Background:
The 2002 CDC guidelines recommend confirmatory testing for positive N. gonorrhoeae (GC) nucleic acid amplified tests (NAAT) if positive predictive values are <90%. Approaches for confirming a positive test include repeating the original test on the original specimen, and testing the original specimen with a different test format or target.

Objective:
To evaluate both strategies of confirmation on GC positive NAAT specimens detected by the APTIMA Combo- 2 (AC2, Gen-Probe, Inc.) assay.

Method:
Swabs and first catch urine specimens from symptomatic and asymptomatic men and women were tested by AC2, which detects both C. trachomatis and GC in a single test. The original positive GC specimens were repeat tested by AC2. Then, the original specimens were tested by the APTIMA GC Assay (AGC), which detects only GC. This test targets rRNA sequences different from AC2.

Result:
There were 220 original GC positives detected with AC2. Of these, 75 were male and 145 were female. We found 215 (97.7%) confirmed by repeat AC2 testing GC (1/5 that failed had low rlu readings (&#61603;500,000). AGC confirmed 214 (97.3%). Using both methods, 215 (97.7%) of the GC positives were confirmed.

Conclusion:
GC positives obtained by the COMBO 2 assays are confirmed to a high degree by either repeat testing or use of the Gen-Probe alternate amp assay.

Implications:
Our results suggest that confirmatory testing is not necessary for GC positive AC2 specimens.