Changes in prevalence of Mycoplasma genitalium macrolide and fluoroquinolone resistance: notes from a 13-year retrospective survey in Dalarna County, Sweden.

OBJECTIVE: Macrolide and fluoroquinolone resistance in Mycoplasma genitalium (MG) is of emerging global concern. Compared with neighbouring countries such as Denmark, Sweden has had lower rates of macrolide resistance while fluoroquinolone resistance rates are less well documented. This study retrospectively examined macrolide, fluoroquinolone and multidrug resistance rates from Dalarna County, Sweden over a 13-year period. METHODS: MG-positive samples from 2006 to 2018 from patients examined at the Department of Venereology, Central Hospital, Falun, Sweden were tested by sequencing for macrolide resistance mutations (MRM) and fluoroquinolone resistance-associated mutations (QRAM) in the parC and gyrA subunit regions. A subset of these samples from 2006 to 2011 have been reported on previously, although only for MRM. RESULTS: Of 874 samples, 98 (11.2%, 95% CI 9.1% to 13.6%) had mutations associated with resistance to macrolides and 19 of 828 (2.3%, 95% CI 8.9% to 23.1%) to quinolones. Mutations associated with resistance to both drugs were detected in 5 of 828 (0.6%, 95% CI 0.1% to 1.4%) samples overall. A significant positive linear trend (p=0.004) for an increase in the rate of macrolide resistance was observed (from 0% in 2006 to 31% in 2018) while the increase in QRAM from 0% in 2006 to 12.3% in 2018 was not statistically significant. CONCLUSIONS: Despite a decrease in macrolide and fluoroquinolone consumption in Sweden, there was an overall increase in MG macrolide, fluoroquinolone and dual resistance from 2006 to 2018, although the difference in fluoroquinolone resistance rates was not statistically significant. In order to maintain comparably low resistance rates, resistance-guided therapy for MG infections will be crucial.

Evaluation of the ResistancePlus MG FleXible Assay for Detection of Wild-Type and 23S rRNA-Mutated Mycoplasma genitalium Strains.

Antibiotic resistance in Mycoplasma genitalium is rising globally, and resistance-guided diagnostics can facilitate targeted and timely treatment. The ResistancePlus MG FleXible (RPMG Flex) assay for the detection of M. genitalium and macrolide resistance-mediating mutations (MRMM) was evaluated for analytical sensitivity, specificity, reproducibility, and inhibition in the presence of interfering substances by simulating M. genitalium-negative pooled urine and swab matrices with M. genitalium cultures. Furthermore, the clinical sensitivity of the assay was evaluated and compared with a reference real-time PCR assay. The analytical sensitivity of the RPMG Flex assay was 157 genomes/ml for wild-type (WT) and 387 genomes/ml for MRMM strains in both matrices. For clinical specimens, the RPMG assay had an overall sensitivity of 96.1% (95% urine: 10/10 WT, 9/10 MRMM; 96.5% swab: 25/26 WT, 26/29 MRMM) compared to 85.7% for the MgPa/MagNAPure24 assay (95% urine: 19/20; 87% swab: 48/57). Clinical specificity was 100% for urine and 98.5% for swab specimens, respectively. No inhibition due to the presence of any of the tested interfering substances was observed. The RPMG Flex assay was more sensitive than the reference MgPa assay, in particular, for swab specimens. The implementation of this assay may increase ease of use and considerably decrease hands-on time for sample preparation compared to a standard block-based assay. The RPMG Flex assay for the GeneXpert Dx system provides a much-needed platform for the simultaneous detection of MG and MRMM and may thereby facilitate resistance-guided therapy for M. genitalium infections.