P3.168 Evaluation of the point-of-care xpert® CT/NG and osom® trichomonas rapid tests against the anyplex™ii STI-7 detection assay

Abstract

IntroductionSyndromic management of sexually transmitted infections (STIs), as practised in most poorly resourced countries misses out asymptomatic infections. Affordable nucleic acid amplification tests (NAATs) are needed for accurate STI diagnosis and treatment.MethodsAs part of a cohort study assessing a diagnostic STI care model among young South African women presenting for syndromic care, we evaluated the clinic-based point-of-care (POC) tests Xpert CT/NG and OSOM Trichomonas Rapid Test against the laboratory-based Anyplex II STI-7, a multiplex real-time PCR assay which detects Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Trichomonas vaginalis (TV), M. genitalium (MG), M. hominis (MH), U. urealyticum (UU) and U. parvum (UP) in a single reaction. All positive and discordant results were confirmed with a third molecular assay, the FTD STD9.ResultsVaginal swabs taken from 247 women were assessed in parallel. 238 of 247 (96.4%) results were in agreement comparing Xpert and Anyplex. All nine discrepant results were positive for CT on Xpert but negative on Anyplex. FTD STD9 confirmed three positive and six negative results. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of Xpert for CT against the two assays was 100%, 97.1%, 86.0%, 100%, respectively; and for NG 100%, 99.6%, 92.3%, 100%. The sensitivity, specificity, PPV and NPV of OSOM for TV against the two assays was 77.8%, 100%, 100%, 99.2%. In addition to the CT, NG and TV detection, the Anyplex identified a prevalence of 4.8% MG, 33.5% MH, 19.1% UU and 51.4% UP in this population.ConclusionThe overall performance of Xpert CT/NG against laboratory-based assays was comparable. A lower PPV may lead to some overtreatment, however, in a high burden STI and HIV region, where STIs are often asymptomatic, the high sensitivity and specificity are reassuring. The widened spectrum of Anyplex targets highlights the high burden of Ureaplasma and Mycoplasma species in this setting, whose clinical significance need further exploration.

Multiplexed rapid technologies for sexually transmitted infections: a systematic review

“…15,18,34 Across numerous studies, study participants seeking regular screening for sexually transmitted infections, medical consultation, or a biological check-up, suspected of having a sexually transmitted infection, women seeking syndromic care, or sexually active women aged 14-49 years presenting with lower urinary tract infection symptoms were included. 20,22,24,25,[27][28][29][30][31]38 Many studies focused on key at-risk populations such as men who have sex with men, transgender populations, Aboriginal populations, people who inject drugs, women with at least two recent partners, female sex workers, and labourers who have paid for sex. 17,19,21,23,26,32,33,[35][36][37] Additional populations of interest included pregnant women, women who are infertile, and patients with genital ulcer disease (table 1).…”

“…Certain devices yielded 100•0% sensitivity with very high specificity, such as Aurora FLOW (Roche, Basel, Switzerland; pooled vaginal for female participants and urine [urethral], rectal, or throat for male participants), 30 GeneXpert CT/NG (Cepheid, Sunnyvale, CA, USA; vaginal and urine), 17,24 and Bio-Rad Dx CT/NG/MG (vaginal and endocervical for female participants and urine for male participants). 22…”

“…15,16,18,20,22,26,28,29,34 Moreover, certain high-throughput and low-throughput platforms consistently yielded high sensitivity and specificity for several sexually transmitted infections; these included the Anyplex II STI-7 Detection kit PCR, 15,18,20 AmpliSens PCR, 18,28 Bio-Rad Dx CT/NG/MG, 22,29 HIV/HCV/HBsAg Triplex, 34 STDFinder, 26 Siemens VERSANT kPCR, 16 and Cepheid's GeneXpert. 17,24,25,39,40 Among all immunochromatographic tests, the high performance of the SD Bioline HIV/Syphilis Duo Test stood out. 32,[35][36][37] In particular, the Anyplex II STI-7 Detection kit PCR, STDFinder, and AmpliSens PCR offer additional benefits in clinical care due to their ability to detect at least four sexually transmitted infections concurrently.…”

“…With respect to usefulness in diagnostic care, the majority of RNAAT platforms were used in laboratories. [15][16][17][18]20,21,[24][25][26][27][28][29][30]32 At or near the point of care, several investigators who led field-based studies expressed the clinical usefulness and high diagnostic accuracy of Cepheid's GeneXpert low-throughput RNAAT platform device for use near patients, parti cularly to diagnose gonorrhoeae and chlamydia. 17,24 Systematic review findings, including a 2014 evaluation done by the Pacific Northwest Evidence-based Practice Center, 39,40 further support this statement.…”

“…urine for female participants and urine for male participants; urine for female participants; and urine for male participants), 28 Anyplex II STI-7 Detection kit PCR (endocervical, urine, and urethral), 20 GeneXpert CT/NG (urine), 17 Siemens VERSANT kPCR (urine), 16 Bio-Rad Dx CT/NG/MG (pooled urine, vaginal, endocervical, and urethral), 22 and STDFinder (vaginal). 26 Additionally, several tests showed 100•0% sensitivity, including Anyplex II STI-7 Detection kit PCR (urine and endocervical), 18 GeneXpert CT/NG (vaginal), 24 Bio-Rad Dx CT/NG/MG (urogenital and anorectal), 29 and Seeplex PCR (Seegene, Seoul, South Korea; urine and endocervical). 18 Alternatively, Anyplex II STI-7 Detection kit PCR (rectal), 20 BD Max CT/GC/TV (Becton Dickinson, Sparks, MD, USA; urine for male participants), 31 and AmpliSens PCR (vaginal) had 100•0% specificity.…”