What is the treatment for Group B streptococcus (GBS) vaginitis in pregnant and non-pregnant women?

Group B Streptococcus Vaginitis: Treatment Approach

GBS vaginal colonization is NOT treated outside of labor in pregnant women, and GBS does not cause vaginitis in non-pregnant women—if vaginal symptoms are present, look for other treatable causes like bacterial vaginosis, candidiasis, or trichomoniasis. 1, 2

Critical Distinction: Colonization vs. Infection

GBS colonization of the vagina is fundamentally different from GBS infection and requires completely different management:

In Pregnant Women

• Prenatal antibiotic treatment of GBS vaginal colonization is explicitly contraindicated—it does not prevent neonatal disease, promotes antibiotic resistance, and may cause adverse drug effects 3, 2
• The CDC provides a Grade D-I recommendation (evidence supports NOT doing this intervention) against using antimicrobial agents before the intrapartum period to treat GBS colonization 2
• GBS colonization is only treated during active labor with IV antibiotics to prevent early-onset neonatal disease 3, 2

Screening and Intrapartum Management

• All pregnant women should be screened at 36 0/7 to 37 6/7 weeks gestation with combined vaginal-rectal swabs using the same swab or two separate swabs 3
• Women who test positive receive intrapartum antibiotic prophylaxis during labor: penicillin G 5 million units IV initially, then 2.5-3 million units IV every 4 hours until delivery 3, 4
• This approach reduces early-onset neonatal GBS disease by 78-80% when administered ≥4 hours before delivery 3, 4

In Non-Pregnant Women

• GBS does not cause vaginitis or require treatment in non-pregnant women 1
• If vaginal discharge is present, evaluate for bacterial vaginosis (treat with metronidazole or clindamycin), candidiasis (treat with topical azoles or oral fluconazole), or trichomoniasis (treat with metronidazole) 1, 2

Important Exception: GBS Bacteriuria (UTI)

The only scenario where GBS requires prenatal treatment is GBS bacteriuria at ANY concentration during pregnancy:

• GBS in urine at any concentration (even <10,000 CFU/mL) during pregnancy requires immediate treatment because it indicates heavy genital tract colonization and significantly increases risk of early-onset neonatal disease 1, 4
• Treat the acute UTI with standard pregnancy-safe antibiotics (amoxicillin 500 mg every 8 hours for 7-10 days) 4
• These women STILL require intrapartum IV prophylaxis during labor regardless of whether the UTI was treated earlier in pregnancy, because treating the UTI does not eliminate GBS colonization from the genitourinary tract 4

Common Clinical Pitfalls

• Do not prescribe oral antibiotics for asymptomatic GBS vaginal colonization during pregnancy—this is the most common error and is explicitly contraindicated 3, 2
• Do not confuse GBS colonization with GBS bacteriuria—only bacteriuria (UTI) requires prenatal treatment 2, 4
• Do not assume treating a GBS UTI eliminates the need for intrapartum prophylaxis—recolonization after oral antibiotics is typical, so IV prophylaxis during labor remains mandatory 4

Alternative Regimens for Penicillin Allergy

For women requiring intrapartum prophylaxis who have penicillin allergy:

• Not at high risk for anaphylaxis: cefazolin 2 g IV initially, then 1 g IV every 8 hours until delivery 3, 4
• High risk for anaphylaxis with susceptible isolate: clindamycin 900 mg IV every 8 hours until delivery 3, 4
• High risk for anaphylaxis with resistant or unknown susceptibility: vancomycin 1 g IV every 12 hours until delivery 3, 4