Introduction Previous studies reported that in a considerable proportion of pharyngeal gonorrhoea cases treated with extended-spectrum cephalosporins, the infection remains detectable after several weeks. We examined the occurrence of prolonged pharyngeal gonorrhoea infections after treatment with ceftriaxone at a sexually transmitted infection (STI) outpatient clinic in Amsterdam.

Methods A retrospective cohort study was conducted based on routine electronic medical records at the STI clinic of the Public Health Service (GGD) of Amsterdam. Eligible for inclusion were: adults diagnosed with pharyngeal gonorrhoea between January 2012 and July 2013, who were treated with ceftriaxone (500 mg IM), and who returned for a test of cure (TOC) between 7 and 21 days after treatment.

Definitive diagnosis of gonorrhoea was based on Gen-Probe Aptima-Combo 2 Assay™ using Tigris DTS™ system. Some patients also received additional antibiotics with ceftriaxone.

Information on patients’ characteristics and clinical history were available, but data on sexual re-exposure after treatment were not.

Results In the study period, 880 pharyngeal gonorrhoea cases were diagnosed; 290 cases (32.9%) returned for a TOC visit and were eligible (255 males and 35 females, median age 34 and 25 years, respectively). In 17 cases (5.9%) N. gonorrhoeae infection was detected again. Prolonged infection was not associated with gender (p = 0.49) or age (p = 0.87), but appeared to be associated with sex work (OR = 3.24 [95% CI 0.83–12.45], p = 0.07). Prolonged infection was significantly more common among those who were treated with ceftriaxone only vs a combined-regimen (OR = 4.07, [95% CI 0.90–18.39]; p = 0.048).

Conclusion Prolonged pharyngeal gonorrhoea infection after appropriate treatment was not uncommon, and was more often observed in those who were treated with ceftriaxone only. This could be the result of re-infection after treatment or of treatment failure possibly due to poor tissue penetration. Treatment failure due to antimicrobial resistance seems unlikely.

Disclosure of interest The study is fully funded by Public Health Service (GGD) of Amsterdam, The Netherlands. The authors declare that there is no conflict of interest.