Pooled Pharyngeal, Rectal, and Urine Specimens for the Point-of-Care Detection of Chlamydia trachomatis and Neisseria gonorrhoeae by Lay Providers in Key Population-Led Health Services in Thailand

Abstract

Routine testing for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) in people with heightened risk is lacking in Thailand. This study aimed to assess the performance of the Cepheid Xpert CT/NG assay, conducted by key population (KP) lay providers, for CT and NG detection on single-site and pooled specimens from the pharynx, rectum, and urine. Between August and October 2019, 188 men who have sex with men and 11 transgender women were enrolled. Participants collected urine specimens while trained KP lay providers obtained pharyngeal and rectal swabs. Compared to single-site testing with the Abbott RealTime CT/NG assay by medical technologists, the Xpert assay missed one pharyngeal NG infection out of 199 single-site specimens, giving a 93.3% sensitivity for pharyngeal NG and one missed pharyngeal NG infection out of fifty pooled specimens, giving an 88.9% sensitivity for pharyngeal NG. There was no discrepancy between the two assays for CT detection. The Cohen's Kappa coefficient of pooled specimen testing by the Xpert was 0.93 for NG and 1 for CT when compared to single-site testing by Abbott. Implementing pooled specimen testing by KP lay providers can be a cost-saving strategy to enhance the uptake of CT/NG services for populations facing increased risk.

Keywords: Asia; CT/NG; Chlamydia trachomatis; Neisseria gonorrhoeae; Thailand; men who have sex with men; molecular diagnostics; point-of-care detection; pooled specimens; transgender women.

Figure 1

Flowchart for CT/NG specimen collection and testing procedures. CT, Chlamydia trachomatis; NG, Neisseria gonorrhoeae; * Pooled specimen preparation and subsequent testing were conducted using specimens derived from 50 PLHIV participants.