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 twice daily for 15 days.
Results: The eradication rate after azithromycin 1 g 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 six 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. Randomised clinical trials are needed to compare the different dosages of azithromycin.