What is the treatment for bacterial vaginosis (BV) vs urinary tract infection (UTI)?

Bacterial Vaginosis vs UTI: Treatment Approach

Bacterial vaginosis requires metronidazole 500 mg orally twice daily for 7 days, while uncomplicated UTIs are treated with nitrofurantoin, fosfomycin, or trimethoprim-sulfamethoxazole as first-line agents.

Distinguishing Between BV and UTI

Bacterial Vaginosis Presentation

• Vaginal discharge and malodor are the hallmark symptoms, with a homogeneous white discharge that adheres to vaginal walls 1
• Vaginal pH >4.5 and positive whiff test (fishy odor with KOH) are diagnostic features 1
• Clue cells on microscopy confirm the diagnosis when combined with other Amsel criteria (need 3 of 4 criteria) 1, 2
• Notably, 50% of women with BV are asymptomatic despite meeting diagnostic criteria 1, 3
• Vaginal discharge is present without significant vulvar irritation, distinguishing it from other causes of vaginitis 3

UTI Presentation

• Dysuria, urgency, and increased urinary frequency are the most diagnostic symptoms 4
• Absence of vaginal discharge helps distinguish UTI from BV 4
• Nitrites on dipstick are highly specific for UTI, particularly in elderly patients 4
• Bacteriuria is more specific than pyuria for detecting true infection 4

Treatment of Bacterial Vaginosis

First-Line Therapy

• Metronidazole 500 mg orally twice daily for 7 days achieves 95% cure rate and is the recommended regimen 1, 2
• Patients must avoid alcohol during treatment and for 24 hours after due to disulfiram-like reaction risk 1, 2

Alternative Regimens

• Metronidazole 2g single dose provides 84% cure rate when compliance is a concern 1, 2
• Metronidazole gel 0.75% intravaginally twice daily for 5 days offers lower systemic side effects (<2% of oral bioavailability) 1, 2
• Clindamycin cream 2% intravaginally at bedtime for 7 days is effective but may weaken latex condoms 1, 2
• Clindamycin 300 mg orally twice daily for 7 days is another oral alternative 1

When to Treat BV

• Only symptomatic women require treatment for symptom relief 1, 2
• Asymptomatic women should be treated before surgical abortion as metronidazole substantially reduces post-abortion PID 1, 2
• Consider treatment before hysterectomy or invasive gynecological procedures due to increased postoperative infection risk 2
• High-risk pregnant women with history of preterm delivery may benefit from treatment 2

Treatment of Urinary Tract Infections

First-Line Antibiotics

• Nitrofurantoin remains highly effective as most uropathogens display good sensitivity 4
• Fosfomycin is an appropriate first-line option with minimal collateral damage 4
• Trimethoprim-sulfamethoxazole can be used when local resistance is <20% 4
• These agents minimize resistance development and have limited collateral damage 4

Diagnostic Considerations for UTI

• Urine culture is the gold standard and should be performed when probability is moderate or unclear 4
• Even growth as low as 10² CFU/mL can reflect infection in symptomatic women 4
• Asymptomatic bacteriuria should not be treated except in pregnancy 4
• Positive dipstick in high-probability patients warrants treatment even if culture is pending 4

Critical Pitfalls to Avoid

BV Management Errors

• Do not treat male partners as this does not alter clinical course or reduce recurrence 1, 2
• Recurrence is common (50-80% within a year) and may require retreatment with alternative regimens 3
• Two-thirds of women with typical BV symptoms but negative microscopy respond to metronidazole, suggesting empiric treatment may be reasonable in symptomatic patients 5
• Do not use G. vaginalis culture for diagnosis as it can be isolated from 50% of normal women 1

UTI Management Errors

• Do not treat asymptomatic bacteriuria in non-pregnant women, particularly elderly patients 4
• Pyuria alone does not indicate infection, especially in older adults with incontinence 4
• Negative dipstick does not rule out UTI in patients with high pretest probability based on symptoms 4
• Increasing resistance to fluoroquinolones and beta-lactams makes these less ideal first-line choices 4

Special Populations

Pregnancy

• BV in pregnancy is associated with adverse outcomes including preterm birth 6
• Metronidazole is safe for BV treatment in pregnancy 6
• For UTI in pregnancy, beta-lactams, nitrofurantoin, fosfomycin, and trimethoprim-sulfamethoxazole are appropriate 4
• Urine culture is the test of choice for UTI diagnosis in pregnancy 4