Introduction Both women and men who have sex with men (MSM) report frequent receptive oral sex, but there are no FDA approved tests for detection of Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) from pharyngeal swabs. The objective of this study was to evaluate the number of pharyngeal GC and CT infections, and to assess the sensitivity of GC culture.
Methods Women (n = 172) and MSM (n = 222) reporting a lifetime history of both receptive oral and anal sex completed a structured questionnaire and clinicians collected swab samples from the pharynx and anorectum. Vaginal swabs were obtained from women and urine samples from men. Testing for CT and GC was performed using Cepheid Xpert CT/NG (Xpert) and Gen-Probe Aptima (AC2). True positives were defined if both AC2 and Xpert were positive, if GC culture was positive, or if either AC2 or Xpert were positive and confirmatory tests APTIMA CT or APTIMA GC were positive.
Results Identification of GC and/or CT at any site (pharyngeal, rectal or genitourinary) occurred in 78/222 (35%) males and 25/172 (14.5%) of females. Only 8 (2%) of pharyngeal swab samples were positive for CT, while 4 women (2.3%) and 37 (16.7%) men tested positive for pharyngeal GC based on NAAT. GC culture of the pharynx was performed for 373 of participants in the study, and was positive in 13 (3.5%), for a sensitivity of 32% for culture vs NAAT. Overall, 17/55 (31%) of the total GC infections in men would have been missed without NAAT pharyngeal testing.
Conclusion Men who report a lifetime history of receptive oral intercourse have high rates of pharyngeal GC, most of which will remain undetected unless NAAT is used. The frequency of pharyngeal infection due to CT is low even among people having high overall rates of infection.
Disclosure of interest Reagents for CT/GC testing were provided for by Cepheid and Hologic.