Introduction The aim of the study was to evaluate the clinical performances of the Aptima Mycoplasma genitalium CE-IVD assay (AMG, Hologic) for the detection of M. genitalium in clinical male and female samples in comparison with the in-house real-time PCR (qPCR) assay routinely used in our laboratory. The Aptima assay uses target capture, transcription-mediated amplification (TMA), and hybridization protection to detect the M. genitalium 16S rRNA.
Methods A total of 1431 clinical specimens obtained from 1235 patients were prospectively enrolled from February to June 2016 at the Bacteriology Department of Bordeaux University Hospital (France). For the AMG assay, various specimens collected in the appropriate APTIMA medium were processed according to the manufacturer’s instructions on the Panther system (Hologic). DNA extracts were obtained using the MagNA Pure 96 DNA and viral NA small Volume Kit on the MagNA Pure 96TM instrument (Roche Diagnostics). The in-house M. genitalium qPCR assay targeting the MgPa adhesin gene was performed on the cobas z480 analyzer (Roche Diagnostics). Additional RUO M. genitalium TMA assays, MGAlt1 and MGAlt2, and the CE-marked SpeeDx ResistancePlusTM MG assay were performed on the blinded discordant specimens to determine a definitive M. genitalium infection status. All the confirmed M. genitalium-positive specimens were tested for macrolide resistance using three comparative assays: the in-house FRET qPCR assay, the SpeeDx ResistancePlusTM MG assay and the nested reverse-transcription PCR sequencing assay.
Results The comparison of the AMG assay with the in-house qPCR result showed a moderate correlation, with a kappa value of 0.69. The TMA assay had a very good clinical sensitivity (100%) and specificity (99.33%) for M. genitalium detection across all specimen types tested. Its sensitivity was significantly higher than that of the in-house qPCR, 100% versus 61.33%. The prevalence of M. genitalium infection was 5.90% (72/1220 patients) and the prevalence of macrolide resistance-associated mutation was 5.47% (4/73).
Conclusion The Aptima Mycoplasma genitalium assay performed on the fully automated Panther system is a very sensitive and specific method for detection of M. genitalium in clinical specimens. On the Panther platform this assay can be easily combined with the assay for chlamydia and gonorrhoea detection from the same sample.