Utility of Pooled Urine Specimens for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae in Men Attending Public Sexually Transmitted Infection Clinics in Mumbai, India, by PCR

Abstract

Pooling urogenital specimens for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae by nucleic acid amplification tests is an attractive alternative to individual testing. As pooling can reduce the costs of testing as well as labor, it has been advocated for use in resource-poor settings. However, it has neither been widely adopted nor evaluated for use in developing countries. We evaluated the practical use of pooling first-catch urine (FCU) specimens for the detection of C. trachomatis and N. gonorrhoeae from 690 men in Mumbai, India, by PCR. FCU, urethral smears, and swabs were collected from men seen at two sexually transmitted infection (STI) clinics. All laboratory testing was done at the Lokmanya Tilak General Hospital. Gram stain smears and culture isolation for N. gonorrhoeae were performed. Each FCU was tested individually and in pools using the Roche Amplicor PCR for C. trachomatis and N. gonorrhoeae with an internal control for inhibition. Specimen pools consisted of aliquots from five consecutively processed FCUs combined into an amplification tube. An optical density reading of >0.20 indicated a pool for which subsequent testing of individual samples was required. Prevalence by PCR on single specimens was 2.2% (15/690) for C. trachomatis and 5.4% (37/690) for N. gonorrhoeae. Compared to individual FCU results, pooling for C. trachomatis and N. gonorrhoeae had an overall sensitivity of 96.1% (50/52). Specificity was 96.5% (83/86) in that three pools required single testing that failed to identify a positive specimen. Pooling missed two positive specimens, decreased the inhibition rate, and saved 50.3% of reagent costs. In this resource-limited setting, the use of pooling to detect C. trachomatis and N. gonorrhoeae by PCR proved to be a simple, accurate, and cost-effective procedure compared to individual testing.

Socio‐cultural, psychosexual and biomedical factors associated with genital symptoms experienced by men in rural India

“…For example, an abnormal urethral discharge and burning or painful micturition (dysuria) in men are considered suggestive of gonorrhoea and chlamydia (Adler 1998), and syndromic guidelines are used to manage symptomatic men in India (Hawkes & Santhya 2002). However, recent studies of Indian men have reported low prevalences of gonorrhoea and chlamydia (Joyee et al 2004;Lindan et al 2005), in conjunction with a high burden of reported symptoms (International Institute for Population Sciences 2001). This suggests that the syndromic guidelines for the treatment of STIs may have low specificity and costeffectiveness among symptomatic Indian men in comparison with other developing countries where the prevalence of STIs is higher (Gilson et al 1997).…”

Testing Pooled Sputum with Xpert MTB/RIF for Diagnosis of Pulmonary Tuberculosis To Increase Affordability in Low-Income Countries

“…One approach that can reduce costs is to pool (put together) specimens from several patients and test them using a single test (6,7). If a pool tests positive, then each specimen is tested individually to detect the positive sample(s), whereas if the pooled specimens test negative, all individuals are considered infection free (6,7).…”

“…One approach that can reduce costs is to pool (put together) specimens from several patients and test them using a single test (6,7). If a pool tests positive, then each specimen is tested individually to detect the positive sample(s), whereas if the pooled specimens test negative, all individuals are considered infection free (6,7). A pooling strategy appears to be cost-effective and accurate when NAATs are used to screen blood for HIV (8) and blood-borne hepatitis viruses (9), detect Chlamydia trachomatis and Neisseria gonorrhoeae in urine specimens (7), and identify influenza virus in nasopharyngeal swab samples (4).…”

“…If a pool tests positive, then each specimen is tested individually to detect the positive sample(s), whereas if the pooled specimens test negative, all individuals are considered infection free (6,7). A pooling strategy appears to be cost-effective and accurate when NAATs are used to screen blood for HIV (8) and blood-borne hepatitis viruses (9), detect Chlamydia trachomatis and Neisseria gonorrhoeae in urine specimens (7), and identify influenza virus in nasopharyngeal swab samples (4). A potential disadvantage of pooled testing, however, is a decrease in test sensitivity through dilution of positive specimens beyond an assay limit of detection (10).…”

Cost-Effective Pooling of DNA from Nasopharyngeal Swab Samples for Large-Scale Detection of Bacteria by Real-Time PCR

“…This idea was suggested by Dorfman in 1943 (6) and has been used for the serological diagnosis of infectious diseases. Pooling samples is also an efficient way to screen for the nucleic acids of viruses, bacteria, or parasites (4,5,(7)(8)(9)(10)(11)(12)(13)(14)(15). However, pooling can decrease the sensitivity of assays due to the dilution of the samples, which is problematic in clinical diagnostics (16).…”