Individualised treatment of sexually transmitted infections by rapid molecular assays

Abstract

Antimicrobial resistance (AMR) is a major problem in the field of sexually transmitted infections (STIs), where escalating levels have coincided with a surge in infections. The individualised treatment of STIs by rapid molecular ‘resistance’ assays is a new approach to patient management that has developed through understanding of the mechanisms of resistance, combined with nucleic acid amplification diagnostics. Mycoplasma genitalium provides an excellent example of this approach because of a restricted repertoire of effective antibiotics, and resistance mediated by single nucleotide polymorphisms. Detection of one of five M. genitalium 23S rRNA gene mutations is highly predictive of treatment failure with macrolides; employing this diagnostically yields >95% cure with azithromycin. Detection of fluoroquinolone resistance mutations in parC (especially affecting serine 83) and gyrA is predicted to have a similar diagnostic value and is currently being evaluated. This work is underpinned by high quality resistance data, emphasising the importance of ongoing surveillance. Despite some limitations, individualised treatment has demonstrated value in antimicrobial stewardship, extending the use of current therapies despite substantial levels of resistance, reducing prescription of ineffective treatments and sparing last-resort antibiotics.