Evaluation of the ResistancePlus® MG FleXible assay for the detection of wild-type and 23S rRNA-mutated Mycoplasma genitalium

Background Antibiotic resistance in Mycoplasma genitalium (MG) is rising globally and resistance-guided diagnostics can facilitate targeted and timely treatment. Methods The ResistancePlus® MG FleXible (RPMG Flex) assay for the detection of MG and macrolide-resistance mediating mutations (MRMM) was evaluated for analytical sensitivity, specificity, reproducibility, and inhibition in the presence of interfering substances by simulating MG negative, pooled urine and swab matrices with MG cultures. Furthermore, the clinical sensitivity of the assay was evaluated and compared with a reference real-time PCR assay. Results 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. Conclusions 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 when 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 MG infections.