Pharyngeal Chlamydia and gonorrhea: a hidden problem

In this study we assessed the prevalence and predictors of pharyngeal infections due to Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) in a cohort of patients attending an STI Clinic. From January 2016 to September 2018, 893 patients attending the STI Clinic of St Orsola-Malpighi Hospital (Bologna, Italy) and reporting unprotected oral sex were enrolled. A pharyngeal swab for the molecular detection of CT and NG was collected from each patient. Positive CT samples were further genotyped by an omp1 gene PCR. A total of 134 cases of gonorrhea (15%) and 34 chlamydial infections (3.8%) were detected in the pharyngeal site, with no significant differences between males (all men who have sex with men [MSM]) and females. More than 90% of the infections were completely asymptomatic, suggesting that symptoms were not predictors of a pharyngeal infection ( P = 0.7). On the contrary, a history of sexual contacts with a partner positive for CT and/or NG ( P < 0.0001), HIV positivity ( P = 0.01), and the presence of concurrent genital and/or rectal infections ( P < 0.0001) were significantly associated with CT/NG pharyngeal infections. Pharyngeal lymphogranuloma venereum cases were rare (prevalence: 0.4%), asymptomatic, and only found in MSM. Better knowledge about pharyngeal CT/NG infections could help to set up effective strategies for their prevention.