Urine Test May Help Diagnose Chlamydia in Men

Laurie Barclay, MD

July 29, 2009

July 28, 2009 — A simple urine test giving rapid results could help diagnose Chlamydia trachomatis infection in men, according to the results of a prospective cohort study reported in the July 29 issue of the BMJ. Although this infection is typically asymptomatic and remains undiagnosed, it is the most common sexually transmitted bacterial infection in the United States and the United Kingdom. If not treated, chlamydia may cause pelvic inflammatory disease, infertility, and ectopic pregnancy in women, as well as infertility in both sexes.

"We have evaluated the performance of a new Chlamydia Rapid Test, developed at the diagnostics development unit of the University of Cambridge," write Elpidio-Cesar Nadala, from Diagnostics for the Real World (Europe), Cambridge Science Park, United Kingdom, and colleagues. "The assay is used in conjunction with a collection device for male urine...specifically designed to collect the first voided urine that contains a higher organism load, and test results are available in less than an hour. This assay was developed to aid in the diagnosis of chlamydial infection and to provide a screening tool for the detection of such infection among young sexually active males."

The goal of this study was to assess the performance of Chlamydia Rapid Test with first-void male urine samples as a potential tool for the diagnosis and screening of chlamydial infection in men. The study cohort consisted of 1211 men aged 16 to 73 years attending a sexual health center for young people (site 1) or a genitourinary medicine clinic (site 2) in the United Kingdom.

The sensitivity, specificity, and positive and negative predictive value of the Chlamydia Rapid Test were compared with those of the polymerase chain reaction assay, and the association between the visual signal of the Chlamydia Rapid Test and organism load was also determined.

For the polymerase chain reaction assay, detection rates for C trachomatis infection were 4.4% (20/454) at site 1 and 11.9% (90/757) at site 2. For the Chlamydia Rapid Test vs polymerase chain reaction assay, the resolved sensitivity was 82.6% (90/109), specificity was 98.5% (1085/1102), positive predictive value was 84.1% (90/107), and negative predictive value was 98.3% (1085/1104).

The organism load in first-void urine samples that were positive for chlamydia correlated significantly with the visual signal of the Chlamydia Rapid Test (r, 0.7897; P < .001) and ranged from 7.28 × 102 to 6.93 × 106 plasmids/mL.

"The performance of the new Chlamydia Rapid Test with first void male urine samples indicates that it would be an effective diagnostic tool for chlamydial infection in men," the study authors write. "The availability of test results within an hour allows for immediate treatment and contact tracing, potentially reducing the risks for persistent infection and onward transmission. The test could also provide a simple and reliable alternative to nucleic acid amplification assays for testing of male urine in chlamydial screening programmes in high prevalence settings."

Limitations of this study include the low prevalence of chlamydia at site 1 and the inability to control for inhibitory substances potentially present in some urine specimens.

"Future studies should focus on determining whether the widespread use of the Chlamydia Rapid Test in screening young men for chlamydial infection in high prevalence settings can help prevent sequelae among their female sexual partners," the study authors conclude. "In addition, more studies are warranted to verify whether the Chlamydia Rapid Test would reassure young men that testing can be quick, simple, and non-invasive, and this might increase uptake. The rapid test might also be used to confirm the chlamydia status in men with symptomatic non-gonococcal urethritis at the point of care, thus allowing more efficient contact tracing and focusing the health promotion resources on these individuals at the time of testing."

The Wellcome Trust supported this study, with additional support from the National Institute for Health Research Cambridge Biomedical Research Centre. Three of the study authors, the University of Cambridge, and the Wellcome Trust are equity holders in Diagnostics for the Real World, which markets the rapid test technologies developed at the University of Cambridge.

BMJ. 2009;339:b2655.