Pharyngeal gonococcal infection and the sensitivity of oral gargle samples in comparison to self-collected throat swabs for the detection of N. gonorrhoeae in persons in Tyrol, Austria.

Abstract

Asymptomatic pharyngeal gonorrhoea could play an important role in transmission and should be screened for in persons at risk. We investigated the sensitivity of oral gargle samples to detect N. gonorrhoea and describe the frequency of infection by anatomical site. From June 2021 to July 2022 persons diagnosed with gonorrhoea in the STI/HIV department were asked to provide self-collected specimens for single-site testing by NAAT from throat (by gargling and swabbing), anorectum, and first-void urine. 104 episodes of gonorrhoea were analysed in 88 individuals. The median age was 33years, 85 persons (96.5%) were male. The pharynx was the most common site of infection (71 cases, 68.2%); in 26 persons (25.0%) it was the only site of infection. Anorectal infection was detected in 65 cases (62.5%) and urogenital infection in 25 cases (24.0%). In 46 cases (44.2%) infection was detected in more than one anatomical site. Gargling was less sensitive than throat swabbing to detect pharyngeal infection (85.9% versus 97.2%, p = .038), but was preferred by patients. Only 4 of 71 pharyngeal infections (5.6%) were symptomatic; anorectal and urogenital infections were symptomatic in 12.3% and 76.0% of cases, respectively. Culture recovery of N.gonorrhoeae was only possible in 15.8% of throat swabs, but was successful in 61.9% of anorectal and 84.2% of urogenital samples. Asymptomatic pharyngeal gonorrhoea is common. Gargle samples should be used only as alternative specimens with inferior sensitivity compared to throat swab samples.