pregnancy (IPTp) with sulphadoxine-pyrimethamine (SP) reduces the incidence of low birth-weight, pre-term delivery, intrauterine growth-retardation and maternal anaemia. However, the public health benefits of IPTp are declining due to SP resistance. The combination of azithromycin and chloroquine is a potential alternative to SP for IPTp. This review summarizes key in vitro and in vivo evidence of azithromycin and chloroquine activity against Plasmodium falciparum and Plasmodium vivax, as well as the anticipated secondary benefits that may result from their combined use in IPTp, including the cure and prevention of many sexually transmitted diseases. Drug costs and the necessity for external financing are discussed along with a range of issues related to drug resistance and surveillance. Several scientific and programmatic questions of interest to policymakers and programme managers are also presented that would need to be addressed before azithromycin-chloroquine could be adopted for use in IPTp.

Trachoma

Trachoma is a keratoconjunctivitis caused by ocular infection with Chlamydia trachomatis. Repeated or persistent episodes lead to increasingly severe inflammation that can progress to scarring of the upper tarsal conjunctiva. Trichiasis develops when scarring distorts the upper eyelid sufficiently to cause one or more lashes to abrade the cornea, scarring it in turn and causing blindness. Active trachoma affects an estimated 84 million people; another 7.6 million have end-stage disease, of which about 1.3 million are blind. Trachoma should stand on the brink of extinction thanks to a 1998 initiative launched by WHO--the Global Elimination of Trachoma by 2020. This programme advocates control of trachoma at the community level with four inter-related population-health initiatives that form the SAFE strategy: surgery for trichiasis, antibiotics for active trachoma, facial cleanliness, and environmental improvement. Evidence supports the effectiveness of this approach, and if current world efforts continue, blinding trachoma will indeed be eliminated by 2020.

Ocular pharmacokinetic study following single and multiple azithromycin administrations in pigmented rabbits

PURPOSE

The aim of this study was to investigate whether the ocular pharmacokinetic parameters observed following systemic administration are also seen following topical administration.

METHODS

Azithromycin concentrations were measured by HPLC-MS in pigmented rabbits' tears, cornea, bulbar conjunctiva, and aqueous humor following single instillation and twice-daily instillations for three consecutive days of topical 1.50% azithromycin dihydrate solution.

RESULTS

Following a single administration, azithromycin levels were higher than the MIC 4 microg/g breakpoint for susceptible germs for at least 4 hr in tears, 1 hr in conjunctiva, and 1 hr in cornea after instillation. Following multiple administrations, azithromycin levels were higher than the MIC 4 microg/g for at least 16 hr in tears, 24 hr in conjunctivae, and 1 week in cornea after the last instillation.

CONCLUSIONS

Both dosage regimens resulted in adequate and long-lasting azithromycin levels in the conjunctiva, the ocular target tissue relative to the expected therapeutic indication in man (bacterial conjunctivitis), and also in the cornea and tears.

The pharmacodynamic properties of azithromycin in a kinetics-of-kill model and implications for bacterial conjunctivitis treatment

INTRODUCTION

Antibiotics have traditionally been classified as bactericidal or bacteriostatic. Azithromycin belongs to the parent class of macrolides that are characteristically bacteriostatic. Some evidence suggests that this molecule demonstrates bactericidal kill and has concentration-dependent effects. This study tests the hypothesis that azithromycin demonstrates a bactericidal, concentration-dependent antibiotic effect at concentrations corresponding to and exceeding published tear and conjunctival levels.

METHODS

The antibacterial activity of different concentrations of azithromycin 1% in DuraSite(R) (AzaSite(R); Inspire Pharmaceuticals Inc, Durham, NC, USA) was evaluated using a kinetics-of-kill model. Recent conjunctivitis isolates of Staphylococcus aureus, Streptococcus pneumoniae or Haemophilus influenzae were exposed to four concentrations of azithromycin (100, 250, 500 and 750 microg/ml). Starting concentrations were similar to the maximum concentrations (Cmax) that have been demonstrated in conjunctiva (83 microg/g) and tears (288 microg/ml) following topical ocular administration. The percentage of surviving bacteria at 30 and 60 minutes following exposure to each concentration were determined.

RESULTS

Azithromycin failed to demonstrate bactericidal activity (i.e. a 3-log reduction in surviving bacteria) against S. aureus, S. pneumoniae or H. influenzae. Furthermore, the rate and extent of antibacterial activity with azithromycin did not change with higher concentrations, even at the highest tested concentration of 750 microg/ml.

CONCLUSION

Similar to the parent macrolide class, azithromycin demonstrates bacteriostatic activity against common conjunctival pathogens up to the maximum tested concentration of 750 microg/ml (i.e. 2.6-times and 9-times published Cmax tear and conjunctival concentration, respectively). Azithromycin's bacteriostatic effects and prolonged elimination half-life will likely lead to a corresponding increase in the emergence of macrolide-resistant isolates.

Comparison of azithromycin and moxifloxacin against bacterial isolates causing conjunctivitis

OBJECTIVE

To examine in vitro resistance to azithromycin and moxifloxacin in bacterial conjunctivitis isolates.

METHODS

MIC90s (Minimum Inhibitory Concentration) and resistance rates to azithromycin and moxifloxacin were determined based upon microtiter broth dilution and/or antimicrobial gradient test strips in a multicenter phase III study and confirmed externally.

RESULTS

The most common isolates collected from bacterial conjunctivitis patients in the phase III study were Haemophilus influenzae (40.6%), followed by Staphylococcus epidermidis (19.3%), Propionibacterium acnes (17.3%), Streptococcus pneumoniae (16.8%), and Staphylococcus aureus (0.06%). MIC90s for all of these organisms were well below established resistance breakpoints for moxifloxacin, indicating no bacterial resistance. On the other hand, the MIC90 for H. influenzae was 3-fold higher than the resistance breakpoint for azithromycin, > or = 128-fold higher for S. epidermidis, 16-fold higher for S. pneumoniae and > or = 128-fold higher for S. aureus, indicating moderate to very high bacterial resistance to azithromycin.

CONCLUSIONS

Resistance to azithromycin is more common than resistance to moxifloxacin in clinical isolates causing bacterial conjunctivitis.

Efficacy and safety of short duration azithromycin eye drops versus azithromycin single oral dose for the treatment of trachoma in children: a randomised, controlled, double-masked clinical trial

AIMS

Efficacy and safety of a short-duration treatment of azithromycin 1.5% eye drops versus oral azithromycin to treat active trachoma.

METHODS

Randomised, controlled, double-masked, double-dummy, non-inferiority explanatory study including 670 children from Guinea Conakry and Pakistan if: 1-10 years old; active trachoma (TF+TI0 or TF+TI+ on simplified World Health Organisation (WHO) scale). Three groups received either: azithromycin 1.5% eye drops twice daily for 2 days, for 3 days or azithromycin single 20 mg/kg oral dose. Patients' contacts were treated whenever possible. Clinical evaluation was performed using a binocular loupe. Primary efficacy variable was the cure (no active trachoma (TF0)) at day 60. Non-inferiority margin for difference between cure rates was 10%.

RESULTS

Cure rate in per protocol set was as follows: 93.0%, 96.3% and 96.6% in 2-day group 3-day group, and oral treatment group, respectively. Azithromycin 1.5% groups were non-inferior to oral azithromycin. The intend to treat (ITT) analysis supported the results. Clinical re-emergence rate was low: 4.2%. Ocular tolerance was similar for all groups. No treatment related adverse events were reported. Logistic regression analyses found prognostic factors such as: country (p<0.001) and trachoma severity (p = 0.003).

CONCLUSIONS

In active trachoma, azithromycin eye drops twice daily for 2 or 3 days are as efficient as the WHO's reference treatment and represent an innovative alternative to oral azithromycin.

A randomised controlled trial of azithromycin following surgery for trachomatous trichiasis in the Gambia

BACKGROUND/AIM

Trachomatous trichiasis frequently returns following surgery. Several factors may promote recurrence: preoperative disease severity, surgeon ability, surgical procedure, healing responses, and infection. This study investigates whether enhanced control of infection, both of Chlamydia trachomatis and other bacteria, with azithromycin can improve surgical outcome in a trachoma control programme.

METHODS

Individuals with trachomatous trichiasis were examined and operated. After surgery patients were randomised to the azithromycin or control group. The azithromycin group and children in their household were given a dose of azithromycin. Antibiotic treatment was repeated at 6 months. All patients were reassessed at 6 months and 12 months. Samples were collected for C trachomatis polymerase chain reaction and general microbiology at each examination.

RESULTS

451 patients were enrolled. 426 (94%) were reassessed at 1 year, of whom 176 (41.3%) had one or more lashes touching the eye and 84 (19.7%) had five or more lashes. There was no difference in trichiasis recurrence between the azithromycin and control group. Recurrent trichiasis was significantly associated with more severe preoperative trichiasis, bacterial infection, and severe conjunctival inflammation at 12 months. Significant variability in outcome was found between surgeons. Visual acuity and symptoms significantly improved following surgery.

CONCLUSION

In this setting, with a low prevalence of active trachoma, azithromycin did not improve the outcome of trichiasis surgery conducted by a trachoma control programme. Audit of trichiasis surgery should be routine.

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.

Le trachome : Une infection pédiatrique toujours d'actualité

Trachoma is a chronic granular conjunctivitis due to Chlamydia trachomatis serotypes A to C. The primary infection arises in the childhood while vision threatening complications occur in the adulthood. Vision decrease is mostly related to the opacification of the cornea which is due to the chronic friction of eyelashes on its surface (trichiasis), itself being a consequence of the conjunctival scarring secondary to relapsing infections. The trachoma rages in developing countries, not only in Africa but also and especially in Southeast Asia and in the region of the western Pacific. Even if the number of cases of trachoma in the world is now 6-fold lower than twenty years ago, still 83 millions of patients are affected by active trachoma, leading to the estimation that 490 millions of people should be treated in a curative or a preventive way. The fight against trachoma is based on the S.A.F.E. strategy, an acronym for surgery of trichiasis, antibiotics for patients and contact subjects, facial hygiene and environmental improvement. Concerning antibiotics, oral azithromycin is now considered as the gold standard for mass distribution against trachoma, but costs remain a major problem in developing countries. However, application of the four large-scale measures of the S.A.F.E. strategy should allow ending in the purpose fixed by the WHO organization, namely the Global Elimination of Trachoma by the year 2020.

The effect of antibiotic treatment on active trachoma and ocular Chlamydia trachomatis infection

Antibiotics are one of four arms of the SAFE strategy for the control of trachoma, an eye infection that is responsible for more cases of blindness than any condition other than cataract. The evidence for the use of topical tetracycline and oral tetracycline, doxycycline, erythromycin, cotrimoxazole and azithromycin in trachoma are reviewed here and a number of issues are nominated as research and policy priorities.

Effect of chronic systemic use of trimethoprim-sulfamethoxazole in the conjunctival bacterial flora of patients with HIV infection

PURPOSE

To investigate the effect of orally administered trimethoprim-sulfamethoxazole (TMP-SMZ) on the prevalence, species distribution, and resistance of the conjunctival bacterial flora in adults with human immunodeficiency virus (HIV) infection.

DESIGN

Cross-sectional study, with clinical and experimental laboratory investigation.

METHODS

Samples from the inferior conjunctival fornix were collected and submitted for culture to evaluate aerobic flora.

RESULTS

Sixty samples were collected. Negative cultures were found in 17 (56.7%) eyes of the TMP-SMZ group and in 10 (33%) of the control group (P = .036). All Staphylococcus species isolates in the TMP-SMZ group were resistant to the drug, whereas 50% of the control group presented this finding (P = .025). In the study group, all bacteria were resistant to TMP-SMZ, compared with only 47% of the microorganisms in the control group.

CONCLUSION

Orally administered TMP-SMZ in patients with HIV infection seems to exert a selection pressure in the microorganisms present on the conjunctiva.

Trachoma: new assault on an ancient disease

Trachoma is the leading infectious cause of blindness worldwide. The World Health Organization (WHO) estimated that approximately 5.9 million persons are blind or have severe vision-loss as a result of trachoma, and another 10 million are at high risk. Trachoma preferentially affects the most deprived communities, and within these communities, women and children bear the brunt of the burden. In recent years, there has been a renewed focus on research and heightened enthusiasm for strengthening trachoma control programs in afflicted countries. WHO has convened an alliance of member countries, non-governmental organizations, and other partners for the Global Elimination of Blinding Trachoma by the year 2020, and endorsed the multi-faceted SAFE strategy for trachoma control. SAFE-Surgery, Antibiotics, Face-washing, and Environmental improvement-has incorporated sound research on elements likely to reduce trachoma, and trachomatis blindness, in endemic communities. This review summarizes current knowledge about trachoma and its causative agent, Chlamydia trachomatis, the epidemiology and risk factors for trachoma as a prelude to reviewing the SAFE strategy. While ongoing research to support the knowledge base for SAFE must continue to be a priority, the full implementation of SAFE is the best hope for countries to reduce the global burden of blindness from this preventable cause.

Impact of azithromycin administration for trachoma control on the carriage of antibiotic-resistant Streptococcus pneumoniae

Community distribution of azithromycin has an important role to play in trachoma control. Previous studies have suggested that this may increase the prevalence of macrolide-resistant Streptococcus pneumoniae. S. pneumoniae was isolated from children under 7 years of age in Rombo District, northern Tanzania, before and 2 and 6 months after community-wide administration of azithromycin. Overall carriage rates were 11, 12, and 7%, respectively. Only one macrolide-resistant isolate carrying the mef gene was obtained 6 months after azithromycin administration. This contrasted with cotrimoxazole and penicillin resistance, both of which were common (cotrimoxazole resistance, 42, 43, and 47%, and penicillin resistance, 21, 17, and 16% at baseline, 2 months, and 6 months, respectively). There was a significant association between cotrimoxazole and penicillin resistance (P < 0.0001, Fisher's exact). These data suggest that in communities where macrolide resistance is rare, azithromycin distribution for trachoma control is unlikely to increase the prevalence of resistant organisms.

Strategies for control of trachoma: observational study with quantitative PCR

BACKGROUND

Antibiotics are an important part of WHO's strategy to eliminate trachoma as a blinding disease by 2020. At present, who needs to be treated is unclear. We aimed to establish the burden of ocular Chlamydia trachomatis in three trachoma-endemic communities in Tanzania and The Gambia with real-time quantitative PCR.

METHODS

Conjunctival swabs were obtained at examination from 3146 individuals. Swabs were first tested by the qualitative Amplicor PCR, which is known to be highly sensitive. In positive samples, the number of copies of omp1 (a single-copy C trachomatis gene) was measured by quantitative PCR.

FINDINGS

Children had the highest ocular loads of C trachomatis, although the amount of pooling in young age groups was less striking at the site with the lowest trachoma frequency. Individuals with intense inflammatory trachoma had higher loads than did those with other conjunctival signs. At the site with the highest prevalence of trachoma, 48 of 93 (52%) individuals with conjunctival scarring but no sign of active disease were positive for ocular chlamydiae.

INTERPRETATION

Children younger than 10 years old, and those with intense inflammatory trachoma, probably represent the major source of ocular C trachomatis infection in endemic communities. Success of antibiotic distribution programmes could depend on these groups receiving effective treatment.

Trachoma

Trachoma is the most common infectious cause of blindness. It is caused by ocular serovars of Chlamydia trachomatis. Transmission is favoured in poor communities, where crowding is common and access to water and sanitation inadequate. Repeated reinfection over many years causes dense scarring of the upper eyelid. The resultant inversion of the lashes abrades the eyeball, and the abrasion leads to corneal opacification and visual impairment. The host immune response is probably at least partly the cause of this process. The "SAFE" strategy is used for the control of trachoma: surgery for in-turned lashes, antibiotics for active disease, facial cleanliness, and environmental improvement. The demonstration that a single oral dose of the antibiotic azithromycin is as effective as 6 weeks of topical tetracycline was an important advance in trachoma control. By means of the SAFE strategy, WHO and its partners aim to eliminate trachoma as a public-health problem by the year 2020.

Polymorphisms in Chlamydia trachomatis tryptophan synthase genes differentiate between genital and ocular isolates

We previously reported that laboratory reference strains of Chlamydia trachomatis differing in infection organotropism correlated with inactivating mutations in the pathogen's tryptophan synthase (trpBA) genes. Here, we have applied functional genomics to extend this work and find that the paradigm established for reference serovars also applies to clinical isolates - specifically, all ocular trachoma isolates tested have inactivating mutations in the synthase, whereas all genital isolates encode a functional enzyme. Moreover, functional enzyme activity was directly correlated to IFN-gamma resistance through an indole rescue mechanism. Hence, a strong selective pressure exists for genital strains to maintain a functional synthase capable of using indole for tryptophan biosynthesis. The fact that ocular serovars (serovar B) isolated from the genital tract were found to possess a functional synthase provided further persuasive evidence of this association. These results argue that there is an important host-parasite relationship between chlamydial genital strains and the human host that determines organotropism of infection and the pathophysiology of disease. We speculate that this relationship involves the production of indole by components of the vaginal microbial flora, allowing chlamydiae to escape IFN-gamma-mediated eradication and thus establish persistent infection.

Pattern of antibiotic use in a trachoma-endemic region of Nepal: implications for mass azithromycin distribution

PURPOSE

To investigate antibiotic utilization in a rural district of western Nepal that is currently receiving azithromycin as part of a trachoma program and is being monitored by the Centers for Disease Control and Prevention (CDC) for drug resistance.

METHODS

Antibiotic purchase receipts were collected for 3 months from all medicine halls, pharmacies, and government sub-health posts in a sub-district of Western Nepal. Supplementary surveys of antibiotic sales were performed in different seasons.

RESULTS

Macrolides account for 3.9% of total antibiotic use, far less than quinolones, penicillins, tetracyclines, and sulfonamides.

CONCLUSIONS

If trachoma programs in Western Nepal generate transient macrolide resistance in pneumococcus and other bacteria, the epidemiological impact may not be great, as macrolides are not commonly used in the area.

Community treatment with azithromycin for trachoma is not associated with antibiotic resistance in Streptococcus pneumoniae at 1 year

AIMS

To determine if macrolide resistant Streptococcus pneumoniae will be a major concern in areas that receive annual mass azithromycin distributions for trachoma.

METHODS

A cross sectional survey was conducted of nasopharyngeal S pneumoniae isolates for susceptibility to azithromycin 1 year after administering a single dose of azithromycin to treat trachoma in a village in Nepal.

RESULTS

S pneumoniae was isolated from 50 (86%) of 57 nasopharyngeal cultures and no resistance to azithromycin was detected.

CONCLUSION

The authors were unable to demonstrate that mass azithromycin therapy for trachoma produced macrolide resistant S pneumoniae that persists until the next scheduled annual treatment.

Adverse and beneficial secondary effects of mass treatment with azithromycin to eliminate blindness due to trachoma in Nepal

Mass administration of azithromycin to eliminate blindness due to trachoma has raised concerns regarding the emergence of antimicrobial resistance. During 2000, we compared the antimicrobial resistance of nasopharyngeal pneumococcal isolates recovered from and the prevalence of impetigo, respiratory symptoms, and diarrhea among 458 children in Nepal before and after mass administration of azithromycin. No azithromycin-resistant pneumococci were isolated except from 4.3% of children who had received azithromycin during 2 previous mass treatments (P<.001). There were decreases in the prevalence of impetigo (from 14% to 6% of subjects; adjusted odds ratio [OR], 0.41; 95% confidence interval [CI], 0.21-0.80) and diarrhea (from 32% to 11%; adjusted OR, 0.26; 95% CI, 0.14-0.43) 10 days after azithromycin treatment. The absence of macrolide-resistant isolates after 1 mass treatment with azithromycin is encouraging, although the recovery of azithromycin-resistant isolates after 2 mass treatments suggests the need for resistance monitoring when multiple rounds of antimicrobial treatment are given.

Longitudinal study of trachomatous trichiasis in the Gambia

AIM

Investigation of the natural history of trachomatous trichiasis in the Gambia and of the outcome of self epilation and surgery for the condition.

METHODS

A 1 year longitudinal study of 190 subjects with trichiasis was performed. Major trichiasis cases (five lashes or more) were referred for surgery and minor trichiasis cases were advised to epilate. Outcome measures included progression of trichiasis and corneal scarring; attendance for and results of surgery.

RESULTS

34 of 148 (23%, 95% CI 16 to 31) subjects with major trichiasis attended for surgery over the year. Progression from minor to major trichiasis occurred in 18 of 55 subjects (33%, 95% CI 21 to 47). Progression of corneal scarring occurred in 60 of 167 patients (36%, 95% CI 29 to 44). Clinically active trachoma and conjunctival bacterial isolation predicted progression of corneal opacity. Surgery was successful in 39 of 54 (72%) eyes.

CONCLUSIONS

Despite the overall decline in trachoma in the Gambia, patients with both minor and major trichiasis remain at risk of developing corneal opacity. Active trachomatous inflammation and additional infection with bacteria may accelerate this process. Antibiotic treatment for trichiasis patients (in addition to surgery) should be investigated. Surgery for minor trichiasis may be indicated. Regular audit of surgical results is necessary with retraining where needed.

Reduction of trachoma in the absence of antibiotic treatment: evidence from a population-based survey in Malawi

PURPOSE

A survey was conducted in Chikwawa District, Malawi in order to compare the current prevalence of trachoma with a similar survey in 1983.

METHODS

Using random cluster household sampling, children aged 1 to 6 and adults aged 50 or older were enumerated and examined for the presence of trachoma.

RESULTS

Among the 1313 children enumerated, 1249 (95.1%) were examined and among the 1431 adults enumerated, 1221 (85.3%) were examined. The prevalence of active trachoma among the children was 13.9% (11.9-15.9%), 10.0% in males and 14.4% in females. The prevalence of active trachoma varied significantly among the 25 clusters, ranging from 3.9% to 38.2% with 5 clusters (20%) having a prevalence >20%. Signs of trachomatous trichiasis were observed in 1.0% of adults examined. Active disease in 1999 was associated with a longer distance to the primary water source.

CONCLUSIONS

Since 1983 there has been no mass antibiotic treatment programme in the district and little change in socioeconomic status. However, compared to the 1983 findings, active trachoma has been reduced by over 50% (p < 0.001) and trachomatous trichiasis by over 80%. In the 16-year interim (especially in the past 7 years) health, water and hygiene programmes were initiated and we hypothesize that the reduction in active disease is likely due to these changes. Our findings suggest that sustained reductions in active trachoma can be achieved without community-based antibiotic distribution.