What is the recommended treatment and management for a pregnant female with a suspected Group B strep (GBS) infection confirmed by urinalysis?

Treatment of Group B Streptococcus Detected on Urinalysis in Pregnant Women

All pregnant women with GBS detected in urine at any concentration must receive immediate treatment of the urinary tract infection AND mandatory intravenous antibiotic prophylaxis during labor, regardless of whether the UTI was treated earlier in pregnancy. 1, 2

Critical Understanding: Why Pregnancy Changes Everything

• GBS bacteriuria at any concentration during pregnancy indicates heavy genital tract colonization and significantly increases the risk of early-onset neonatal GBS disease by 29-fold compared to non-colonized mothers. 1, 2

• Treating the acute UTI does NOT eliminate GBS colonization from the genitourinary tract—recolonization after oral antibiotics is typical, which is why intrapartum IV prophylaxis remains mandatory even after UTI treatment. 1

• This management differs fundamentally from non-pregnant patients, where asymptomatic GBS bacteriuria should not be treated. 3, 2

Immediate Treatment of the Acute UTI

First-line oral regimens for symptomatic UTI:

• Penicillin G 500 mg orally every 6-8 hours for 7-10 days 3

• Ampicillin 500 mg orally every 8 hours for 7-10 days 3

For penicillin-allergic patients:

• Clindamycin 300-450 mg orally every 8 hours (requires susceptibility testing due to 3-15% resistance rates) 3, 1

Mandatory Intrapartum Prophylaxis During Labor

All women with GBS bacteriuria at any point during pregnancy automatically qualify for intrapartum prophylaxis—do not re-screen with vaginal-rectal cultures at 35-37 weeks. 1, 2

First-Line Intrapartum Regimens (No Penicillin Allergy)

• Penicillin G: 5 million units IV initially, then 2.5-3.0 million units IV every 4 hours until delivery (preferred agent due to narrow spectrum) 1

• Ampicillin: 2 g IV initially, then 1 g IV every 4 hours until delivery (acceptable alternative with broader spectrum) 1

Alternative Regimens for Penicillin Allergy

For patients NOT at high risk for anaphylaxis:

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

For patients at HIGH risk for anaphylaxis (history of anaphylaxis, angioedema, urticaria, or asthma):

• Clindamycin: 900 mg IV every 8 hours until delivery (ONLY if isolate confirmed susceptible to both clindamycin and erythromycin) 1

• Vancomycin: 1 g IV every 12 hours until delivery (if susceptibility unknown or resistant to clindamycin) 1

• Susceptibility testing for clindamycin and erythromycin must be performed immediately on GBS isolates from high-risk allergic patients, including D-zone testing for inducible resistance. 1

Critical Timing for Maximum Effectiveness

• Intrapartum prophylaxis must be administered at least 4 hours before delivery to achieve maximum effectiveness. 1

• When given ≥4 hours before delivery, prophylaxis reduces early-onset neonatal GBS disease by 78-80%. 1

• Even shorter durations achieve therapeutic levels, but 4 hours is the target for optimal protection. 1

Special Pregnancy Scenarios

Preterm labor (<37 weeks) with GBS bacteriuria:

• Administer GBS prophylaxis immediately at hospital admission. 1

Preterm premature rupture of membranes (PPROM) at ≥24 weeks:

• Ampicillin 2 g IV once, followed by 1 g IV every 6 hours for at least 48 hours provides both latency antibiotics and GBS prophylaxis. 1

GBS-positive patients with PPROM after 34 weeks:

• Not candidates for expectant management due to higher rates of neonatal infectious complications. 4

Laboratory and Communication Requirements

• Laboratories must be informed when urine specimens are from pregnant women so they report GBS at concentrations ≥10,000 CFU/mL (≥10⁴ CFU/mL). 1

• Ensure laboratory reports of GBS bacteriuria are communicated to both the anticipated site of delivery and the ordering provider. 1

• Urine specimen labels from prenatal patients must clearly state pregnancy status to ensure proper laboratory processing. 2

Common Pitfalls to Avoid

• Never assume treating the UTI eliminates the need for intrapartum prophylaxis—this is a dangerous error that leaves the neonate unprotected. 1

• Never prescribe oral or IV antibiotics before labor to "treat" GBS colonization—such treatment is completely ineffective at eliminating carriage and promotes antibiotic resistance. 1

• Failure to provide intrapartum prophylaxis to women with previous GBS bacteriuria increases the risk of early-onset neonatal GBS disease. 1

• Underdosing or premature discontinuation of intrapartum therapy may lead to treatment failure. 1

Neonatal Management Considerations

• Healthy-appearing infants >38 weeks' gestation whose mothers received >4 hours of intrapartum antibiotic prophylaxis may be discharged as early as 24 hours after delivery if other discharge criteria are met and appropriate home observation is available. 1

• Infants of GBS-positive mothers should be under proper observation, and when abnormal symptoms are present, full diagnostic evaluation including blood tests, lumbar puncture, chest X-ray, and cultures should be performed. 5