Background:
In the United States, an estimated 5 to 7 million new Trichomonas vaginalis (TV) infections occur each year. TV infection causes vaginitis in women and urethritis in men, but is frequently asymptomatic and may cause pre-term labor, pelvic inflammatory disease, infertility, and increased incidence of HIV transmission.

Objective:
To assess the performance of culture and nucleic acid amplification tests (NAATs) for the detection of TV.

Method:
Adult vaginal swab specimens were cultured in Diamond's medium or the InPouchTV culture system. 0.5 mL of culture medium was added to GEN-PROBE APTIMA Swab Transport. Specimens were tested using GEN-PROBE APTIMA General Purpose Reagents and RUO Transcription-Mediated Amplification (TMA) TV oligonucleotides. Specimens were also tested using a LabCorp-developed real time PCR assay and a alternate TMA assay. The specimens' identifying information and culture results were masked prior to NAT analysis. In addition, 200 urine specimens were randomly collected from 100 adults and 100 children, masked, and tested by the TMA and Alt TMA assays.

Result:
Of the 922 vaginal swab specimens tested, 659 (71.5%) were negative in all tests and 81 (8.8%) were positive by all four methods. Sixty-one specimens (6.6%) were negative by culture but positive by TMA, Alt TMA and PCR assays, leading to 260 total specimens (28.2%) that were positive using the 3 NAATs. Nineteen specimens (2.1%) were negative by culture and PCR but positive by the TMA and Alt TMA assays. Of 100 urine specimens from adult subjects, 2 were positive by the TMA and Alt TMA assays. Of 100 urine specimens from children, none were positive by the TMA and Alt TMA assays.

Conclusion:
These results demonstrate GEN-PROBE TMA NAATs and the LabCorp PCR NAAT detect significantly more TV infections in vaginal swab-derived samples than does testing by culture.

Implications:
Culture underestimates the prevalence of T.vaginalis in the US population.