Gentamicin Alone Inadequate to Eradicate Neisseria Gonorrhoeae from the Pharynx.

CDC guidelines recommend 240 mg gentamicin plus 2g azithromycin for the treatment of gonorrhea in cephalosporin-allergic patients. The efficacy of gentamicin alone in the treatment of pharyngeal gonorrhea is uncertain.Between September 2018 - March 2019, we enrolled men who have sex with men (MSM) with NAAT-diagnosed pharyngeal gonorrhea in a single-arm, unblinded clinical trial. Men received a single 360mg intramuscular (IM) dose of gentamicin and underwent test-of-cure (TOC) by culture 4-7 days later. The study measured creatinine at enrollment and TOC, serum gentamicin concentration post-dose to establish peak concentration (Cmax), and standard antimicrobial minimal inhibitory concentrations (MIC) by agar dilution. The trial was designed to establish a point estimate for gentamicin's efficacy for pharyngeal gonorrhea. We planned to enroll 50 evaluable subjects; assuming gentamicin was 80% efficacious, the trial would establish a 95% confidence interval of 66%-90%. We planned interim analyses at n=10 and n=25.The study was stopped early due to poor efficacy. Of 13 enrolled men, 10 were evaluable, and only two (20%, 95%CI: 2.5% - 55.6%) were cured. Efficacy was not associated with gentamicin Cmax or MIC. No participants experienced renal insufficiency. The mean creatinine percent change was +5.2% (range: -6.7%, +21.3%). Six (46%) subjects experienced headache; all deemed unrelated to treatment.Gentamicin alone failed to eradicate N. gonorrhoeae from the pharynx. Clinicians should use caution when treating gonorrhea with CDC's current alternative regimen (gentamicin 240mg plus azithromycin 2g) given increases in azithromycin resistance and gentamicin's poor efficacy at the pharynx.