Microscopy outperformed in a comparison of five methods for detecting Trichomonas vaginalis in symptomatic women

Abstract

In the UK, despite its low sensitivity, wet mount microscopy is often the only method of detecting Trichomonas vaginalis infection. A study was conducted in symptomatic women to compare the performance of five methods for detecting T. vaginalis: an in-house polymerase chain reaction (PCR); Aptima T. vaginalis kit; OSOM ®Trichomonas Rapid Test; culture and microscopy. Symptomatic women underwent routine testing; microscopy and further swabs were taken for molecular testing, OSOM and culture. A true positive was defined as a sample that was positive for T. vaginalis by two or more different methods. Two hundred and forty-six women were recruited: 24 patients were positive for T. vaginalis by two or more different methods. Of these 24 patients, 21 patients were detected by real-time PCR (sensitivity 88%); 22 patients were detected by the Aptima T. vaginalis kit (sensitivity 92%); 22 patients were detected by OSOM (sensitivity 92%); nine were detected by wet mount microscopy (sensitivity 38%); and 21 were detected by culture (sensitivity 88%). Two patients were positive by just one method and were not considered true positives. All the other detection methods had a sensitivity to detect T. vaginalis that was significantly greater than wet mount microscopy, highlighting the number of cases that are routinely missed even in symptomatic women if microscopy is the only diagnostic method available.

Combined Testing for Chlamydia, Gonorrhea, and Trichomonas by Use of the BD Max CT/GC/TV Assay with Genitourinary Specimen Types

“…In this study, as in other evaluations of trichomonas culture sensitivity (18,24), there was a slight benefit to performing NAATs (Table 4); however, this is based on 5 days of reading the InPouch and is, thus, slow, labor-intensive, and requires highly skilled microscopists. Further, the lack of a standard that includes NAATs is known to inflate the sensitivity estimates of culture, and thus the marginal difference in sensitivity would likely expand to a larger difference if a composite infection standard (CIS) based on multiple NAATs had been possible during this trial.…”

Direct Diagnosis of <b><i>Trichomonas vaginalis</i></b> Infection on Archived Pap Smears Using Nested PCR

“…Several investigations revealed successfully amplified DNA specimens extracted from cytological Pap-stained smears. Most of them demonstrated that the PCR method is a useful complementary technique for Pap-stained cellular samples [20,21]. In contrast, Chen et al [22] reported that PCR amplification from archival Pap-stained smears was unsuccessful, and they stated that the PCR was possibly inhibited by hematoxylin and aluminum sulfate.…”

“…However, we believe that a number of cases were misdiagnosed because of the presence of Trichomonas -like atypical cervical cells [15]. Nathan et al [21] showed the number of trichomoniasis cases that are routinely missed even in symptomatic women if microscopy is the only diagnostic method available. Hence, our PCR method could be considered as a valuable alternative technique to rule out etiological agents of STI other than T. vaginalis in the laboratory.…”

Clinical and Laboratory Testing for Trichomonas vaginalis Infection

“…In multiple studies, the use of this test has improved case finding significantly compared to the number of cases found by only microscopy. In studies comparing the OSOM assay with nucleic acid amplification tests (NAATs), the POC test performed quite well, with sensitivity similar to that of NAATs (Ͼ80% compared to NAATs at Ͼ90%) (24,25). The only drawback to this test is that it can only be used for women and cannot be bundled with POC chlamydia/gonorrhea screening.…”

“…While motile trichomonads are very distinctive if observed microscopically, the organism load required in order to capture sufficient organisms for visualization is unknown. Comparison with newer diagnostic assays suggests that wet preparation microscopy is only 40 to 60% sensitive, even among symptomatic women (24). However, observation of motile trichomonads is highly specific and thus is very useful for determining a course of treatment.…”