Background Macrolide-resistance in Mycoplasma genitalium (MG) exceeds 50% in many nations and increasing quinolone-resistance is reported. Recent data showed resistance-guided therapy (RGT) using doxycycline then sitafloxacin for macrolide-resistant MG cured 92% of infections and doxycycline-azithromycin for macrolide-susceptible MG cured 95%. As sitafloxacin is not widely available, we undertook a study of RGT to evaluate the efficacy of moxifloxacin in RGT to provide data that is relevant to international guidelines and to assess the efficacy of this alternative approach in a population with 15–20% quinolone-resistance (ParC mutations).

Methods Patients attending Melbourne Sexual Health Centre between April 2017-June 2018 with urethritis, cervicitis or proctitis were treated with doxycycline (7 days)and recalled if positive for MG. Macrolide-susceptible cases received azithromycin (1g, then 500 mg daily 3 days)and resistant-cases received moxifloxacin (400 mg daily, 7 days). Patients attended for test of cure (TOC) following treatment. Adherence and side effects were recorded. Patients were included in the efficacy analysis if they were treated in accordance with RGT protocol, were not at high risk of reinfection and had a 14–90 day TOC.

Results 382 participants (80 female/106 heterosexual male/196 MSM) were included: 109 (28.5%) had macrolide-susceptible MG and 273(71.5%) macrolide-resistant MG. Doxycycline-azithromycin cure was 95.4% (95%CI 89.7–98%) and doxycycline-moxifloxacin cure was 91.9% (95%CI 88.1–94.6%). Median time to TOC was 27 days (IQR=22–35). Doxycycline-azithromycin data was combined with our prior RGT study and the pooled estimate of cure (n=186) was 95.2% (95%CI 91.1–97.4%). Analysis of selected macrolide resistance is underway but will not exceed 4.3% (95%CI 2.2–8.6%).

Conclusion Despite 15–20% quinolone resistance in Melbourne the sequential strategy of doxycycline-moxifloxacin achieved unexpectedly high cure (92%), and did not differ to doxycycline-sitafloxacin, a more effective quinolone, suggesting preceding doxycycline may improve cure through reducing pre-treatment load. Doxycycline followed by azithromycin for susceptible infections consistently achieves 95% cure and low levels of selected resistance (<5%).

Disclosure No significant relationships.