What is the difference in diagnosis and treatment between bacterial vaginosis (BV) and a yeast infection?

Diagnosis and Treatment Differences Between Bacterial Vaginosis (BV) and Yeast Infections

Bacterial vaginosis and yeast infections (vulvovaginal candidiasis) have distinct diagnostic features and treatment approaches, with BV requiring antibiotics like metronidazole 500mg twice daily for 7 days, while yeast infections are treated with topical azoles or fluconazole 150mg as a single dose. 1

Diagnostic Differences

Clinical Presentation

Feature	Bacterial Vaginosis	Vulvovaginal Candidiasis
Discharge	Homogeneous, white, thin	White, thick, "cottage cheese-like"
Odor	Fishy or musty (especially after sex or with KOH)	Usually minimal or none
pH	>4.5	≤4.5 (normal)
Key symptom	Discharge and odor	Intense itching
Microscopy	Clue cells (epithelial cells with adherent bacteria)	Yeast cells and pseudohyphae

Diagnostic Methods

1. Vaginal pH Testing:

   • BV: pH >4.5
   • Yeast: pH ≤4.5 (normal)

2. Microscopic Examination:

   • BV: Clue cells on saline wet mount, reduced lactobacilli, predominance of small bacteria
   • Yeast: Pseudohyphae and budding yeast cells (better visualized with 10% KOH preparation)

3. Whiff Test (Amine Test):

   • BV: Positive (fishy odor when 10% KOH added to discharge)
   • Yeast: Negative

4. Nugent Score (for BV):

   • Score ≥4 indicates BV (based on Gram stain evaluation of bacterial morphotypes)
   • Score 0-3 considered normal

Treatment Approaches

Bacterial Vaginosis Treatment

1. First-line Treatment:

   • Metronidazole 500mg orally twice daily for 7 days (95% cure rate) 1

2. Alternative Treatments:

   • Metronidazole gel 0.75%, one full applicator intravaginally once daily for 5 days
   • Clindamycin cream 2%, one full applicator intravaginally at bedtime for 7 days
   • Tinidazole 2g orally once daily for 2 days or 1g once daily for 5 days (shown superior to placebo) 2
   • Clindamycin 300mg orally twice daily for 7 days
   • Clindamycin ovules 100g intravaginally once at bedtime for 3 days

3. Special Considerations:

   • Avoid alcohol during metronidazole treatment and for 24 hours after
   • Clindamycin cream and ovules may weaken latex condoms and diaphragms
   • No routine treatment of sexual partners recommended
   • Recurrence is common

Yeast Infection Treatment

1. First-line Treatment:

   • Topical azoles (various formulations available over-the-counter)
   • Fluconazole 150mg oral single dose

2. For Recurrent Infections:

   • Extended duration of first-line agents
   • Boric acid vaginal suppositories as an alternative option 3

Important Clinical Pearls

• Self-diagnosis pitfalls: Many women incorrectly self-diagnose and treat with over-the-counter antifungals when they actually have BV, leading to delayed proper treatment 1

• Mixed infections: It's not uncommon for a woman to have both conditions simultaneously, requiring comprehensive testing and potentially dual treatment 4

• Recurrence management:

  • BV: Consider extended antibiotic courses or alternative regimens
  • Yeast: Extended antifungal regimens may be needed

• Pregnancy considerations: Treatment options differ in pregnancy, with clindamycin cream preferred in first trimester for BV, and metronidazole or clindamycin in later trimesters 1

• Alcohol warning: Patients on metronidazole must avoid alcohol during treatment and for 24 hours afterward to prevent disulfiram-like reactions 1

Follow-up Recommendations

• Follow-up visits generally not necessary if symptoms resolve 1
• Patients should return if symptoms recur
• Pregnant women should have follow-up evaluation one month after completing treatment 1