Prevalence of Mycoplasma genitalium infection with antimicrobial resistance mutations among gay sex workers in China

Prolonged sitafloxacin and doxycycline combination regimen for treating infections by highly resistant Mycoplasma genitalium

BACKGROUND

Mycoplasma genitalium, which causes sexually transmitted diseases, is increasingly resistant to key antibiotics such as macrolides and quinolones, posing a challenge for treatment.

OBJECTIVES

To assess the effectiveness of prolonged sitafloxacin and doxycycline combination therapy as a new alternative treatment strategy for highly drug-resistant M. genitalium strains.

METHODS

A prospective cohort study was conducted at the National Center for Global Health and Medicine, Tokyo, Japan, from 1 January 2020 to 31 October 2022. Patients with M. genitalium urogenital or rectal infections and those who did not receive the initial sitafloxacin monotherapy were included. Patients were administered sitafloxacin and doxycycline for 21 days as salvage therapy. M. genitalium isolates were tested for parC, gyrA and 23S rRNA resistance-associated mutations.

RESULTS

Twenty-seven patients received the combination therapy. All M. genitalium strains available for resistance analysis had parC (24/24) and macrolide resistance-associated (25/25) mutations, and 68% (17/25) had gyrA mutations. The overall cure rate was 77.8%. For strains with concurrent parC and gyrA mutations, the cure rate was 68.8% (P = 0.053) compared with that for monotherapy (37.5%).

CONCLUSIONS

Prolonged combination therapy is highly effective against M. genitalium strains with concurrent parC and gyrA mutations. Future research should focus on establishing the optimal treatment duration and monitoring the risk of resistance.

Detection of resistance to macrolides and fluoroquinolones in Mycoplasma genitalium by targeted next-generation sequencing

Mycoplasma genitalium is fastidious to culture, and its detection in human clinical specimens relies mainly on molecular methods. Phenotypic determination of antibiotic susceptibility for this bacterium is not a timely or feasible option for most clinical laboratories. This study sought to determine whether next-generation sequencing technologies can effectively be employed in determining genetic mutations associated with drug resistance in M. genitalium samples collected in Aptima Hologic tubes and possibly integrating them into viable workflows in public health laboratories. Following analysis by a custom-designed bioinformatics pipeline, at least one mutation/sample has been identified in 94/98 specimens in at least one of seven loci (macrolides: rrl, rplD, rplV; fluoroquinolones: parC, parE, gyrA, gyrB) described previously to be connected to antibiotic resistance. This method identified a total of 469 single nucleotide polymorphisms (SNPs) (452 mutations): 134 of 23S rRNA SNPs and 318 amino acid mutations: 114 substitutions and 204 synonymous; the turnaround time (sample to analyzed sequence) was typically 3 days. The assays and workflows described in this work demonstrated that the determination of a drug resistance profile for macrolides and fluoroquinolones of M. genitalium samples by using next-generation sequencing in clinical samples is a feasible approach that can be implemented in clinical laboratories, following thorough and extensive validation studies.IMPORTANCEThe mechanisms of drug resistance in Mycoplasma genitalium are complex and involve several genetic loci. The molecular methods for accurately characterizing resistance to fluoroquinolones and macrolides in this organism are often not available or approved for patient use and do not cover all genetic determinants. To this end, we propose a next-generation sequencing-based method with a turnaround time of 3 days that includes the investigation of all drug resistance loci of M. genitalium. Following adaptation, validation, and verification for routine clinical use, assays based on this method may yield molecular results that can be used to guide proper treatment regimens and for surveillance of drug resistance in the general population.