A multisite implementation of a real-time polymerase chain reaction assay to predict ciprofloxacin susceptibility in Neisseria gonorrhoeae

Abstract

There are no commercially available Food and Drug Administration–cleared rapid tests for Neisseria gonorrhoeae antimicrobial susceptibility testing. This study evaluated the performance of a laboratory-developed real-time polymerase chain reaction assay for genotyping the gyrA gene to determine antimicrobial susceptibility to ciprofloxacin. Validation and clinical performance of the gyrA assay were evaluated across 3 geographic locations (Los Angeles, San Francisco, Philadelphia). Following validation, clinical specimens were collected in Aptima Combo2® CT/NG transport medium from asymptomatic persons who tested positive for Neisseria gonorrhoeae and evaluated for assay percent reportable (i.e., proportion of N. gonorrhoeae–positive specimens that yielded a gyrA genotype). The percentage of gyrA genotyping results differed by laboratory and specimen type. The proportion of specimens that were reportable was best for urine/genital specimens (genotyped = 76.4% (95% confidence interval, 69.9–82%)) followed by rectal (genotyped = 67.2% (95% confidence interval, 63.4–70.6%)) and then pharyngeal specimens (genotyped = 36.1%, (95% confidence interval, 31.9–40.5%)). Overall, asymptomatic patients with N. gonorrhoeae yielded an interpretable genotype 57.2% (784/1370) of the time, of which 480 were wild-type gyrA, resulting in 61% (480/784) being potentially treatable with ciprofloxacin.