Persistence of Mycoplasma genitalium following azithromycin therapy

Abstract

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.

Figure 1

* = cases with no risk of reinfection from untreated sexual partner, d = days, C1 = case 1, C2 = case 2, (A1) = first occasion 1 g azithromycin administered, (A2) = second occasion 1 g azithromycin administered, (M1) = first occasion 400 mg daily of moxifloxacin for 10 days administered, (D1) = first occasion 100 mg bd doxycycline for 7 days administered, SP = sexual partner, no Rx = no treatment administered, toc1 = first test of cure for case, toc2 = second test of cure for case, + = positive, − = negative, NA =  not available, ^#sp not retreated with azithromycin after first occasion, ? = treatment advised but could not be verified.