Background Accurate diagnosis of chlamydia and gonorrhoea infections followed by appropriate treatment are critical steps in preventing transmission and morbidity. Sex workers are a target population for lab-based screening. This study compared the performance of commercially available nucleic acid amplification tests (NAATs) to detect chlamydia and gonorrhoea infections among FEWs in Cambodia.
Methods In 2011, 2564 FEWs were recruited and consented into a national prevalence survey for sexually transmitted infections (STIs) in Cambodia. Two self-collected vaginal swab specimens were obtained from 2525 FEWs. One swab was placed in m2000 media for testing with m2000, and the other was placed in GeneLock media for testing with AC2 and GeneXpert. Specimens were tested for chlamydia and gonorrhoea with the Abbott m2000 and Aptima AC2 assays. Samples with discrepant results were tested with the Cepheid GeneXpert assay. The reference standard was defined as results from two of three assays being in agreement.
Results By reference standard, chlamydia and gonorrhoea were detected in 21.2% and 7.0% of samples respectively. The m2000 and AC2 assays detected chlamydia in 499 specimens, and discordant results were found in 127 specimens. When compared to the reference standard, the m2000 sensitivity and specificity for chlamydia was 99.1% and 95.8% respectively. The sensitivity and specificity of AC2 for chlamydia was 94.4% and 99.6%. Gonorrhea was detected by both assays in 134 specimens while 110 yielded discordant results. The m2000 was 97.7% and 97.3% sensitive and specific for gonorrhoea while sensitivity and specificity of AC2 was 78.0% and 99.9% respectively.
Conclusions Chlamydia and gonorrhoea are prevalent STIs among Cambodian FEWs. Both NAATs had high sensitivity and specificity for chlamydia, and high specificity for gonorrhoea, but the AC2 sensitivity for gonorrhoea was low. Given high sensitivity and specificity of the assays, cost and usability will be important factors for ongoing programmatic use.
- sexually transmitted infections
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