Detection of parC gene mutations associated with quinolone resistance in Mycoplasma genitalium: evaluation of a multiplex real-time PCR assay

Genetic Determinants of Macrolide and Fluoroquinolone Resistance in Mycoplasma genitalium and Their Prevalence in Moscow, Russia

Macrolide (MLR) and fluoroquinolone (FQR) resistance in Mycoplasma genitalium (MG) has recently become a major problem worldwide. The available data on the prevalence of MLR and FQR in MG in Russia are limited. In this study, we aimed to evaluate the prevalence and pattern of mutations in 213 MG-positive urogenital swabs from patients in Moscow between March 2021 and March 2022. MLR- and FQR-associated mutations were searched in 23S rRNA as well as in the parC and gyrA genes using Sanger sequencing. The prevalence of MLR was 55/213 (26%), with A2059G and A2058G substitutions being the two most common variants (36/55, 65%, and 19/55, 35%, respectively). FQR detection showed 17% (37/213); two major variants were D84N (20/37, 54%) and S80I (12/37, 32.4%) and three minor variants were S80N (3/37, 8.1%), D84G (1/37, 2.7%), and D84Y (1/37, 2.7%). Fifteen of the fifty-five MLR cases (27%) simultaneously harbored FQR. This study revealed the high frequency of MLR and FQR. We conclude that the improvement of patient examination algorithms and therapeutic approaches should be combined with the routine monitoring of antibiotic resistance based on the sensitivity profiles presented. Such a complex approach will be essential for restraining the development of treatment resistance in MG.

Clinical Performance of Three Commercial Molecular Diagnostic Assays for the Detection of Fluoroquinolone Resistance-Associated Mutations in Mycoplasma genitalium

The high prevalence of macrolide resistance in Mycoplasma genitalium results in an increased reliance on moxifloxacin, the second-line treatment; however, moxifloxacin resistance has also emerged. Because assays that can detect fluoroquinolone resistance-associated mutations will be useful for the management of macrolide-resistant M. genitalium infections, we evaluated the performance of three commercial assays (the Allplex MG & MoxiR Assay [Seegene], LightMix Modular parC kit [TIBMOLBIOL], and MGMO qPCR [NYtor) in comparison with parC gene Sanger sequencing used as the reference. Between January 2018 and December 2020, remnants of M. genitalium-positive clinical specimens received at the French National Reference Center for Bacterial Sexually Transmitted Infections were collected if a Sanger sequencing result was obtained for the parC gene. Overall, 368 M. genitalium-positive specimens were assessed. The clinical sensitivities for the detection of the ParC mutations that are likely of clinical significance were 91.8% (95% CI = 83.2 to 96.2), 98.6% (95% CI = 92.4 to 99.8), and 94.4% (95% CI = 86.6 to 97.8) for the Allplex MG & MoxiR, LightMix Modular parC, and MGMO qPCR kits, respectively, with no significant difference between the three kits. The clinical specificity of the Allplex MG & MoxiR and MGMO qPCR kits was 100% (95% CI = 97.7 to 100 and 98.7 to 100, respectively), which was significantly higher than the specificity of the LightMix Modular parC kit of 95.4% (95%CI = 92.3 to 97.3), for which the interpretation of melting curves may be misleading. These kits should be useful for the selection of antimicrobials in macrolide-resistant M. genitalium infections, although further developments may be necessary because parC mutations involved in fluoroquinolone resistance have not been precisely determined.

Prevalence of macrolide and fluoroquinolone resistance-associated mutations in Mycoplasma genitalium in metropolitan and overseas France

Objective

Limited macrolide and fluoroquinolone resistance data are available in France for Mycoplasma genitalium. We performed a multicentre cross-sectional study to investigate the prevalence of macrolide and fluoroquinolone resistance-associated mutations in M. genitalium-positive patients in metropolitan France between 2018 and 2020 and in overseas France in 2018 and 2019.

Methods

Each year, a 1-month prospective collection of M. genitalium-positive specimens was proposed to metropolitan French microbiology diagnostic laboratories, and a similar 3-month collection was proposed to overseas French laboratories. Resistance-associated mutations were detected using commercial kits and sequencing.

Results

A total of 1630 M. genitalium-positive specimens were analysed. In metropolitan France, the prevalence of macrolide resistance-associated mutations ranged between 34.7% (95% CI 29.4% to 40.4%) and 42.9% (95% CI 37.1% to 49.0%) between 2018 and 2020 and was significantly higher in men (95% CI 52.4% to 60.2%) than in women (95% CI 15.9% to 22.2%) (p<0.001). These prevalences were significantly higher than those of 6.1% (95% CI 3.7% to 10.3%) and 14.7% (95% CI 10.9% to 19.6%) observed in overseas France in 2018 and 2019 (p<0.001), where no difference between genders was noted. The prevalence of fluoroquinolone resistance-associated mutations was also significantly higher in metropolitan France (14.9% (95% CI 11.2% to 19.5%) to 16.1% (95% CI 12.1% to 21.2%)) than in overseas France (1.3% (95% CI 0.4% to 3.7%) and 2.6% (95% CI 1.3% to 5.3%) in 2018 and 2019, respectively) (p<0.001), with no difference between men and women regardless of the location.

Conclusion

This study reports the high prevalence of macrolide and fluoroquinolone resistance-associated mutations in M. genitalium in metropolitan France and highlights the contrast with low prevalence in overseas France. In metropolitan France, macrolide resistance-associated mutation prevalence was three times higher in men than in women, which was likely to be driven by the proportion of men who have sex with men. This suggests that gender and sexual practice should also be taken into account for the management of M. genitalium infections.

Rapid Detection of Antimicrobial Resistance in Mycoplasma genitalium by High-Resolution Melting Analysis with Unlabeled Probes

With looming resistance to fluoroquinolones in Mycoplasma genitalium, public health control strategies require effective antimicrobial resistance (AMR) diagnostic methods for clinical and phenotypic AMR surveillance. We developed a novel AMR detection method, MGparC-AsyHRM, based on the combination of asymmetric high-resolution melting (HRM) technology and unlabeled probes, which simultaneously performs M. genitalium identification and genotypes eight mutations in the parC gene that are responsible for most cases of fluoroquinolone resistance. These enhancements expand the traditional HRM from the conventional detection of single-position mutations to a method capable of detecting short fragments with closely located AMR positions with a high diversity of mutations. Based on the results of clinical sample testing, this method produces an accordance of 98.7% with the Sanger sequencing method. Furthermore, the specificity for detecting S83I, S83N, S83R, and D87Y variants, the most frequently detected mutations in fluoroquinolone resistance, was 100%. This method maintained a stable and accurate performance for genomic copies at rates of ≥20 copies per reaction, demonstrating high sensitivity. Additionally, no specific cross-reactions were observed when testing eight common sexually transmitted infection (STI)-related agents. Notably, this work highlights the significant potential of our method in the field of AMR testing, with the results suggesting that our method can be applied in a range of scenarios and to additional pathogens. In summary, our method enables high throughput, provides excellent specificity and sensitivity, and is cost-effective, suggesting that this method can be used to rapidly monitor the molecular AMR status and complement current AMR surveillance. IMPORTANCE Mycoplasma genitalium was recently added to the antimicrobial-resistant (AMR) threats "watch list" of the U.S. Centers for Disease Control and Prevention because this pathogen has become extremely difficult to treat as a result of increased resistance. M. genitalium is also difficult to culture, and therefore, molecule detection is the only method available for AMR testing. In this work, we developed a novel AMR detection method, MGparC-AsyHRM, based on the combination of asymmetrical HRM technology and unlabeled probes, and it simultaneously performs M. genitalium identification and genotypes eight mutations in the parC gene that are responsible for most cases of fluoroquinolone resistance. The MGparC-AsyHRM method is a high-throughput, low-cost, simple, and culture-free procedure that can enhance public health and management of M. genitalium infections and AMR control, providing a strong complement to phenotypic AMR surveillance to address the spread of fluoroquinolone resistance.

COVID-19 Australia: Epidemiology Report 52 Reporting period ending 10 October 2021

This is the fifty-second epidemiological report for coronavirus disease 2019 (COVID-19), reported in Australia as at 23:59 Australian Eastern Daylight Time [AEDT] 10 October 2021. It includes data on COVID-19 cases diagnosed in Australia and the international situation.

Prevalence of Mycoplasma genitalium fluoroquinolone-resistance markers, and dual-class-resistance markers, in asymptomatic men who have sex with men

Introduction. Failure of fluoroquinolones, the principal treatment option for macrolide-resistant Mycoplasma genitalium infections, has recently emerged. This is of particular concern for men who have sex with men (MSM), who have high proportions of macrolide-resistant M. genitalium infections. Treatment failure with moxifloxacin is likely the result of single nucleotide polymorphisms (SNPs) in parC, whilst concurrent gyrA mutations may play a role.Gap Statement. The levels of fluoroquinolone resistance and dual-class (i.e. macrolide and fluoroquinolone) resistance in M. genitalium among asymptomatic MSM is unknown.Aim. To (i) determine the proportion of fluoroquinolone resistance and dual-class resistance in M. genitalium infections among asymptomatic MSM, (ii) explore any clinical and behavioural associations with fluoroquinolone resistance, and (iii) determine the distribution of antibiotic resistance among M. genitalium mgpB sequence types (STs).Methodology. M. genitalium positive samples (N=94) were obtained from 1001 asymptomatic MSM enrolled in a study at Melbourne Sexual Health Centre (Carlton, Australia) between August 2016 and September 2017. Sanger sequencing was performed to determine the proportion of M. genitalium infections with SNPs in parC that have previously been associated with failure of moxifloxacin (corresponding to amino changes S83I, D83R, D87Y and D87N) and in gyrA (corresponding to amino acid changes M95I, D99N, D99Y and D99G). Associations between clinical/behavioural factors and parC SNPs were examined. Strain typing was performed by sequencing a portion of the mgpB gene.Results. The proportion of MSM with infections harbouring parC and gyrA SNPs was 13.0 % [95 % confidence interval (CI): 6.8-23.2 %] and 4.7 % (95 % CI: 1.1-13.4 %), respectively; dual-class resistance was 13.0 %. No significant clinical/behavioural associations were found. Antibiotic resistance was not restricted to specific mgpB STs.Conclusion. One in eight (13 %) of asymptomatic MSM with M. genitalium had an infection with dual-class-resistance mutations. Typing by mgpB sequence suggested fluoroquinolone resistance is arising from independent mutation events. This study illustrates that asymptomatic MSM may act as a reservoir for antibiotic-resistant M. genitalium.

COVID-19 Australia: Epidemiology Report 48 Reporting period ending 15 August 2021

This is the forty-eighth epidemiological report for coronavirus disease 2019 (COVID-19), reported in Australia as at 23:59 Australian Eastern Standard Time [AEST] 15 August 2021. It includes data on COVID-19 cases diagnosed in Australia and the international situation.