LAUSR

Background Neisseria gonorrhoeae (NG) has developed resistance to most antibiotics, making it increasingly difficult to treat. Molecular methods have been used to predict antimicrobial susceptibility based on the gyrA codon serine 91 and the mosaic XXXIV allele on the penicillin-binding protein 2 (penA) gene using Roche Cobas and APTIMA clinical specimens. We aimed to determine if the same methods could be successfully used on remnant NG-positive Cepheid Xpert® specimens. Methods We tested NG-positive pharyngeal, rectal, and vaginal/urine specimens from adolescents aged 14–24 years. We extracted 100uL DNA from each sample using the Roche® MagNA Pure. The Roche LightCycler® 480 was used to genotype gyrA and penA in a multiplex PCR using high resolution melt curve analysis. The fluorescent labels of the detection probes for the penA mosaic XXXIV target (Cyanine-5 dye) differed from that of gyrA (LightCycler® 640 probe) so that both genes could be detected simultaneously at various wavelengths. We used isolates with previously confirmed presence of the NG mutant gyrA, NG wild type gyrA, and mosaic penA XXXIV allele for internal controls. Results Of the clinical specimens, 62% (38/61) were successfully genotyped. Urine specimens were most likely to be genotyped (5/6, 83%) followed by rectal (19/26, 73%), pharyngeal (12/24, 50%), and vaginal specimens (2/5, 40%). Of the 38 genotyped specimen, 8 had the penA XXXIV allele (2/26 rectal, 6/24 pharyngeal) and 16 had a mutated gyrA (10/26 rectal, 3/24 pharyngeal, 2/6 urethral, 1/5 vaginal). Of the 8 penA XXXIV positive specimens, 6 were gyrA indeterminate, 1 was gyrA wild type, and 1 was gyrA mutant. Of the 30 specimens without the penA XXXIV mosaic allele, 15 were gyrA wild type and 15 were gyrA mutant. Conclusion Genotyping specific NG genes from Cepheid Xpert® clinical specimens was feasible. Our study was limited by its small sample size and lack of concurrent antimicrobial testing. Disclosure No significant relationships.