Background
Neisseria gonorrhoeae (NG) is the most common sexual transmission infection (STI) in MSM; the objective of our study is to analyze clinical and microbiological characteristics of NG infections in a cohort of MSM.
Methods
All diagnosed NG infections in MSM (on PrEP or PLHIV) at risk of STIs undergoing regular STI screening from October 2023 to September 2025 were analyzed. Cases without culture were excluded. STI screenings were performed by two samples (one for culture and one for PCR assay) from each site: pharyngeal, rectal, urethral/urine. Samples were transported to the Microbiology Service in Amies transport medium (Deltalab©) and inoculated onto Martin-Lewis agar (Biomerieux®). NG identification was performed using the Malditof system. Susceptibility testing of isolates was carried out using E-test strips following EUCAST recommendations. Real-time PCR was also performed using the automated Cobas 4800 system (Roche©NG/CT). Epidemiological and clinical data were collected. Statistical program: jamovi.
Results
Among the 617 NG infections with positive PCR assay, cultures were performed in 605 (98,0%) episodes, of which 467 were on PrEP, 132 PLHIV, and 6 MSM without PrEP. Mean age was 37.8 years (SD ±9,9). Cultures were positive in 162 cases (26.8%). By site: rectal 139 out of 405 (34,3%) positive PCR, pharyngeal 2 out of 155 (1,2%), and urethral/urine 17 out of 34 (50.0%) (p<0.001); 525 (86.7%) of the episodes were asymptomatic, and 85 (14.0%) episodes had concomitant STIs (Chlamydia 60 and syphilis 17). In 124 episodes, subjects were on doxycycline post-exposure prophylaxis (Doxy-PEP) and had fewer concomitant STIs (8.06 vs 15.5%, p<0.03). Positive cultures were not associated with symptoms, HIV infection, or concurrent STIs. However, symptoms were associated with concomitant STIs (23.5 vs 11.9% p<0,004). All isolates were sensitive to ceftriaxone, and 61.0% resistance to tetracycline: (Doxy-PEP vs no Doxy-PEP 73.8 vs 56.2%, p=0.047). No seroconversions occurred in subjects on PrEP during this period.
Conclusions
Most NG infections in MSM are asymptomatic. In this context, culture sensitivity is low, with higher recovery rates in rectal and urethral samples. All isolates were sensitive to ceftriaxone and almost half to tetracyclines. Subjects on Doxy-PEP have fewer concomitant STIs. The transmissibility of a positive PCR assay but negative-culture, especially pharyngeal, should be deeply investigated.