Nucleic acid amplification testing (NAAT) was found to have an increased sensitivity and specificity for detecting extragenital Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections compared with standard culture methods, according to results of a study published in the Journal of Clinical Microbiology.

Between May 2018 and August 2019, researchers conducted a study that compared the effectiveness of 3 types of NAATs (m2000, MAX, and Cobas) for diagnosing CT and NG infections. They enrolled a total of 2390 patients aged 14 years and older from 8 outpatient clinics who reported an extragenital exposure, with or without subsequent symptoms, within the past 30 days. Each patient provided 3 anorectal and 3 oropharyngeal swab specimens for analysis via the 3 types of NAATs. To evaluate the performance of each NAAT, the researchers compared the individual results of all 3 NAATs with the composite result.

Among a total of 2390 patients included in the final analysis, 52.5% were men, 46.4% were women, and 1.1% identified as transgender. Overall, results of all 3 NAATs showed that 1.2% (n=28) and 5.8% (n=139) of patients were positive for CT infection at the oropharynx and the anorectal site, respectively, with positive results equally distributed among men, women, and transgender persons. Results of NAAT also showed that 4.0% (n=96) and 4.2% (n=100) of patients were positive for NG infection at the oropharynx and anorectal sites, respectively. Of note, no differences in assay performance were observed among the 3 types of NAATs in terms of patients’ sex or symptom status.


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The researchers noted that all 3 types of NAATs detected CT and NG infections in both oropharyngeal and anorectal specimens with an estimated specificity of greater than 98.9%.Sensitivity estimates for CT infections detected in anorectal specimens were 81.0%, 94.6%, and 95.1% for the m2000, MAX, and Cobas assays, respectively, and 82.8%, 100%, and 100% for oropharyngeal specimens, respectively. Sensitivity estimates for NG infections detected in anorectal specimens using the m2000, MAX, and Cobas assays were 85.9%, 91.5%, and 99.0%, respectively, and 74.0%, 88.4% and 100% for oropharyngeal specimens, respectively. Although analysis of oropharyngeal swab specimens showed no differences in CT infection rates between men who have sex with men (MSM) vs men who have sex with women (MSW), NG infection rates were increased among MSM vs MSW (6.5% vs 3.0%; P = .04).

On analysis of recent data, the researchers found that some extragenital infections may fail to respond to treatment more often than genital infections. In addition, oropharyngeal NG infections may increase the risk for gonococcal antimicrobial resistance, and sexually transmitted rectal infections may increase the risk for HIV infection and transmission.

According to the researchers, “the self-collection of [anorectal and oropharyngeal] specimens will need to be evaluated to support testing that is acceptable to patients and can be performed in a variety of settings.” The researchers concluded that they, “hope that data from this study will facilitate the [FDA] approval process to make anorectal and oropharyngeal CT/NG testing more widely available.”

Disclosure: Some author(s) declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Van Der Pol B, Chernesky M, Gaydos CA, et al. Multicenter comparison of nucleic acid amplification tests for the diagnosis of rectal and oropharyngeal Chlamydia trachomatis and Neisseria gonorrhoeae infection. J Clin Microbiol. Published online November 3, 2021. doi: 10.1128/JCM.01363-21