An automated commercial open access assay for detection of Mycoplasma genitalium macrolide resistance

Azithromycin, a macrolide antibioticum, is the first-line treatment for Mycoplasma genitalium (MG), but resistant MG is an increasing problem. Macrolide resistance-mediated mutations (MRM) has been linked to point mutations in region V of the MG 23S rRNA gene. We have evaluated an open access analyzer (Panther Fusion, Hologic Inc) for detectability of MRM (mutations A2071G and A2072G) and MG wild type (WT) in clinical samples. Also, the agreement of the Panther Fusion assay results with a corresponding established In-house MRM-WT PCR (ABI 7500) was calculated. Left over material from 55 clinical samples positive for MG by the Aptima test (Hologic) based on transcription-mediated amplification (TMA), collected from January to February 2023 in Region Skåne, Sweden, was analyzed. Specific amplification curves were generated for positive controls of MG mutations (A2071G and A2072G) and WT by the Panther Fusion assay. The limit of detection (LOD) was 5.3 copies/mL for WT, 8.1 copies/mL for mutation A2071G, and 81 copies/mL for mutation A2072G. The overall concordance was 91% between the Panther Fusion and the In-house PCR (Kappa 0.621, 95% CI; 0.327-0.914) for detection of WT or MRM in MG-positive clinical samples. The Panther Fusion detected MRM in 20% (11/55) and WT in 62% (34/55) of the samples. The corresponding In-house PCR results were 25% (14/55) and 65% (36/55). In summary, the Panther Fusion assay demonstrated detection of low copy number of MRM and WT of MG. Among clinical samples substantial agreement between the Panther Fusion and In-house PCR results was observed. Integrating MG-analysis (TMA) and MRM-WT assay on the Panther platform could make MRM testing more readily available. However, the Panther Fusion had a lower success rate (82% vs 90%) for macrolide susceptibility testing, hence testing with a complementary method should be considered for samples where neither WT nor MRM MG are detectable.