The tampon test for trichomoniasis: a comparison between conventional methods and a polymerase chain reaction for Trichomonas vaginalis in women.

OBJECTIVES

Trichomonas vaginalis is the most common STD worldwide and the infection has been linked with an increased risk of HIV transmission. We present a detailed comparison between conventional collection and testing methods and the polymerase chain reaction (PCR) tampon test for T vaginalis.

METHODS

Women were tested for the presence of T vaginalis by PCR analysis of a tampon specimen and by conventional methods which included one or more of the following: culture and microscopy from a high vaginal swab (HVS) or endocervical swab (ECS), and microscopy of a Papanicolaou (Pap) smear.

RESULTS

T vaginalis was detected in 51/590 (8.6%) conventional tests and 93/590 (15.8%) tampon specimens. Retesting of all tampon PCR positive specimens confirmed 89/93 (95.7%) tests. Using the tampon PCR as the reference, the sensitivities of the different conventional sampling and testing methods for the detection of T vaginalis were 8.3% (5/60) for ECS microscopy or culture, 31% (13/42) for HVS microscopy or culture, 52.8% (19/36) for HVS directly inoculated into Trichomonas medium and 59.4% (38/64) for Pap smear.

CONCLUSIONS

No conventional test in the remote setting has comparable sensitivity to PCR. The Pap smear is the next most sensitive, but requires a speculum examination. The use of PCR will allow inclusion of T vaginalis into STD screening programmes in both developed (lower prevalence) and developing (higher prevalence) countries.