Introduction Infection of Neisseria gonorrhoeae in the pharynx (pharyngeal Ng) is associated with gonococcal transmission and development of antimicrobial resistance. We aimed to assess determinants for: (1) spontaneous clearance and (2) persistence after treatment of pharyngeal Ng.

Methods At the sexually transmitted infections clinic Amsterdam, females-at-risk and men who have sex with men are routinely screened for pharyngeal Ng using an RNA-based nucleic acid amplification test (NAAT; Aptima Combo 2). A test-of-cure (TOC) 7 days after treatment is suggested for positive cases.We retrospectively examined medical records of pharyngeal Ng patients (January 2012-August 2015). To evaluate spontaneous clearance (sub-study 1), we included patients who had follow-up NAAT result prior to antibiotic treatment. To evaluate persistence after treatment (sub-study 2), we included patients who received 500 mg ceftriaxone intramuscular injection and returned for a TOC 7–28 days after treatment.

Results In sub-study 1, 1266 cases (median time between first consultation and follow-up of 10 days [interquartile range/IQR 7–14]) were included; spontaneous clearance was found in 139 (11.0%) and was associated with age >45 years (vs 16–24 years) (aOR=1.96 [95% CI 1.06–3.60]), and with time from first consultation to follow-up (aOR=1.08 [1.06–1.10], per extra day). In sub-study 2, 781 cases (median time between first treatment and TOC of 8 days [IQR 7–12]) were included; persistence after treatment was found in 36 (4.6%), and was less likely among patients who received ceftriaxone in combination with other antibiotics (vs monotherapy) (aOR=0.36 [0.12–1.04]), and with longer time from treatment to TOC (aOR=0.74 [0.60–0.90], per extra day). In TOC 15–28 days after treatment, only 1/105 cases (1.0%) persisted.

Conclusion Spontaneous clearance of pharyngeal Ng is associated with later time of follow-up and higher age. Combining ceftriaxone with other antibiotics leads to faster clearance. TOC for pharyngeal Ng 7 days after treatment may be too soon.

Support: This study was funded by Excellence Scholarship Program (Beasiswa Unggulan), Ministry of Research, Technology and Higher Education, Republic of Indonesia and Public Health Service of Amsterdam, the Netherlands