Time to eradication of Mycoplasma genitalium after antibiotic treatment in men and women

Lars Falk, Martin Enger, Jørgen Skov Jensen

The objectives of this study were to evaluate the time to a Mycoplasma genitalium-negative test after start of treatment and to monitor if and when antibiotic resistance developed. Sexually transmitted disease (STD) clinic attendees with suspected or verified M. genitalium infection were treated with azithromycin (5 days, 1.5 g; n = 85) or moxifloxacin (n = 5). Subjects with symptomatic urethritis or cervicitis of unknown aetiology were randomized to either doxycycline (n = 49) or 1 g of azithromycin as a single dose (n = 51). Women collected vaginal specimens and men collected first-catch urine 12 times during 4 weeks. Specimens were tested for M. genitalium with a quantitative MgPa PCR and for macrolide resistance-mediating mutations with a PCR targeting 23S rRNA. NCT01661985. Ninety M. genitalium cases were enrolled. Of 56 patients with macrolide-susceptible strains before treatment with azithromycin (1.5 g, n = 46; 1 g single oral dose, n = 10), 54 (96%) had a negative PCR test within 8 days. In four patients, M. genitalium converted from macrolide susceptible to resistant after a 10 day lag time with negative tests (azithromycin 1.5 g, n = 3; 1 g single oral dose, n = 1). Moxifloxacin-treated subjects (n = 4) were PCR negative within 1 week. Six of eight (75%) remained positive despite doxycycline treatment. PCR for M. genitalium rapidly became negative after azithromycin treatment. Macrolide-resistant strains were detected after initially negative tests. Test of cure should be recommended no earlier than 3-4 weeks.