Assessment of Trichomoniasis
Key Point: Trichomoniasis is often asymptomatic in both men and women, making systematic screening essential in high-risk populations including Aboriginal and Torres Strait Islander communities.
Clinical Presentation
Women
- Vaginal discharge (frothy, yellow-green, malodorous) - 50-75% of cases
- Vulvar irritation, pruritus, or burning
- Dysuria and urinary frequency
- Dyspareunia
- Strawberry cervix (punctate haemorrhages) - pathognomonic but only 2% of cases
- Asymptomatic - up to 50% of infected women
Men
- Urethral discharge (usually scanty, clear/white)
- Dysuria
- Urethral irritation or tingling
- Post-void dribbling
- Asymptomatic - up to 90% of infected men
- Complications: epididymitis, prostatitis (rare)
Clinical Pearl: High index of suspicion required due to frequent asymptomatic presentation. Consider in all patients with urogenital symptoms and sexual risk factors.
Risk Factors
High-Risk Populations
- Multiple sexual partners or new sexual partner
- Previous STI history
- Aboriginal and Torres Strait Islander people
- Young people aged 15-29 years
- Sex workers
- Men who have sex with women (MSW) in high-prevalence areas
- Partners of infected individuals
- Incarcerated populations
- Drug users
Diagnostic Investigations
-
Essential
Nucleic Acid Amplification Test (NAAT)First-line diagnostic test. Available at all Australian pathology laboratories. Superior sensitivity and specificity compared to microscopy or culture. Can be performed on urine, vaginal swab, or cervical swab.
-
Available
Wet Mount MicroscopyPoint-of-care test if available. Look for motile trichomonads. Sensitivity only 60-70% in women, 40-60% in men. Must be examined within 10 minutes of collection.
-
Available
CultureTraditional gold standard but slower turnaround (2-7 days). Less sensitive than NAAT but useful for antimicrobial resistance testing if treatment failure occurs.
-
Essential
Comprehensive STI ScreenTest for chlamydia, gonorrhoea, syphilis, HIV, and hepatitis B as co-infections are common. Consider herpes simplex testing if ulcerative lesions present.
-
Available
Vaginal pH TestingpH >4.5 supportive of trichomoniasis but non-specific. Can help differentiate from candidiasis (pH typically <4.5).
Specimen Collection
1
Women
Self-collected vaginal swab (preferred) or clinician-collected vaginal/cervical swab. First-catch urine acceptable but less sensitive than vaginal specimens.
2
Men
First-catch urine (preferred) or urethral swab. Collect at least 2 hours after last urination. Urethral swabs more sensitive but less acceptable to patients.
3
Transport
Transport specimens at room temperature within 24 hours. For remote areas, NAAT specimens stable for 48-72 hours at room temperature.
Differential Diagnosis
Bacterial Vaginosis
Fishy odour, thin grey discharge, clue cells on microscopy
Vulvovaginal Candidiasis
Thick white discharge, intense pruritus, pH <4.5
Chlamydia/Gonorrhoea
Often asymptomatic, may present with similar urogenital symptoms
Non-specific Urethritis
Male urethral symptoms without identifiable pathogen
Critical: Always test sexual partners and consider expedited partner therapy. Untreated partners are the primary cause of reinfection.
Testing in Special Populations
Pregnancy
NAAT Testing
Safe and preferred. Associated with preterm birth, low birth weight, and PROM if untreated.
Screening
Consider routine screening in high-risk pregnancies, especially ATSI women.
ATSI Communities
Enhanced Screening
Higher prevalence rates. Consider annual screening for sexually active individuals.
Point-of-Care
Utilise rapid NAAT where available to improve treatment completion rates.
Adolescents
Confidential Testing
Can consent to STI testing from age 14+ in most states. Ensure privacy and confidentiality.
Self-Collection
Vaginal self-swabs preferred to reduce examination anxiety and improve acceptability.
Treatment of Trichomoniasis
First-Line Antimicrobial Therapy
Recommended: Metronidazole is the first-line treatment for trichomoniasis with excellent efficacy and PBS availability.
Metronidazole
Flagyl® · Metrogyl® · First-line therapy
Adult Dose
2g single dose OR 400mg BD for 7 days
Paediatric
15mg/kg/dose BD (max 400mg BD) for 7 days
Route
Oral
Frequency
Single dose or twice daily
Duration
Single dose or 7 days
Renal Adj.
No adjustment required
Hepatic Adj.
Reduce dose 50% in severe impairment
PBS Status
✓ PBS General Benefit
Alcohol Interaction: Advise patients to avoid alcohol during treatment and for 48 hours after completion due to disulfiram-like reaction.
Alternative Antimicrobial Therapy
Tinidazole
Fasigyn® · Alternative nitroimidazole
Adult Dose
2g single dose OR 500mg BD for 5 days
Paediatric
50mg/kg single dose (max 2g) for children >12 years
Route
Oral
Frequency
Single dose or twice daily
Duration
Single dose or 5 days
Renal Adj.
No adjustment required
Hepatic Adj.
Reduce dose in severe impairment
PBS Status
⚡ PBS Restricted Benefit
Treatment Considerations
1
Partner Treatment
Treat all sexual partners simultaneously to prevent reinfection. Contact tracing for partners within 60 days of diagnosis.
2
Sexual Abstinence
Abstain from sexual activity until both patient and partner(s) complete treatment and are asymptomatic for 1 week.
3
Co-infection Screening
Test for other STIs including chlamydia, gonorrhoea, syphilis, HIV, and hepatitis B as appropriate.
Treatment Failure and Resistance
Treatment Failure: Consider resistance if symptoms persist after appropriate treatment. Exclude reinfection first.
High-Dose Metronidazole
For treatment failure
Adult Dose
400mg TDS for 7 days OR 2g daily for 3-5 days
Duration
7 days (first attempt) or 3-5 days (second attempt)
Monitoring
Monitor for peripheral neuropathy with prolonged use
PBS Status
✓ PBS General Benefit
Special Populations
Pregnancy
Metronidazole
Safe in all trimesters. Use 400mg BD for 7 days (avoid single high dose)
Tinidazole
Avoid in first trimester; safe in second and third trimesters
Paediatrics
Metronidazole
15mg/kg BD for 7 days (max 400mg BD). Safe from birth
Consideration
Investigate for sexual abuse in prepubertal children
Elderly
Dosing
Standard adult doses appropriate. Monitor for side effects
Interactions
Check for warfarin interactions - may need INR monitoring
Renal Impairment
Metronidazole
No dose adjustment required for mild-moderate impairment
Dialysis
Removed by dialysis - give after dialysis session
Hepatic Impairment
Metronidazole
Reduce dose by 50% in severe hepatic impairment
Monitoring
Monitor for accumulation and adverse effects
Immunocompromised
Treatment
Standard regimens effective. May need longer courses
Follow-up
More frequent follow-up and test of cure recommended
Monitoring Parameters
Baseline
Clinical Assessment: Symptom severity, partner status, co-infections
Baseline Tests: STI screen, consider pregnancy test
Baseline Tests: STI screen, consider pregnancy test
During Treatment
Adherence: Counsel on completion of full course
Alcohol Avoidance: Emphasise no alcohol during and 48 hours after treatment
Alcohol Avoidance: Emphasise no alcohol during and 48 hours after treatment
1 Week Post-Treatment
Clinical Review: Symptom resolution, partner treatment confirmation
Sexual Activity: Safe to resume if asymptomatic and partner treated
Sexual Activity: Safe to resume if asymptomatic and partner treated
4-6 Weeks
Test of Cure: Only if symptoms persist or high-risk patients
Repeat STI Screening: 3 months for high-risk patients
Repeat STI Screening: 3 months for high-risk patients
PBS Status Summary
| Medication | PBS Status | Authority Required | Cost to Patient |
|---|---|---|---|
| Metronidazole 400mg tablets |