Evaluation of TIB Molbiol LightMix® assays for detection of Mycoplasma genitalium and key resistance mutations for macrolides and fluoroquinolones.

The LightMix® Modular Mycoplasma Macrolide and LightMix® Modular parC Fluoroquinolone Resistance assays (TIB Molbiol) were evaluated using sequential M. genitalium positive (n = 125) and negative (n = 93) clinical samples. Results were compared to the results of an established commercial assay (ResistancePlus MG assay, SpeeDx Pty Ltd) or Sanger sequencing (for parC). Detection of M. genitalium by the TIB Molbiol assay had a high agreement with the reference assay, with a positive % agreement (PPA) of 97.6 (95% CI: 93.1 to 99.5) and negative % agreement (NPA) of 95.7 (95% CI: 89.5 to 98.8). From 105 positive samples, macrolide resistance detection had a PPA of 100% (95% CI:93.7-100), NPA of 81.3% (95% CI: 67.4-91.1). For detection of fluroquinolone resistance mutation G248T/S83I or "other mutation" in the quinolone resistance determinant region, from 95 samples there was 100% (95%CI: 86.3-100) sensitivity and 100% (95% CI: 94.5-100) specificity. The understanding of the basis for fluoroquinolone treatment failure is still developing; it is therefore important to use the output of parC-based resistance assays with caution to avoid the inappropriate use of antibiotic therapies, especially considering the limited number of alternative treatments.