Literature reviews  >  Articles for review > Huppert et al. Use of an immunochormatographic assay... 

The OSOM Trichomonas Rapid Test performed better than wet mount and detected T. vaginalis in less time than culture.

Use of an immunochormatographic assay for rapid detection of Trichomonas vaginalis in vaginal specimens.
Huppert JS, Batteiger BE, Braslins P, Feldman JA, Hobbs MM, Sankey HZ, Sena AC, Wendel KA.
Journal of Clinical Microbiology 2005;43:684-87.
 
Summary:

Question

How well does the OSOM Trichomonas Rapid Test, a point-of-care diagnostic assay for trichomoniasis, perform compared to a composite reference standard for the detection of T. vaginalis in vaginal specimens from women?

Design

This article describes a prospective, multicenter, cross-sectional study to determine the performance of the OSOM Trichomonas Rapid Test compared to a composite reference standard of wet mount microscopy and culture for T. vaginalis detection in vaginal swabs and saline wet preparation from women.

Participants

Four hundred forty-nine sexually active women (mean age = 28 years, range = 18 to 61 years) presenting to any of seven sites with signs and symptoms of vaginosis or vaginitis (98%), or due to exposure to T. vaginalis through an infected partner (5%), or reporting two or more sexual partners within the last 30 days (22%) were tested. Seventy-six percent were African-America, 21% were Caucasian, and 4% were Hispanic.

Description of Tests and Diagnostic Standard

Three vaginal samples were collected from each woman in varying order. One swab was placed into a tube with 0.5 ml of saline and used within 10 min for wet mount microscopy according to standard protocols at each site (n = 449).Another swab was used to immediately inoculate an InPouch TV culture device (BioMed Diagnostics, San Jose, CA) according to the manufacturer's instructions. The culture was incubated for up to 5 days (n = 405).A third vaginal swab was placed into a dry tube. This specimen (n = 437) and residual saline used to prepare the wet mount (n = 447) were stored at –20^oC for up to 17 weeks then thawed and tested using the OSOM Trichomonas Rapid Test (Genzyme Diagnostics, Cambridge, MA) in the Genzyme laboratory by technicians blinded to the wet mount and culture results. The OSOM is a point-of-care assay for T. vaginalis that uses an immunochromatographic capillary flow (dipstick) technique employing two murine monoclonal antibodies, one immobilized on the surface of the dipstick and the other conjugated to particles and dried onto the dipstick. A swab that was placed into the residual saline used to prepare the wet mount and the vaginal swab were placed into tubes containing sample buffer, mixed, allowed to sit for 1 min, and removed. The dipstick was placed into the tube containing the buffer/sample mixture and the results were read at 10 min. A positive result was indicated by the presence of a blue test line and a red control line. A negative result was indicated by only a red control line. The result was invalid if no red line was visible.

Main Outcome Measures

The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the OSOM tests of the vaginal swab and wet mount saline and of wet mount microscopy were determined based on a composite reference standard (CRS) defined as positive if the patient had a positive result by either wet mount or culture.

Main Results

T. vaginalis was detected 105 (23.4%) ofthe 449 women by wet mount, culture, or both.The performances of the OSOM rapid test for vaginal swabs and wet mount saline and of wet mount microscopy for detection of T. vaginalis as determined by the CRS are shown in the table. The sensitivity of OSOM when used to test vaginal swabs was statistically higher than that of wet mount (P = 0.004). Among women with specimens tested by culture, wet mount, and rapid test, 97, 70, and 81, respectively, were positive. Of 19 women with specimens positive by culture on days 2 or 3, 8 and 1 were also positive by OSOM and wet mount, respectively. Specimens from 2 women that were not culture positive until day 4 or 5 were negative for both wet mount and the rapid test. Coinfection with C. trachomatis or N. gonorrhoeae did not affect the performance of the OSOM test.

Performance of wet mount and OSOM rapid test performed on vaginal swabs and wet mount saline for detection of T. vaginalis compared to a composite reference standard

Authors' Conclusions

In this population of women at high risk for STDs, and in a research setting with expert microscopists, the OSOM test was more sensitive than wet mount for detecting T. vaginalis. The OSOM test was easier to perform and faster than culture. The OSOM may be a useful adjunct test for wet mount negative subjects where culture is unavailable and useful for facilities without access to microscopes or incubators.

Source of funding: Genzyme Diagnostics

For correspondence: Jill S. Huppert, Division of Adolescent Medicine (ML 4000), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039.E-mail address: jill.huppert@cchmc.org

about SDI | newsletters | grants | publications | literature reviews

WHO Home - WHO Search - TDR Home - SDI Home - SDI Contact us
(c) WHO/OMS 2001