Aptima test effective in spotting Trichomonas vaginalis

By David Douglas

The Aptima Trichomonas vaginalis (TV) test from Gen-Probe detects more infections than does culture, but the low prevalence of the disease in the UK suggests that routine use may not be cost-effective, according to a new report.

Currently, UK guidelines advocate selective testing for TV infection, Dr. Emma Hathorn of University Hospitals Birmingham NHS Foundation Trust and colleagues write in Sexually Transmitted Infections, online August 29.

To investigate whether the APTIMA test, which has been approved in the U.S. and was recently licensed in the UK, might have a part to play, the researchers offered this nucleic acid amplification test to unselected patients presenting at an inner city sexual health clinic.

More than 3,500 patients were tested, of whom 72 women (3.6%) and 21 men (1.4%) were infected. The rate was significantly higher in black Caribbeans than in Caucasians (9.0% vs. 1.2% for women and 5.4% vs. 0.1% for men).

In fact, the researchers note that ethnicity has consistently been associated with TV infection and most of the infected participants were black Caribbean (56% of women and 76% of men).

Overall, culture and TV TMA results were in good agreement in women (98.5%). But in the 17 cases where the tests did not agree, the Aptima test detected 16 additional infections. This amounted to 38% more than culture in symptomatic women.

As well as being more sensitive than culture, say the researchers, the Aptima test offers quick turn around and could speed treatment and partner notification. This supports its use as the preferred test for TV diagnosis.

On the other hand, they add that because of the low general prevalence of TV, routine screening is "probably not justified."

Nevertheless, despite its expense compared to use of microscopy and culture, it "may have a role in screening high-risk populations who have an increased prevalence of asymptomatic TV infection."

Dr. Barbara Van Der Pol, who was not involved in the study but has done research in the field, said the test had shown "excellent performance."

"The authors did not provide information regarding the relative prevalence of other organisms (namely Chlamydia trachomatis and Neisseria gonorrhoeae) for which routine screening is provided," Dr. Van Der Pol, of the University of Alabama at Birmingham School of Medicine, told Reuters Health by email. "The recommendation to consider offering screening to women with known risk factors is appropriate and should perhaps be expanded to include women living in sub-populations with elevated risk for HIV. Given the increased risk of infection with HIV for women with T. vaginalis, and the (often) higher prevalence than N. gonorrhoeae, this is a particularly relevant public health concern."

Dr. Hathorn did not respond to requests for comments. Two of her co-authors reported financial ties to Gen-Probe.

SOURCE: http://bit.ly/1wZ4XuX

Sex Transm Infect 2014.

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