Persistence of Mycoplasma genitalium Following Azithromycin Therapy

Background: To determine clinical outcomes and cure rates for M. genitalium genital infection in men and women following azithromycin 1 g. Methodology: Patients attending Melbourne Sexual Health Centre between March 2005 and November 2007 with urethritis/epididymitis, cervicitis/pelvic inflammatory disease and sexual contacts of M. genitalium were tested for M. genitalium by polymerase chain reaction (PCR). M. genitalium-infection was treated with 1 g of azithromycin and a test-of-cure (toc) was performed one month post-azithromycin. Response to azithromycin, and response to moxifloxacin (400 mg daily for 10 days) in individuals with persistent infection post-azithromycin, was determined. Principal Findings: Of 1538 males and 313 females tested, 161 males (11%) and 30 females (10%) were infected with M. genitalium. A toc was available on 131 (69%) infected individuals (median = 36 days [range 12-373]). Of 120 individuals prescribed azithromycin only pre-toc, M. genitalium was eradicated in 101 (84%, 95% confidence intervals [CI]: 77-90%) and persisted in 19 (16%, 95% CI: 10-23%). Eleven individuals with persistent infection (9%, 95% CI: 5-15%) had no risk of reinfection from untreated-partners, while eight (7%, 95% CI: 3-12%) may have been at risk of reinfection from doxycycline-treated or untreated-partners. Moxifloxacin was effective in eradicating persistent infection in all cases not responding to azithromycin. Patients with persistent-M. genitalium were more likely to experience persistent symptoms (91%), compared to patients in whom M. genitalium was eradicated (17%), p<0.0001. Conclusion: Use of azithromycin 1 g in M. genitalium-infected patients was associated with unacceptable rates of persistent infection, which was eradicated with moxifloxacin. These findings highlight the importance of follow-up in M. genitalium-infected patients prescribed azithromycin, and the need to monitor for the development of resistance. Research to determine optimal first and second-line therapeutic agents for M. genitalium is needed.