Assessment of Bacterial Sexually Transmitted Infections (STIs) Viability by Polymerase Chain Reaction (PCR) in Men Who Have Sex With Men

Screening for C. trachomatis and N. gonorrhoeae STIs at 3 anatomical sites, i.e. pharyngeal, urogenital and anal, is recommended every three to six months in MSM with high-risk sexual behaviors, using NAAT. A positive NAAT result defines the patient as infected, and the patient will receive antibiotic treatment. However, repeated use of antibiotics has led to the emergence of multi-drug resistant strains of M. genitalium, another STI agent, and N. gonorrhoeae, and to changes in the gut microbiota. One disadvantage of NAATs is that they amplify the nucleic acids of viable and dead bacteria. Thus, it is not possible to affirm that the patient has an "active" infection, defined by the presence of viable bacteria. Bacterial viability can be studied by real-time PCR (called V-PCR). This method combines the high sensitivity and specificity of PCR with the ability to exclude detection of nucleic acid remnants from non-viable bacteria. It does so by incorporating a sample pretreatment step with a membrane impermeable DNA intercalating dye prior to molecular analysis by blocking amplification of remnant DNA from non-viable bacteria. This allows the V-PCR analysis to detect DNA originating from intact (i.e. viable) bacteria. Using V-PCR, studies in women have shown that only half of the anorectal samples and one quarter of the pharyngeal samples positive for C. trachomatis contain viable bacteria.

The team proposes to investigate the presence of viable C. trachomatis, N. gonorrhoeae and M. genitalium bacteria by V-PCR in pharyngeal, urogenital and anal specimens from MSM detected as positive by NAAT for these bacteria.

The results of this work will allow us to assess whether all types of specimens tested in these patients contain viable bacteria, and if so, in what proportions.