Use of Nucleic Acid Amplification Testing for Diagnosis of Extragenital Sexually Transmitted Infections

Abstract

Nucleic acid amplification testing (NAAT) is the preferred method to detect Chlamydia trachomatis and Neisseria gonorrhoeae, but no commercial tests are cleared by the U.S. Food and Drug Administration for use with extragenital swab samples. This study evaluated the performance of the Gen-Probe Aptima Combo2 assay (Aptima) and the Cepheid Xpert CT/NG assay (Xpert) to detect C. trachomatis and N. gonorrhoeae in rectal and pharyngeal samples from 224 men and 175 women reporting a history of anal receptive sexual intercourse. Discordant results between the NAATs were repeated using the assays APTIMA CT or APTIMA GC, which target alternate primers, as the confirmatory tests. C. trachomatis was detected from 59 rectal swabs and 8 pharyngeal samples, with 97.7% and 99.5% agreement between the two test systems, respectively. For C. trachomatis, Xpert was 95% sensitive (95% CI, 86 to 99%) and Aptima was 92% sensitive (95% CI, 81 to 97%) from rectal swabs, while both systems were 100% sensitive from pharyngeal samples. N. gonorrhoeae was detected from 30 rectal and 40 pharyngeal samples, with 99.5% and 97.5% agreement between the two test systems. The sensitivity of Xpert for N. gonorrhoeae from rectal swabs was 100% (95% CI, 88 to 100%) versus 93% (95% CI, 78 to 99%) for Aptima. From pharyngeal swab samples, Xpert was 98% sensitive (95% CI, 87 to 99.9%) versus 93% (95% CI, 80 to 98%) for Aptima. For C. trachomatis, neither system was Ͼ95% sensitive from the rectum, though both were Ͼ99.5% specific. For N. gonorrhoeae, Xpert had higher sensitivity than Aptima, but with more false positives from pharyngeal samples.

Meta-analysis of the Cepheid Xpert® CT/NG assay for extragenital detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections

“…Our search yielded a total of eight publications, 4,20-24,28,29 five [20][21][22][23][24] of which met our inclusion criteria. We excluded three studies because they were not evaluation studies.…”

“…Most studies evaluating extragenital testing performance for CT and NG detection by the Xpert CT/NG show high per cent agreement with comparison assays; however, because of the limited sample sizes of CT-and NG-positive cases, the precision around the positive per cent agreement is low. [20][21][22][23][24] Therefore, we aimed to combine data from all published studies of the performance of extragenital testing with Xpert CT/NG to better assess positive per cent agreement.…”

Evaluation of the Diagnostic Efficacy of Xpert CT/NG for Chlamydia trachomatis and Neisseria gonorrhoeae

“…Meanwhile, the result of NG analysis in sample type showed that I 2 values were lower than 50%, indicating low heterogeneity. In terms of gender, I 2 values of specificity in “female” were slightly higher than 50%, while I 2 values of “male” were lower than 50%, indicating low heterogeneity in “female,” but not in “male.” After in-depth study of these fourteen studies, it was believed that the reasons for the heterogeneity might be the following: (1) the specimens collected were either degraded or poorly mixed in the study [ 24 ], (2) the improper behavior of the patients when collecting the sample resulted in the incomplete specimens [ 28 ], and (3) before collecting vaginal specimens, female patients underwent vaginal cleansing [ 25 ]. The sensitivity and specificity of CT and NG in sample type were both greater than 0.9, and the specificity of NG was 1.…”

<p>Simultaneous detection of eleven sexually transmitted agents using multiplexed PCR coupled with MALDI-TOF analysis</p>

“…Routine screening for pathogens associated with STIs on an annual basis is recommended for all pregnant women, all sexually active females <25 years of age, and at-risk MSM. 5,31 To date, nucleic acid amplification tests (NAATs) are accepted worldwide as an important method for screening causative agents of STIs with several approved commercial molecular panels available. [32][33][34][35] In addition, several emerging nucleic acid amplification platforms combined with fully and partially automated instrumentation are available for targeting multiple microorganisms in a single test reaction.…”