Evaluation of a rapid point-of-care test for the detection of gonococcal infection among female sex workers in Benin

Abstract

Objectives: To assess the validity of the PATH (Seattle, Washington, USA) GC-Check rapid test, a point-ofcare immunochromatographic strip test, in the detection of gonococcal infection among female sex workers (FSWs) in Benin. Methods: Women consulting consecutively at two FSW-dedicated clinics in Cotonou and Porto Novo (Benin) were recruited over three, 1-month periods between October 2003 and July 2004. After written informed consent, participants were administered a short interview and underwent a speculum examination where two cervical swabs were collected (in a subset of women, a vaginal swab was also collected). One cervical swab and the vaginal swab were immediately tested with the rapid test. The other cervical swab was frozen at -20˚C for at most four weeks and then transported to Québec (Canada), where it was tested with the Roche Amplicor CT/NG PCR assay. Samples positive for gonococcal infection were confirmed using a 16SrRNA PCR assay. Results: 1084 FSWs (median age 29 years) participated in the study, of whom 50 (4.6%) had a confirmed gonococcal infection. The sensitivity, specificity, positive and negative predictive values of the rapid test on cervical samples were 70.0% (95% confidence interval (CI) 55.4% to 82.1%), 97.2% (95% CI 96.0% to 98.1%), 54.7% and 98.5%, respectively. The sensitivity of the rapid test on vaginal swabs among 759 women (37 positives for gonococcal infection) was significantly lower than with the cervical swab (54.1%, p = 0.008), whereas the specificity was comparable (98.2%, p = 0.13). Conclusions: The PATH GC-Check test may be as efficient as a gold standard polymerase chain reaction (PCR) test for treating gonococcal infection when taking into account the proportion of women who do not return for their test results. In clinics serving populations with moderate prevalence of this infection, it could significantly reduce over-treatment compared to the syndromic approach.

Are we satisfied with the tools for the diagnosis of gonococcal infection in females?

“…11,17 In spite of their lower sensitivity, immunoassays, as rapid point-of-care tests, might outperform other standard tests in populations with high sexual activity, such as sexual workers and/or in those with low return rates in developing countries. 26 If treatment can be started at the initial visit, the possibility of onward transmission of N. gonorrhoeae can be minimized 7,18 Immunoassays are an easy-to-use method with rapid diagnosis, low cost and no requested microscopy, therefore, they seem more acceptable than other tools in developing countries. 11,17,18,20 …”

“…26 If treatment can be started at the initial visit, the possibility of onward transmission of N. gonorrhoeae can be minimized 7,18 Immunoassays are an easy-to-use method with rapid diagnosis, low cost and no requested microscopy, therefore, they seem more acceptable than other tools in developing countries. 11,17,18,20 …”

Schnelltest-Diagnostik sexuell übertragbarer Infektionen in niedrigschwelligen Einrichtungen

“…Vergleichbar zur Testung bei C. trachomatis existieren auch für Gonokokken eine Reihe von AntigenSchnelltests, die aber nur in wenigen Fäl-len in Studien evaluiert worden sind. Für drei untersuchte immunchromatographische Tests wurde eine Sensitivität zwischen 54 % und 94 % und eine Spezifität zwischen 89 % und 98 % beschrieben [48][49][50] Keine Verbesserungen sind in den letzten fünf Jahren bei den Antigen-Schnelltests für C. trachomatis und N. gonorrhoeae erreicht worden. Diese Tests können aufgrund mangelnder Sensitivität und Spezifität weiterhin nicht empfohlen werden.…”

Rapid point-of-care tests for HIV and sexually transmissible infection control in remote Australia: can they improve Aboriginal people's and Torres Strait Islanders' health

“…8 A few POC tests for detection of gonorrhoea have been evaluated with sensitivity estimates ranging from 53% to 94%. 9,10 New syphilis POC tests are now able to differentiate recent and past infection with high sensitivity and specificity estimates of >95%. 11 However, these tests are unable to provide the rapid plasma reagin titre required to track the serological response to treatment.…”