A comparison of the sensitivity of the InPouch TV, Diamond's, and Trichosel media for detection of Trichomonas vaginalis

Abstract

Objective: This study compared the ability of three culture media (InPouch TV, Diamond's, and Trichosel) to support the growth of clinical isolates of Trichomonas vaginalis and their relative sensitivity for detection of the organism. Methods: The majority of the clinical isolates were obtained from two San Francisco Bay Area clinics. T vaginalis was subcultured in 4 ml of one of the InPouch, Diamond's, or Trichosel media for 24-48 hours before evaluation. Twenty isolates were initially cultured in the InPouch test, 13 with Diamond's, and 10 with Trichosel. A haemocytometer was used to measure the initial concentrations of the organisms. Then serial dilutions were made in saline to yield approximately 2.0 x 1045 2.0 x 103, and 2.0 x 102 motile T vaginalis per ml. A 30 μl inoculum from each dilution was transferred into 4 ml aliquots of the three media (387 individual tests, 43 x 3 dilutions x 3 media). Microscopic examinations for viable trichomonads were made at 24, 48, and 96 hours. Microscopy was through the pouch wall for the InPouch medium, and through a cover slipped slide with one drop of Diamond's and Trichosel media. Results: At 24 hours, the InPouch demonstrated 84/129 positive, Diamond's 23/129, and Trichosel 18/129. At 48 hours, an accumulative positive rate for the InPouch was 98/129, for Diamond's 55/129, and Trichosel 47/129. At 96 hours the total positives for each test were 112/129 for the InPouch, 78/129 for Diamond's, and 74/129 for Trichosel. Conclusions: The InPouch TV test was significantly more sensitive than either Diamond's or Trichosel (at 0.01 level of significance, P(InPouch) > P(Diamond's); P(InPouch) > P(Trichosel) on all three dilutions at 24, 48, and 96 hours). This increased sensitivity was the result of either a reduced generation time or the larger volume of media examined microscopically.