Gentamicin Alone Is Inadequate to Eradicate Neisseria Gonorrhoeae From the Pharynx
Lindley A Barbee1,2, Olusegun O Soge3, Jennifer Morgan2
1Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington, USA.
Background:
Centers for Disease Control and Prevention (CDC) guidelines recommend 240 mg gentamicin plus 2 g azithromycin for the treatment of gonorrhea in cephalosporin-allergic patients. The efficacy of gentamicin alone in the treatment of pharyngeal gonorrhea is uncertain.
Methods:
Between September 2018 and March 2019, we enrolled men who have sex with men with nucleic acid amplification test-diagnosed pharyngeal gonorrhea in a single-arm, unblinded clinical trial. Men received a single 360-mg intramuscular dose of gentamicin and underwent test of cure by culture 4-7 days later. The study measured creatinine at enrollment and test of cure, serum gentamicin concentration postdose to establish peak concentration (Cmax), and standard antimicrobial minimum inhibitory concentrations (MICs) 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 participants; assuming gentamicin was 80% efficacious, the trial would establish a 95% confidence interval (CI) of 66%-90%. We planned interim analyses at n = 10 and n = 25.
Results:
The study was stopped early due to poor efficacy. Of 13 enrolled men, 10 were evaluable, and only 2 (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 percentage change was +5.2% (range, -6.7% to 21.3%). Six (46%) participants experienced headache, all deemed unrelated to treatment.
Conclusions:
Gentamicin alone failed to eradicate Neisseria gonorrhoeae from the pharynx. Clinicians should use caution when treating gonorrhea with the CDC's current alternative regimen (gentamicin 240 mg plus azithromycin 2 g) given increases in azithromycin resistance and gentamicin's poor efficacy at the pharynx.
Clinical Trials Registration:
NCT03632109.
Insights
Gentamicin alone is not effective for treating pharyngeal gonorrhea, failing to eradicate the bacteria in most participants. Clinicians should exercise caution with current alternative regimens due to rising antibiotic resistance.
Area of Science:
- Infectious Diseases
- Microbiology
- Clinical Pharmacology
Background:
- Centers for Disease Control and Prevention (CDC) guidelines suggest gentamicin plus azithromycin for gonorrhea in penicillin-allergic patients.
- The efficacy of gentamicin monotherapy for pharyngeal gonorrhea remains uncertain.
Purpose of the Study:
- To evaluate the efficacy of gentamicin alone for treating pharyngeal gonorrhea.
- To establish a point estimate for gentamicin's efficacy in this specific patient population.
Main Methods:
- A single-arm, unblinded clinical trial enrolled men with diagnosed pharyngeal gonorrhea.
- Participants received a single 360-mg intramuscular dose of gentamicin.
- Cure was assessed by culture 4-7 days post-treatment; renal function and gentamicin concentrations were monitored.
Main Results:
- The study was halted early due to low efficacy; only 2 of 10 evaluable participants (20%) were cured.
- Efficacy was not linked to gentamicin peak concentration (Cmax) or minimum inhibitory concentrations (MICs).
- No renal insufficiency was observed; headaches were the most common adverse event.
Conclusions:
- Gentamicin monotherapy failed to eradicate Neisseria gonorrhoeae from the pharynx.
- Caution is advised for the CDC's alternative regimen (gentamicin/azithromycin) due to azithromycin resistance and gentamicin's poor pharyngeal efficacy.
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