Rapid Assay Revives Ciprofloxacin Use for Gonorrhea

Ricki Lewis, PhD

June 02, 2017

A DNA-based assay quickly identifies gonorrhoea infections susceptible to the antibiotic ciprofloxacin and minimizes use of ceftriaxone in a regular clinic setting, according to results published in the May issue of Clinical Infectious Diseases.

In 2007, the Centers for Disease Control and Prevention stopped recommending use of ciprofloxacin to treat gonococcal infections because of growing multidrug resistance. However, about 80% of the infections in the United States currently remain susceptible to the antibiotic.

In the current study, Lao-Tzu Allan-Blitz, a medical student at the David Geffen School of Medicine at the University of California, Los Angeles (UCLA), and colleagues analyzed the effect of a test that identifies infections susceptible to ciprofloxacin. The test detects a single-base mutation (Ser91) in the gyrase A (gyrA) gene of Neisseria gonorrhoeae that renders the bacterium resistant to ciprofloxacin. In cases lacking that mutation, ciprofloxacin remains effective.  

The laboratory-developed test, which uses freely available methods and reagents, was put into clinical use in November 2015 in the UCLA Health system. Before implementation, clinicians were trained on the use of the test and treatment recommendations based on test results.

The researchers compared ciprofloxacin or ceftriaxone prescriptions for gonorrhea from January 2015 through July 2016, comparing the periods before and after implementation. The study included treatment for 283 infections among 251 patients treated at UCLA facilities.

Of all the cases, 113 (39.9%) were treated empirically on the same day as specimen collection: 58 of 130 (44.6%) cases before implementation and 55 of 153 (35.9%) after (P = .14).

Among those treated after implementation, genotyping was successful for 121 (68.8%) of the 176 infections, and 72 of those (59.5%) were susceptible to ciprofloxacin. In other words, fewer than half of the infections genotyped required treatment with ceftriaxone.

Moreover, genotyping seems to have shifted drug choice. Among infections treated nonempirically, 68 of 72 (94.4%) patients received ceftriaxone before implementation of genotyping, compared with 77 of 98 (78.6%) after genotyping began (P = .004).

The authors note that the mean time to treatment did not significantly differ among the cases treated nonempirically before and after genotyping, at 5.5 days vs 4.7 days, respectively.

Starting in May 2016, electronic alerts were sent to clinicians with the genotyping results, which increased use of the results. Of 35 cases infected with wild-type bacteria and treated empirically, the use of ciprofloxacin increased from 3 of 24 (12.5%) cases in the first 7 months of genotyping (before reminders) to 9 of 11 (81.8%) cases in the final 2 months after introduction of the reminders (P < .001).

"Reintroduction of antibiotics previously thought to be ineffective is a novel approach that may reduce the continued emergence of resistance, made possible by rapid molecular methods for targeted therapy," the researchers write.

Limitations of the study include participants from a single healthcare system, no consideration of clinical outcomes, lack of randomization, and use of a molecular assay that might not be available everywhere.

The authors have disclosed no relevant financial relationships.

Clin Infect Dis. 2017;64:1268-1270. Abstract

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