STDs: Protozoa

Snapshot

• A 45-year-old woman presents to an urgent care clinic for green foul-smelling vaginal discharge for the past few days. She reports that she has had unprotected sex with one new sexual partner, but she wasn’t worried about sexually transmitted diseases. She has not had any fevers or chills but has had dysuria and dyspareunia. She also noticed postcoital bleeding yesterday. Pelvic exam shows green foul-smelling vaginal discharge and an erythematous vulva. The vaginal pH is 5.5 and a wet mount shows motile trichomonads. She is started on metronidazole.

Introduction

• Sexually transmitted diseases caused by protozoa include
  • Trichomonas vaginalis
• Classification
  • T. vaginalis
    • protozoa
    • causes vulvovaginitis in women
    • causes urethritis in men
    • a sexually transmitted disease
• Epidemiology
  • demographics
    • women > men
  • risk factors
    • new sexual partners
    • multiple sexual partners
    • injection drug use
    • unprotected sex
• Pathogenesis
  • protozoa thrives in the vagina or urethra
  • it attaches to the walls of the vagina, causing inflammation
• Associated conditions
  • HIV infection
  • herpes simplex virus type 2
• Prognosis
  • asymptomatic in men
• may recur

Presentation

• Symptoms
  • dyspareunia
  • dysuria
  • vulvar itching and burning
  • postcoital bleeding
• Physical exam
  • malodorous green discharge
  • “strawberry” cervix
• vulvovaginal erythema

Studies

• Labs
  • vaginal pH 5-6
  • wet mount microscopy 
    • motile trichomonads 
  • positive culture from urethral swab, urine, or semen in men
    • also used to confirm diagnosis in women if wet mount is equivocal
• Making the diagnosis
• most cases are clinically diagnosed and confirmed on wet mount microscopy

Differential

• Vulvovaginal candidiasis 
  • distinguishing factors
    • thick white curd-like vaginal discharge
    • often very itchy with vulvar erythema and edema
• Bacterial vaginosis 
  • distinguishing factors
    • thin white-gray discharge
    • fishy odor
    • clue cells on wet mount microscopy
• normal vulva

Treatment

• Management approach 
  • sexual partners should be treated as this is a sexually transmitted disease
• Conservative
  • abstinence
    • indication
      • for all patients until treatment is complete
• Medical
  • metronidazole
    • indication
      • all patients
  • tinidazole
    • indication
• patients with contraindication to metronidazole

Complications

• Premature rupture of membranes
• Prematurity of fetus