Group B Streptococcus Treatment Guidelines

First-Line Treatment

The Centers for Disease Control and Prevention recommends Penicillin G as the preferred agent for Group B Streptococcus treatment due to its narrow spectrum of activity, universal susceptibility, and proven efficacy 1, 2
All Group B Streptococcus isolates worldwide remain universally susceptible to penicillin, with no documented resistance 3
Ampicillin is an acceptable alternative to Penicillin G, but has a broader spectrum of activity 1, 2

For patients with non-severe penicillin allergy, the American College of Obstetricians and Gynecologists recommends Cefazolin as the preferred alternative 2, 3, 4
Cross-reactivity between penicillins and cephalosporins occurs in approximately 10% of patients with penicillin allergy 3, 4
For patients with severe penicillin allergy, the Centers for Disease Control and Prevention recommends obtaining susceptibility testing for clindamycin and erythromycin on the Group B Streptococcus isolate 2, 3, 4

The Infectious Diseases Society of America recommends susceptibility testing when using clindamycin or erythromycin for penicillin-allergic patients 2, 3
The American College of Obstetricians and Gynecologists advises against using oral antibiotics to treat Group B Streptococcus colonization outside of active labor or infection, as this is ineffective in eliminating carriage and may promote resistance 1, 5, 6
The Centers for Disease Control and Prevention recommends reserving vancomycin for cases where no other options exist to minimize promoting antimicrobial resistance 4

The American College of Obstetricians and Gynecologists recommends that pregnant women with Group B Streptococcus bacteriuria at any concentration during pregnancy require both treatment of the urinary tract infection and intrapartum prophylaxis during labor 6
Women with Group B Streptococcus colonization detected at 35-37 weeks require intrapartum prophylaxis during labor, not antepartum treatment 1, 2, 6
The Centers for Disease Control and Prevention recommends combination therapy with ampicillin plus gentamicin for neonates with suspected sepsis to provide synergistic killing and broader coverage 2

The Centers for Disease Control and Prevention (CDC) recommends intrapartum antibiotic prophylaxis for women with a documented history of GBS bacteriuria during pregnancy, regardless of current culture results or clinical status 7, 8
GBS bacteriuria at any concentration during pregnancy is a strong indication for intrapartum prophylaxis, as it indicates heavy colonization and significantly increases the risk of early-onset neonatal GBS disease 7, 8

The CDC guidelines recommend penicillin G 5 million units IV initial dose, then 2.5-3.0 million units IV every 4 hours until delivery for intrapartum prophylaxis 7, 8, 9, 10
Penicillin G is preferred over ampicillin due to its narrower spectrum of activity, which reduces selection pressure for resistant organisms 7
Optimal prophylaxis requires at least 4 hours of administration before delivery to achieve adequate fetal tissue levels 9, 10

A documented GBS bacteriuria episode during prenatal care mandates intrapartum prophylaxis regardless of prior treatment, current maternal temperature, current urinalysis findings, or presence or absence of symptoms 7, 11, 9
The CDC guidelines explicitly state that women with GBS bacteriuria detected during the current pregnancy should receive intrapartum prophylaxis regardless of other factors 7, 8

For patients with a penicillin allergy without high-risk features, cefazolin 2g IV initial dose, then 1g IV every 8 hours until delivery is recommended 7, 8
For patients with a high-risk penicillin allergy and a susceptible isolate, clindamycin 900 mg IV every 8 hours until delivery is recommended, but susceptibility testing is essential due to increasing resistance 7, 8