Ciprofloxacin May be Efficacious in Treating Wild-Type Gyrase A Genotype Neisseria gonorrhoeae Infections

Dear Editor

We read with great interest the article by Chesson et al. which illustrated the possible economic losses that may be averted by slowing the emergence of ceftriaxone resistant Neisseria gonorrhoeae infections [1]. As the threat of untreatable Neisseria gonorrhoeae infection increases [2], rapid molecular assays for the timely prediction of antimicrobial susceptibility are increasingly being utilized to target antimicrobial therapy [3]. A recent modeling study demonstrated the theoretical delay in the emergence of multidrug-resistant Neisseria gonorrhoeae with the use of such rapid molecular assays [4]. The University of California, Los Angeles Health System has implemented a rapid molecular assay for the determination of mutation in the gyrase A (gyrA) gene of Neisseria gonorrhoeae [5, 6]. The absence of mutation in that gene has been shown to reliably predict susceptibility to ciprofloxacin [7]. As suggested by the article by Chesson et al. the use of ciprofloxacin may spare ceftriaxone, and thus reduce the emergence of ceftriaxone resistant Neisseria gonorrhoeae infections [8].

Ciprofloxacin has been shown to be >99% effective among infections with phenotypic susceptibility [9], however one concern regarding the current utility of ciprofloxacin in the treatment of Neisseria gonorrhoeae infections is that there have been no studies evaluating patient outcomes among those with wild-type (non-mutated) gyrA genotype Neisseria gonorrhoeae infection. We have collected outcome data from participants with wild-type Neisseria gonorrhoeae infections treated with ciprofloxacin at the University of California, Los Angeles Health System. We completed a retrospective review of 25 patient records between June 2016 and September 2017 with a repeat Neisseria gonorrhoeae test performed between 7-90 days after single dose ciprofloxacin 500 mg oral treatment of the initial infection. Of those 25 participants, 100% (95% CI 83% – 100%) had a negative test of cure. The anatomic sites of infection included rectal (n=7), pharyngeal (n=7), urethral (n=7), and unspecified genital swabs (n=4). There was no difference in repeat test results by time to repeat test 7–21 days (100%) vs. 22–90 days (100%) (p-value>0.1).

Those preliminary results provide promising evidence of the efficacy of ciprofloxacin for the treatment of wild-type gyrA genotype Neisseria gonorrhoeae infections. There are additional costs to gyrA genotyping and genotype-based therapy compared with recommended empiric two-drug therapy with ceftriaxone and azithromycin [10]; however, in the light of the potential costs incurred by the emergence of ceftriaxone resistant infections as suggested by Chesson et al. we advocate for further implementation of the gyrA genotypic assay in other health systems for the promotion of targeted Neisseria gonorrhoeae therapy.