Abstract

Objectives: To evaluate the microbiological cure rate after treatment with tetracyclines or azithromycin in patients infected with M. genitalium.

Methods: One hundred and fifty-two men and 60 women positive for M. genitalium were recruited. Patients treated either with doxycyline for 9 days or with azithromycin 1 g stat were compared. Those still positive for M. genitalium after primary doxycycline treatment received an extended course of azithromycin 500 mg on day 1 followed by 250 mg daily for the following 4 days whereas those with treatment failure after azithromycin received doxycycline 100 mg bid for 15 days.

Results: The eradication rate after azithromycin 1g stat. was 85% (95% CI 69 to 94) in men (n=39) and 88% (95% CI 64 to 99) in women (n=17) and after doxycycline 17% (95% CI 9 to 27) in men (n=76) and 37% (95% CI 19 to 58) in women (n=27). Extended azithromycin eradicated M. genitalium from 96% (95% CI 85 to 99) of the men (n=47) and from all 6 women who failed on doxycycline. Extended doxycycline treatment was insufficient. Persistent urethral inflammation was seen in a substantial portion of the men after eradication of M. genitalium regardless of the antibiotic drug, indicating a poor predictive value of urethral smears in evaluation of persistent or recurrent infection.

Conclusions: Azithromycin was more effective than doxycycline in treating patients infected with M. genitalium. The extended course of azithromycin was highly effective but was given after the initial treatment with doxycycline. Randomized clinical trials are needed to compare the different dosages of azithromycin. Footnote: Parts of this study were presented at the 15th Meeting of the International Society for Sexually Transmitted Diseases Research, Ottawa, Canada, July 2003.