What are the treatment options for a pregnant woman or newborn at risk of Group B strep (Streptococcus agalactiae) and thrush (candidiasis)?

Group B Strep and Thrush Management

Treat thrush immediately with topical antifungal therapy, but do NOT treat GBS vaginal colonization outside of labor—reserve GBS treatment exclusively for intrapartum IV antibiotic prophylaxis during active labor. 1

Critical Management Principle: GBS Colonization vs. GBS Infection

The CDC explicitly states that antimicrobial agents should NOT be used before the intrapartum period to treat asymptomatic GBS colonization, as prenatal treatment is completely ineffective at eliminating carriage, does not prevent neonatal disease, and promotes antibiotic resistance. 2, 1 This is a Grade D-I recommendation (evidence supports NOT doing this intervention). 1

Exception: GBS bacteriuria (any concentration in urine) during pregnancy requires immediate treatment of the UTI AND mandatory intrapartum prophylaxis during labor, regardless of whether the UTI was treated earlier. 3, 1

Treatment Algorithm

Step 1: Treat Thrush Immediately

For non-pregnant patients:

• Topical azole therapy (clotrimazole, miconazole) for 7 days, OR
• Oral fluconazole 150 mg single dose 1

For pregnant patients:

• Topical azole therapy ONLY (clotrimazole, miconazole) for 7 days 1
• Avoid oral fluconazole in pregnancy: FDA labeling reports epidemiological studies suggest potential risk of spontaneous abortion and congenital abnormalities with 150 mg fluconazole in the first trimester, though findings have limitations. 4 Animal studies show embryolethality and fetal abnormalities at higher doses. 4

Step 2: GBS Screening and Intrapartum Prophylaxis (Pregnant Patients Only)

Screening timing: Perform vaginal-rectal culture at 36 0/7 to 37 6/7 weeks gestation (updated from previous 35-37 weeks recommendation). 5

Specimen collection technique: Swab the lower vagina first, then insert the same swab through the anal sphincter into the rectum to maximize GBS detection. 2, 3

Step 3: Intrapartum Antibiotic Prophylaxis During Labor

Indications for intrapartum prophylaxis: 2, 5

• Positive GBS vaginal-rectal culture at 36-37 weeks
• GBS bacteriuria at any concentration during current pregnancy
• Previous infant with GBS disease
• Unknown GBS status with risk factors: delivery <37 weeks, membrane rupture >18 hours, or intrapartum temperature >100.4°F (>38.0°C)

First-line regimen (no penicillin allergy): 2, 3, 5

• Penicillin G: 5 million units IV initially, then 2.5 million units IV every 4 hours until delivery (preferred due to narrow spectrum)
• Ampicillin: 2 g IV initially, then 1 g IV every 4 hours until delivery (acceptable alternative)

For penicillin allergy (not high-risk for anaphylaxis): 2, 3

• Cefazolin: 2 g IV initially, then 1 g IV every 8 hours until delivery

For penicillin allergy (high-risk for anaphylaxis—history of anaphylaxis, angioedema, urticaria, or asthma): 2, 3

• Clindamycin: 900 mg IV every 8 hours until delivery (ONLY if isolate confirmed susceptible; ~20% of GBS isolates are resistant) 3, 6
• Vancomycin: 1 g IV every 12 hours until delivery (if clindamycin resistance or susceptibility unknown) 2, 3

Timing matters: Intrapartum prophylaxis administered ≥4 hours before delivery is 78% effective in preventing early-onset neonatal GBS disease. 3, 5 However, even 2 hours of antibiotic exposure reduces GBS vaginal colony counts and decreases clinical neonatal sepsis. 5

Special Circumstances

Planned Cesarean Delivery Before Labor

Women undergoing planned cesarean delivery before labor onset and membrane rupture do NOT require intrapartum GBS prophylaxis. 2, 1

Preterm Labor or Preterm Premature Rupture of Membranes (PPROM)

• Start GBS prophylaxis immediately upon admission with signs of preterm labor or PPROM at <37 weeks. 2
• If true labor does not develop, discontinue GBS prophylaxis. 2
• For PPROM, ampicillin 2 g IV once, followed by 1 g IV every 6 hours for at least 48 hours serves dual purpose for latency and GBS prophylaxis. 2

GBS Bacteriuria During Pregnancy

• Treat the acute UTI immediately with standard pregnancy-safe antibiotics (e.g., amoxicillin 500 mg every 8 hours for 7-10 days). 3
• Critical: Still provide intrapartum IV prophylaxis during labor even if UTI was treated earlier, as treatment does NOT eliminate GBS colonization from the genitourinary tract. 3, 1

Common Pitfalls to Avoid

Do NOT attempt to "decolonize" GBS with oral or IV antibiotics during pregnancy outside of labor. This is ineffective, promotes antibiotic resistance, and may cause adverse drug effects without clinical benefit. 2, 3, 1

Do NOT confuse GBS vaginal colonization with GBS urinary tract infection. Only GBS bacteriuria requires prenatal treatment; vaginal colonization is managed exclusively with intrapartum prophylaxis. 3, 1

Do NOT delay necessary obstetric interventions solely to provide 4 hours of antibiotic administration before birth. While 4+ hours is optimal, 2 hours still provides benefit. 5

Do NOT use oral fluconazole for thrush in pregnant patients. Use topical azole therapy only. 1, 4

Do NOT assume negative GBS screening remains valid indefinitely. A negative GBS screen is valid for only 5 weeks; rescreen if patient presents with preterm labor >5 weeks after initial negative screen. 2