Verification of clinical samples, positive in AMPLICOR Neisseria gonorrhoeae polymerase chain reaction, by 16S rRNA and gyrA compared with culture

Abstract

We compared 956 samples for AMPLICOR Neisseria gonorrhoeae polymerase chain reaction (PCR) (Roche) with species verification using the 16S rRNA gene to verification using gyrA gene. Control was the culture method. The gyrA verification uses pyrosequencing of the quinolone resistance-determining region of gyrA. Of 52 samples with optical density >/=0.2 in PCR, 27 were negative in culture, two samples from pharynx were false negative in culture and four samples from pharynx were false positives in verification with 16S rRNA. Twenty-five samples showed growth of gonococci, 18 of the corresponding PCR samples were verified by both methods; three urine samples were positive only in gyrA ; and one pharynx specimen was positive only in 16S rRNA. Three samples were lost. We conclude that AMPLICOR N. gonorrhoeae PCR with verification in gyrA gene can be considered as a diagnostic tool in populations with low prevalence of gonorrhoea and that pharynx specimens should not be analysed by PCR.

Pyrosequencing of the DNA gyrase gene in Neisseria species: effective indicator of ciprofloxacin resistance in Neisseria gonorrhoeae

“…Despite the fact that a few ciprofloxacin‐resistant N. gonorrhoeae strains without alterations in the QRDR of the gyrA have been reported (15–17), the present study supports previous studies (6–9) of pyrosequencing of the QRDR in the gyrA gene as an effective molecular method to indicate resistance to ciprofloxacin in N. gonorrhoeae. However, the method is useful for N. gonorrhoeae and presumably for N. meningitidis , but not for other Neisseria spp.…”

“…Consequently, samples that give no PCR product can be verified as non‐ N. gonorrhoeae. In a previous study Airell et al (6) showed that out of 24 N. gonorrhoeae culture‐negative pharynx samples, 16 were positive in AMPLICOR N. gonorrhoeae PCR (Roche Diagnostics). N. gonorrhoeae species verification using the 16S rRNA gene was negative in 14 of these samples and in all 16 with verification with the gyrA gene.…”

“…The AMPLICOR N. gonorrhoeae PCR (Roche Diagnostics, Indianapolis, IN, USA) targets the putative cytosine DNA methyltransferase gene. A PCR targeting the 16S rRNA gene has been recommended for confirmation (8), but we found it suboptimal for this purpose (6). Our previous results showed that the QRDR of the gyrA could be used as an indicator of ciprofloxacin resistance in N. gonorrhoeae and possibly for species verification of N. gonorrhoeae (6, 8, 9).…”

“…A PCR targeting the 16S rRNA gene has been recommended for confirmation (8), but we found it suboptimal for this purpose (6). Our previous results showed that the QRDR of the gyrA could be used as an indicator of ciprofloxacin resistance in N. gonorrhoeae and possibly for species verification of N. gonorrhoeae (6, 8, 9). In addition, the QRDR of the gyrA seems to be an effective indicator of ciprofloxacin resistance in N. meningitidis (10–12).…”

Selective Testing Criteria for Gonorrhea among Young Women Screened for Chlamydial Infection: Contribution of Race and Geographic Prevalence

“…Even highly specific assays may have unacceptably low positive predictive values in such settings. Although a validation study in Washington State (0.5% prevalence) found that only 3% of specimens positive for gonorrhea by APTIMA COMBO 2 assay were potentially falsely positive [14], false-positive N. gonorrhoeae test results have been a problem with the COBAS AMPLICOR CT/NG assay (Roche Molecular Systems), and confirmatory testing is required in lowprevalence populations [15,[30][31][32]. Adopting selective testing criteria could reduce the risk of false-positive results by increasing the prevalence of infection among those tested.…”