Infectious Disease · Sexually Transmitted Infections
The facts most likely to be tested
Trichomoniasis is caused by the flagellated protozoan *Trichomonas vaginalis*.
The classic physical exam finding is a strawberry cervix due to punctate cervical hemorrhages.
Patients typically present with profuse, frothy, yellow-green vaginal discharge and vulvar pruritus.
Microscopic examination of a wet mount reveals motile, pear-shaped trichomonads.
The vaginal pH in trichomoniasis is consistently elevated (> 4.5).
The first-line treatment for both the patient and their sexual partners is oral metronidazole.
Patients must be advised to abstain from alcohol during treatment and for 48 hours after completion to avoid a disulfiram-like reaction.
Vignette unlocked
A 24-year-old female presents to the clinic complaining of a persistent, foul-smelling vaginal discharge for the past week. She reports associated vulvar pruritus and dysuria. On pelvic examination, the vaginal mucosa is erythematous, and the cervix displays punctate hemorrhages described as a strawberry cervix. A wet mount of the discharge shows motile, flagellated organisms and a pH of 5.2.
What is the most appropriate treatment for this patient and her sexual partner?
Oral metronidazole
The vignette describes the classic presentation of trichomoniasis, which is confirmed by the presence of motile protozoa on wet mount; the standard of care is oral metronidazole for the patient and all sexual partners.
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Etiology / Epidemiology
Caused by Trichomonas vaginalis, a flagellated protozoan. Most common non-viral STI globally.
Clinical Manifestations
Presents with frothy yellow-green discharge and strawberry cervix. Often asymptomatic in men.
Diagnosis
Nucleic acid amplification testing (NAAT) is the gold standard. Wet mount shows motile trichomonads.
Treatment
Metronidazole 2g orally as a single dose. Avoid alcohol during treatment.
Prognosis
Associated with preterm birth and increased HIV transmission risk.
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Epidemiology & Etiology
Infection is caused by the anaerobic protozoan Trichomonas vaginalis. It is the most prevalent non-viral STI, disproportionately affecting sexually active women. Transmission occurs via direct genital-to-genital contact.
Pertinent Anatomy
The organism primarily colonizes the urogenital tract, specifically the vagina, urethra, and Skene's glands. In males, it often resides in the prostate and seminal vesicles, serving as a reservoir for reinfection.
Pathophysiology
The parasite disrupts the normal vaginal flora by increasing the vaginal pH > 4.5. It causes micro-hemorrhages in the cervical epithelium, leading to the classic inflammatory response. This inflammation facilitates the breakdown of mucosal barriers, significantly increasing susceptibility to HIV acquisition.
Clinical Manifestations
Patients typically report malodorous, frothy yellow-green discharge and vulvar pruritus. The pathognomonic finding is the strawberry cervix (colpitis macularis) seen on speculum exam. Dysuria and dyspareunia are common, though many patients remain asymptomatic.
Diagnosis
The NAAT is the most sensitive and specific diagnostic modality. A wet mount microscopy showing motile trichomonads is highly specific but lacks sensitivity. A pH > 4.5 and a positive whiff test are supportive clinical findings.
Treatment
Metronidazole 2g orally in a single dose is the first-line therapy for both patients and their partners. Avoid alcohol for 24 hours post-dose due to the disulfiram-like reaction. If treatment fails, consider tinidazole or extended-course metronidazole.
Prognosis
Untreated infection is linked to preterm delivery, low birth weight, and pelvic inflammatory disease. Patients should be screened for other STIs, and partner notification is mandatory to prevent reinfection.
Differential Diagnosis
Bacterial Vaginosis: Clue cells and fishy odor
Candidiasis: Thick white curdy discharge and pH < 4.5
Gonorrhea: Purulent endocervical discharge
Chlamydia: Often asymptomatic or post-coital bleeding
Atrophic Vaginitis: Occurs in post-menopausal women with low estrogen