Simultaneous Detection of Mycoplasma Genitalium and Mutations Associated with Macrolide Resistance Has the Potential to Improve Patient Management

Background: The 2015 CDC STD treatment guidelines highlighted Mycoplasma genitalium (Mg) as an emerging issue based on increasing evidence linking it with several diseases like urethritis, PID and cervicitis.Treatment of M. genitalium (Mg) infection with azithromycin, is routinely utilized in clinical practice. However, widespread use has been associated with the emergence of macrolide resistance and ineffective cure rates. A new qPCR assay, PlexPCR™ M. genitalium ResistancePlus™ kit, has been developed to simultaneously identify Mg and 5 mutations in the 23S rRNA gene (positions 2058 and 2059 (E. colinumbering)) associated with macrolide resistance. This study evaluates incorporating the assay into a diagnostic algorithm to direct faster and more appropriate clinical management and reduce the spread of antibiotic resistance. 

Methods: 1087 consecutive urogenital samples from symptomatic and asymptomatic patients were evaluated prospectively with the PlexPCR M. genitalium ResistancePlus kit which employs novel PlexPrime (amplifies mutants specifically) and PlexZyme (superior multiplexing) technology. This was compared to an in-house test for Mg detection and sequencing of Mg positives to determine 23S rRNA mutation status.

Results: The prevalence of Mg was 6.0% and in the Mg positive samples 23S rRNA mutation prevalence was 63.1%. The PlexPCR M. genitalium ResistancePlus assay showed very high clinical performance compared to the reference methods with sensitivity and specificity for Mg detection of 98.5% and 100.0%, and 23S rRNA mutation detection of 92.7% and 95.7%  respectively. The limit of detection (LOD)  was 10 - 15 copies  for each mutant when LOD study was performed on synthetic template and no cross-reactivity of related organisms was seen.

Conclusions: The PlexPCR M. genitalium ResistancePlus kit demonstrated excellent clinical performance for the simultaneous detection of Mg and assessment of macrolide resistance. This test has the potential to be used in screening of Mg detection and macrolide resistance to allow more appropriate clinical management.