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

BACKGROUND/AIMS The World Health Organisation has recommended repeated mass treatment of children in trachoma endemic areas with oral azithromycin. While chlamydia, the causative agent of trachoma, remains universally sensitive to azithromycin, there is concern that large scale programmes may alter the bacterial flora and induce resistance in streptococcal species. In this study the effect of a single dose of azithromcyin on the prevalence, species distribution, and resistance of conjunctival bacterial flora was determined. METHODS Baseline and 14 day follow up bacterial cultures were taken from the conjunctivae of 121 children who reside in a trachoma endemic area of Nepal. 91 children were treated with azithromycin at baseline and 31 children received deferred treatment at the 14 day follow up. RESULTS Although the prevalence of bacterial pathogens decreased significantly with azithromycin treatment, a significant change in the distribution of specific bacterial pathogens could not be demonstrated. Streptococcal resistance to azithromycin was found significantly more frequently after treatment. No change in the prevalence, distribution, or resistance pattern was found in the untreated control group. CONCLUSION Repeated mass treatment of trachoma endemic areas with oral azithromycin will have an effect on bacterial flora. However, further work needs to be done to determine if this will have any clinical relevance.