What is the recommended treatment for a patient with asymptomatic Group B Streptococcus (GBS) bacteriuria, with a colony count of 50,000, and normal urinalysis results?

Management of Asymptomatic Group B Streptococcus Bacteriuria in Pregnancy

For a patient with asymptomatic Group B Streptococcus (GBS) bacteriuria with a colony count of 50,000 CFU/ml and normal urinalysis, intrapartum antibiotic prophylaxis (IAP) during labor is recommended, but current treatment of the bacteriuria is not necessary. 1

Significance of GBS Bacteriuria in Pregnancy

GBS bacteriuria during pregnancy is a marker for heavy genital tract colonization and is associated with an increased risk of early-onset GBS disease in newborns. Key points include:

• GBS bacteriuria at any concentration during pregnancy is considered significant, affecting 2-7% of pregnant women 1
• Even low colony counts (<10^4 CFU/ml) are associated with increased risk for early-onset neonatal disease 1
• Colony counts of 50,000 (5×10^4) CFU/ml, as in this case, are considered clinically significant 2

Current Management Recommendations

Immediate Management

• For asymptomatic GBS bacteriuria with normal urinalysis, there is no need for immediate antibiotic treatment 2, 3
• The 2019 IDSA guidelines for asymptomatic bacteriuria do not recommend treatment for asymptomatic bacteriuria in most non-pregnant populations 2

Intrapartum Management

• Women with GBS bacteriuria during any trimester of the current pregnancy should receive intrapartum antibiotic prophylaxis (IAP) during labor, regardless of subsequent negative cultures 1
• This recommendation is based on CDC guidelines and is intended to prevent early-onset GBS disease in the newborn 2, 1

Recommended IAP Regimens

For labor and delivery, the following regimens are recommended:

• First-line: Penicillin G (5 million units IV initial dose, then 2.5-3.0 million units IV every 4 hours until delivery)
• Alternative: Ampicillin (2 g IV initial dose, then 1 g IV every 4 hours until delivery)
• For penicillin-allergic patients: Cefazolin (2 g IV initial dose, then 1 g IV every 8 hours) if no history of anaphylaxis 1

Important Clinical Considerations

Documentation

• Document the presence of GBS bacteriuria in the patient's prenatal record to ensure appropriate management during labor 2
• No repeat urine culture is necessary if asymptomatic, as the patient will require IAP regardless of subsequent culture results 1

Misconceptions to Avoid

• Do not treat asymptomatic GBS bacteriuria with oral antibiotics before labor, as this approach does not eliminate colonization and may promote antimicrobial resistance 1
• Recolonization after treatment is common, and treating before the intrapartum period is not effective in preventing early-onset GBS disease 1
• A normal urinalysis does not rule out significant bacteriuria; the presence of GBS in urine is what determines the need for IAP 4

Special Situations

• If the patient has a history of severe penicillin allergy, antimicrobial susceptibility testing should be ordered for the GBS isolate to guide alternative antibiotic selection 1
• Clindamycin can be used if susceptibility testing confirms sensitivity, but GBS has 14-26.6% resistance rates to clindamycin 1

Follow-up

• No additional screening or treatment is needed during the current pregnancy 2
• The patient should be counseled about the need for IAP during labor to prevent neonatal GBS disease 1
• Ensure that information about GBS bacteriuria is communicated to all providers involved in the patient's care, particularly those who will manage labor and delivery 2