Resistance-Guided Antimicrobial Therapy Using Doxycycline-Moxifloxacin And Doxycycline-2.5 G Azithromycin For The Treatment Of Mycoplasma Genitalium Infection: Efficacy And Tolerability

Background Macrolide resistance in Mycoplasma genitalium (MG) exceeds 50% in many regions, and quinolone resistance is increasing. We recently reported that resistance-guided therapy (RGT) using doxycycline followed by sitafloxacin or 2.5 g azithromycin cured 92% and 95% of macrolide-resistant and macrolide-susceptible infections, respectively. We present data on RGT using doxycycline-moxifloxacin, the regimen recommended in international guidelines, and extend data on the efficacy of doxycycline-2.5 g azithromycin and de novo macrolide resistance.Methods Patients attending Melbourne Sexual Health Centre between 2017 and 2018 with sexually transmitted infection syndromes were treated with doxycycline for 7 days and recalled if MG-positive. Macrolide-susceptible cases received 2.5 g azithromycin (1 g, then 500 mg daily for 3 days), and resistant cases moxifloxacin (400 mg daily, 7 days). Test of cure was recommended 14-28 days post-antimicrobials.Results There were 383 patients (81 females/106 heterosexual males/196 men who have sex with men) included. Microbial cure following doxycycline-azithromycin was 95.4% (95% confidence interval [CI], 89.7-98.0) and doxycycline-moxifloxacin was 92.0% (95% CI, 88.1-94.6). De novo macrolide resistance was detected in 4.6% of cases. Combining doxycycline-azithromycin data with our prior RGT study (n = 186) yielded a pooled cure of 95.7% (95% CI, 91.6-97.8). ParC mutations were present in 22% of macrolide-resistant cases.Conclusions These findings support the inclusion of moxifloxacin in resistance-guided strategies and extend the evidence for 2.5 g azithromycin and presumptive use of doxycycline. These data provide an evidence base for current UK, Australian, and European guidelines for the treatment of MG.Mycoplasma genitalium is challenging to cure due to increasing resistance to antimicrobials. Resistance-guided therapy using doxycycline followed by azithromycin or moxifloxacin achieves high levels of microbiological cure (>92%) and low levels of de novo resistance.