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Clinical Science

Category: Mycoplasma genitalium

(P245) Treating Mycoplasma genitalium Infection with a Sitafloxacin Regimen in the Context of Increased Resistance

Tuesday, July 25, 2023
16:00 – 18:00 CST
Background
Mycoplasma genitalium is a sexually transmitted bacterium with an evolving resistance profile. Macrolide resistance in M. genitalium exceeds 50% in many regions, and fluoroquinolone resistance is rising. Current practice in Australia follows macrolide-resistance guided therapy. Patients with macrolide-resistant M. genitalium receive doxycycline followed by moxifloxacin as first-line treatment. At Melbourne Sexual Health Centre (MSHC), patients who fail moxifloxacin are treated second-line with a sitafloxacin-containing regimen. We conducted an audit to evaluate the efficacy of sitafloxacin-containing regimens for macrolide-resistant M. genitalium.



Methods
Patients with macrolide-resistant M. genitalium treated with sitafloxacin at MSHC between January 2017-February 2022 were included. Two sitafloxacin regimens were used during the study period: before October 2017 patients received sequential monotherapy (doxycycline followed by sitafloxacin); subsequently, patients received combination therapy (doxycycline followed by doxycycline+sitafloxacin). Microbial cure was defined as a negative test-of-cure 14-90 days after completing sitafloxacin. Proportions and 95% confidence intervals (CI) were calculated. Logistic regression was used to explore factors associated with sitafloxacin failure. Factors associated with treatment failure in univariable analyses were included in multivariable analysis.



Results
232 patients with M. genitalium (representing 235 infections) were treated with a sitafloxacin-containing regimen. Microbial cure following sitafloxacin was 80.4% (95%CI:74.8-85.3, 189/235). In analyses adjusted for age, gender, prior failure of moxifloxacin and M. genitalium test-of-cure assay, prior failure of moxifloxacin was the only factor associated with sitafloxacin failure (Adjusted-Odds-Ratio=7.93, 95%CI:2.49-25.23, p< 0.001). Due to correlated variables, we stratified cure based on prior moxifloxacin failure to evaluate the efficacy of the two sitafloxacin regimens. We found no significant difference in cure following sequential monotherapy vs combination therapy among patients who had previously failed moxifloxacin (2/6 [33.3%] vs 87/122 [71.3%], p=0.069) or among those who had not previously failed moxifloxacin (87/92 [94.6%] vs 11/12 [91.7%], p=0.530), although small numbers limited comparisons.



Conclusion
The overall cure following sitafloxacin was 80.4%. Failure was 8-fold higher among patients who had previously failed moxifloxacin, which is likely due to increases in specific fluoroquinolone resistance mutations (i.e. S83I) in Melbourne over this period. These data provide information about the efficacy of sitafloxacin for macrolide-resistant M. genitalium and highlight the need for next-generation resistance-guided therapy.