Trichomonas vaginalis : an audit of clinical practice and the demography of infected patients at three London genitourinary medicine clinics

Patient demographics

In total 38,774 patients were seen between the three clinics during the audit period. The overall average demographic of female patients was 68.9% white and 11.7% African/Caribbean. Eighty-nine of patients were diagnosed with T. vaginalis, of which 96% (n = 85) were female and the mean age was 33 years old; 40.4% of these patients described themselves as white, 38.2% as Afro-Caribbean, 12.4% as mixed background, 1.1% as Indian and 7.9% as other or not recorded.

All patients received first line treatment with metronidazole 400 mg twice a day for five days or 2 g stat dose. No patients were referred following positive cytology results.

Seventy-eight percent of patients returned for a Test of Cure (TOC) of which five patients (6%) had a positive result. Contact tracing was performed in 87% of patients with 56% of these verifying one contact had been treated for T. vaginalis in the last four weeks.

Demographics

There was a 0.23% positivity rate of T. vaginalis in this cohort of patients which is lower compared to another study performed in a clinic in north England (0.8% positivity) despite London clinics presuming to have a greater prevalence. ⁴ This is likely, in part, to be due to the fact that a large proportion of our patient cohort is men who have sex with men. In resource-limited countries, the rates are higher and a recent study in Peru has shown the prevalence to be 0.3% in men, 4.9% in women and 7.9% in sex workers. ⁵

Globally, the infection is found more commonly in the black African/Caribbean population,^2,6 a finding supported by a pilot study amongst female students in London. ⁷ Our audit demonstrates a comparable number of T. vaginalis cases amongst white (40.4%) and African/Caribbean groups (38.2%), but proportionally the three clinics see a higher number of white female patients (68.9%) compared to African/Caribbean female patients (11.7%).

Investigation results

These results show an 81% sensitivity rate for wet microscopy compared to culture; this compares favourably to the UK average of 70%. ³ In a quarter of the patients, the microscopy or liquid medium culture investigations were negative and thus performing both was necessary (Table 1). Culturing T. vaginalis remains the gold standard investigation, with nucleic acid amplification tests (NAAT) awaited, but not yet readily available in our unit.

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Table 1.

Investigations: wet slide microscopy and liquid medium culture.

Investigations and results	Patients, %
Positive wet microscopy and positive liquid medium culture	70 (n = 62)
Positive wet microscopy and negative liquid medium culture	10 (n = 9)
Positive wet microscopy and no liquid medium culture results found	1 (n = 1)
Negative wet microscopy and positive liquid medium culture	17 (n = 15)
Wet microscopy not performed and liquid medium culture negative (found to be T. vaginalis positive at GP and referred to GUM clinic)	2 (n = 2)

There were a small number of patients (2%) who did not receive a positive result, but were included in the study as their general practitioner (GP) had positively identified T. vaginalis from high vaginal swabs and referred them to the GUM clinic after starting treatment with metronidazole.

Auditable outcomes

All patients met treatment targets (100% received metronidazole). The TOC attendance rate (78%) falls below the audit target of 100%, 6% of whom had a positive result; patients with poor compliance or non-treated partners were excluded. The 6% TOC positivity rate is consistent with the known 5% resistance of T. vaginalis to first line metronidazole treatment. ⁸ Three patients received a second course of metronidazole and two patients required tinidazole and/or acetarsol pessaries.

Eighty-seven percent of patients underwent contact tracing, the remaining patients left the clinic prior to meeting health advisers. Fifty-six percent of patients verified one contact had been treated in the last month, falling below the BASHH 60% audit target. On attempting to identify the reasons for this, patient case notes were reviewed and commonly the patients had informed partners, but not maintained further contact with partners to confirm if they had received treatment for the infection. To improve clinical standards, a teaching session for staff will be organised to raise awareness regarding the importance of performing and documenting partner notification, verifying whether contacts were treated and stressing to patients the importance of TOC, contacting patients who leave clinic prior to contact tracing. The use of NAAT testing will also be reviewed. A re-audit is planned once the action plan is implemented.