Background Trichomonas vaginalis is the world's most common treatable sexually transmissible infection. Currently, wet mount microscopy and syndromic management based on vaginal discharge are the most widely used methods for diagnosing and treating trichomoniasis in resource-constrained settings. Wet mount microscopy requires equipment and trained technicians, who are in short supply. We examined the diagnostic accuracy of the OSOM Trichomonas Rapid Test for detecting T. vaginalis vaginal infection among women in Mysore, India.
Methods: During July 2009-August 2010, 450 sexually active women over 18 years seeking care at an urban reproductive health clinic were enrolled in the study. Clinician-collected vaginal swabs were evaluated for trichomonads using wet mount microscopy, InPouch culture and the OSOM test.
Results: Of the 418 samples included in the analyses, culture detected 68 (16.3%) positive samples, wet mount microscopy detected 56 of the culture-positive samples and four false positive samples. The OSOM test detected 60 of the culture-positive samples plus two false positive cases. Using the composite reference standard (CRS), defined as wet mount- or culture-positive, the sensitivities of wet mount, the OSOM test and culture were 83.3%, 86.1% and 94.4%, respectively. The positive and negative predictive values of the OSOM test were 100% and 97.1% respectively. The Cohen's kappa agreement between the OSOM test and the CRS was excellent (κ=0.94).
Conclusion: The OSOM test has high sensitivity, excellent specificity, and excellent positive and negative predictive value compared to a CRS. This simple test can improve screening and diagnosis of T. vaginalis infection in resource-constrained settings where microscopy and culture are unavailable.