TABLE 3.
Performance of the real-time PCR platform in characterizing the collection of 193 N. gonorrhoeae isolates alone and combined with the 39 N. gonorrhoeae control strainsg
| Phenotypic target | Target sequence(s) |
N. gonorrhoeae isolates collected during 1989–2014 (n = 193) |
All N. gonorrhoeae strains (n = 232), including 39 controls |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Test result | No. of isolatesa | No. of isolates with AST resultb |
Sensitivityd (%) (95% CI) | Specificityd (%) (95% CI) | Test result | No. of strainsa,e | No. of isolates with AST resultb |
Sensitivityd (%) (95% CI) | Specificityd (%) (95% CI) | ||||
| S | R | S | R | ||||||||||
| Species identification | opa and/or porA | Positive | 193 | NA | NA | 100 (97–100) | NA | Positivee | 232 | NA | NA | 100 (98–100)e | 100 (82–100)e |
| Negative | — | Negativee | 19 | ||||||||||
| CRO | penA Gly545Ser and/or penA Ala501 | Positive | 16 | 16 | — | NA | 92 (87–95) | Positive | 26 | 24 | 2 | 100 (16–100) | 90 (85–93) |
| Negative | 177 | 177 | — | Negative | 206 | 206 | — | ||||||
| CFX | penA Gly545Ser and/or penA Ala501 | Positive | 16 | 9 | 7 | 100 (47–100) | 95 (91–98) | Positive | 26 | 14 | 12 | 92 (64–100) | 94 (90–96) |
| Negative | 177 | 177 | — | Negative | 206 | 205 | 1f | ||||||
| AZMc | 23S rRNA A2059G or 23S rRNA C2611T | Positive | — | — | — | NA | 100 (97–100) | Positive | 4 | — | 4 | 100 (40–100) | 100 (98–100) |
| Negative | 193 | 193 | — | Negative | 228 | 228 | — | ||||||
| CIP | gyrA Ser91Phe | Positive | 58 | — | 58 | 100 (91–100) | 100 (96–100) | Positive | 83 | — | 83 | 100 (96–100) | 100 (98–100) |
| Negative | 135 | 135 | — | Negative | 149 | 149 | — | ||||||
| SPC | rpsE Thr24Pro or 16S rRNA C1192T | Positive | — | — | — | NA | 100 (97–100) | Positive | 3 | — | 3 | 100 (29–100) | 100 (98–100) |
| Negative | 193 | 193 | — | Negative | 229 | 229 | — | ||||||
Numbers are based on the results of the multiplex real-time PCR platform.
AST was categorized based on EUCAST criteria with the exception of AZM (see below).
AZM resistance was defined as an MIC of >2 μg/ml.
Sensitivity was the probability that an isolate categorized as being resistant was identified as positive by real-time PCR; specificity was the probability that an isolate categorized as being sensitive was identified as negative by real-time PCR.
For the evaluation of “species identification,” we also included the 19 nongonococcal Neisseria species strains.
Strain WHO L (nonmosaic penA gene with an additional mutation encoding the Ala501Val amino acid substitution).
AST, antimicrobial susceptibility testing by Etest; R, resistant; S, susceptible; CI, confidence interval; —, zero; NA, not applicable.