Trichomonas vaginalis antigens in vaginal and urine specimens by immunochromatography, compared to culture and microscopy

Abstract

This study evaluated the immunochromatographic (IC) capillary flow technology for detection of T. vaginalis antigens in vaginal and urine specimens. The IC antigen-detection test and microscopy wet smears were assessed against the InPouch TV culture. Vaginal-swabs and first-voided urine specimens were obtained from 348 sexually active symptomatic or asymptomatic, > or =16 years old women. Nineteen samples (5%) were positive by culture (95%, CI 0.3-0.8). The IC test (vaginal-specimens) was more sensitive than the wet smears. IC sensitivity was 84% (95%CI, 0.68-1.01), specificity 98% (95%CI, 0.96-0.99), positive predictive value (PPV) 70% (95%CI, 0.51-0.88), negative predictive value (NPV) 99% (95%CI, 0.98-1), (positive likelihood ratio (+LR): 39.6, and negative likelihood ratio (-LR) 0.2. The IC test using urine as a substrate had less performance than both microscopy and IC test of vaginal specimens. Urine-IC sensitivity was 53% (95%CI, 0.30-0.75), specificity 99% (95% CI, 0.98-1.00), PPV 77% (95%CI, 0.54-1), NPV 97% (95%CI, 0.96-0.99), +LR: 57.7, and -LR: 0.5. Sensitivity of vaginal smear was 68% (95%CI, 0.48-0.89), specificity 100%, PPV 100% (95% CI, 1), NPV 98% (95% CI, 0.97-1), +LR>225, & -LR: 0.3. T. vaginalis was diagnosed in two wet urine samples, but not in smears. The IC antigen improved T. vaginalis diagnosis, especially in screening, rapid, or point-of-care test, but in urine was less reliable than with vaginal smear.