(P255) Detection of gyrA mutations in Mycoplasma genitalium from individuals who failed treatment

Background: Whilst macrolide resistance in Mycoplasma genitalium (MGEN) is well-characterised, fluoroquinolone resistance is less well understood. Specific mutations (S83I, S83R, D87N and D87Y) in the quinolone-resistance determining region (QRDR) of the parC gene are associated with fluoroquinolone treatment failure, with additional mutations in the gyrA gene proposed to have a synergistic effect. In particular it has been suggested that the presence of the S83I parC mutation as well as gyrA mutation may increase the likelihood of treatment failure. We investigated the prevalence of gyrA mutations in MGEN-positive clinical specimens referred to the UK Health Security Agency, from individuals who remained positive post-treatment, with resistance-associated mutations in the parC gene.

Methods: All fluoroquinolone-resistant (parC: S83I, S83R and D87N), MGEN-positive test-of-cure clinical specimens (n=39, 27 urine, 1 urethral swab, 5 vaginal swabs and 6 unknown from 24 male, 7 female and 2 unknown individuals), referred to UKHSA (30.11.2021-07.11.2022), were selected. DNA was extracted using the QIAsymphony DSP Virus/Pathogen Midi Kit (Qiagen). The MGEN gyrA gene was amplified using real-time PCR on the Quantstudio 5 platform followed by Sanger sequencing. gyrA sequences were mined for the presence of mutations in the QRDR using BioNumerics (Applied Maths).

Results: Sequence data for gyrA was available for 28/39 (72%) specimens from 28 individuals; 22/28 (79%) were wild-type, 6/28 (21%) were mutated (Table 1). The D99G, D99N and D99Y mutations were reported in 1/6 (17%), 4/6 (67%) and 1/6 (17%) specimens respectively. Most mutated specimens (5/6, 83%) had the S83I parC mutation. No novel mutations were identified. All specimens had mutations conferring macrolide resistance in the 23S rRNA gene. Treatment and clinical outcome data was unavailable.

Conclusions: We report a high prevalence (21%) of mutations in the QRDR of the gyrA gene with predicted moxifloxacin resistance (indicated by mutations in the parC gene). Whilst no treatment data was available, all were sourced from individuals who remained positive post-treatment. The combination of parC/gyrA mutations suggested to increase the risk of treatment failure was detected. Surveillance of the prevalence of parC and gyrA mutations and linkage to treatment data is imperative to retain MGEN as a treatable infection.