What is the diagnostic workup and treatment for a female patient of reproductive age presenting with symptoms of both bacterial vaginosis and candidiasis?

Diagnosis and Treatment of Concurrent Bacterial Vaginosis and Candidiasis

When both bacterial vaginosis and vulvovaginal candidiasis are present simultaneously, treat both conditions concurrently with oral metronidazole 500 mg twice daily for 7 days for BV plus either a single dose of oral fluconazole 150 mg or topical azole therapy for 7 days for candidiasis. 1, 2, 3

Diagnostic Workup

Initial Specimen Collection

• Collect vaginal discharge from the vaginal walls (not the cervix) using a swab, as this provides superior diagnostic performance for both conditions 4
• Prepare two slides: one with 1-2 drops of 0.9% normal saline and another with 10% potassium hydroxide (KOH) 1
• Measure vaginal pH BEFORE applying KOH or performing wet mount, as subsequent testing may alter results 4

Diagnostic Criteria for Bacterial Vaginosis

Use either Amsel clinical criteria (requiring 3 of 4 findings) or Gram stain with Nugent scoring, with Gram stain being the gold standard when available 4, 3

The four Amsel criteria are: 1

• Homogeneous white noninflammatory discharge adhering to vaginal walls
• Vaginal pH >4.5
• Positive whiff test (fishy odor with 10% KOH application)
• Clue cells present on microscopic examination (≥20% of epithelial cells)

Diagnostic Criteria for Vulvovaginal Candidiasis

• Identify yeast or pseudohyphae on KOH wet mount microscopy 1
• Clinical signs include vulvovaginal itching, burning, white discharge, erythema, painful intercourse, and stinging on urination 5
• Culture is more sensitive than microscopy but should be reserved for complicated cases or when identifying non-albicans Candida species 6

Critical Diagnostic Pitfalls to Avoid

• Never culture for Gardnerella vaginalis—it is present in 50% of normal women and is not specific for BV diagnosis 1, 4
• The absence of yeast on microscopy does not exclude candidiasis, as microscopy has limited sensitivity 1
• Up to 50% of women with BV are completely asymptomatic, so absence of symptoms does not exclude the diagnosis 1, 7

Treatment Protocol for Concurrent Infections

Bacterial Vaginosis Treatment

First-line therapy: 1, 3

• Metronidazole 500 mg orally twice daily for 7 days
• Patients must avoid alcohol during treatment and for 24 hours after completion 1

Alternative regimens: 1, 3

• Metronidazole 2 g orally as a single dose (though 7-day regimen is preferred)
• Intravaginal metronidazole gel
• Oral or intravaginal clindamycin cream

Vulvovaginal Candidiasis Treatment

For uncomplicated candidiasis (75% of cases): 2, 3, 6

• Fluconazole 150 mg orally as a single dose achieves 55% therapeutic cure rate (clinical resolution plus negative culture) 2
• Topical azole therapy for 7 days is equally effective 3

For complicated or symptomatic candidiasis requiring longer therapy: 3

• Topical azoles for 7-14 days
• Oral fluconazole may require extended dosing

Concurrent Treatment Strategy

• Administer both treatments simultaneously—there is no contraindication to concurrent therapy 3, 6
• The metronidazole 7-day course for BV can be given alongside either single-dose fluconazole or a 7-day topical azole for candidiasis 2, 3
• Mixed infections between BV and candidiasis occur in approximately 26.6% of cases, making concurrent treatment a common clinical scenario 8

Special Considerations

Pregnancy

• In pregnancy, use only topical azoles for candidiasis (oral fluconazole is not recommended) 6
• Metronidazole can be used for symptomatic BV in pregnancy 3

Recurrent Infections

For recurrent vulvovaginal candidiasis (≥4 episodes per year): 3

• Following initial therapy, maintenance with weekly oral fluconazole for up to 6 months enhances treatment success
• Longer courses of topical azoles (7-14 days) may be required

For recurrent bacterial vaginosis: 3, 9

• Longer courses of therapy are recommended for documented multiple recurrences
• Consider vaginal boric acid as an alternative if first-line extended therapy fails 9

Treatment Failure

• If symptoms persist after treatment, reconsider the diagnosis 9
• Evaluate for alternative causes including desquamative inflammatory vaginitis, genitourinary syndrome of menopause, or vulvodynia 9
• For candidiasis treatment failure, culture to identify non-albicans Candida species that may require alternative antifungal therapy 6

Partner Management

• Male partner treatment is NOT beneficial for preventing BV recurrence and is not recommended 1
• Partner treatment is not routinely indicated for candidiasis unless the partner is symptomatic 3