Management of Group B Streptococcus in Urine

Introduction to Treatment

For patients with Group B streptococcus (GBS) in urine who have a penicillin allergy, cefazolin is the recommended first-line alternative for those without a history of anaphylaxis, while clindamycin or vancomycin should be used for those with high-risk penicillin allergies, based on susceptibility testing 1, 2
Determining the severity of penicillin allergy is crucial to guide treatment decisions for patients with Group B streptococcal infections and penicillin allergy, as recommended by the Centers for Disease Control and Prevention (CDC) 2

The CDC recommends cefazolin as the first-line choice due to its narrow spectrum of activity and ability to achieve high concentrations, with cross-reactivity between penicillins and cephalosporins occurring in approximately 10% of patients 1, 2
Clindamycin should only be used if the GBS isolate is confirmed susceptible, with susceptibility testing being mandatory due to increasing resistance 1, 2
Vancomycin should be reserved for cases where clindamycin resistance is documented or susceptibility is unknown, and should be used when other options are not available due to concerns about vancomycin resistance 1, 2
Erythromycin is no longer recommended due to high resistance rates, as stated by the CDC 2
Cefazolin 1-2g IV every 8 hours or appropriate oral cephalosporin is recommended as first-line treatment for patients with low-risk penicillin allergy, as recommended by the CDC and the Infectious Diseases Society of America (IDSA) 2, 3
Clindamycin 900mg IV every 8 hours or 300-450mg orally 3-4 times daily can be used if the isolate is susceptible, as recommended by the CDC 2, 1
Vancomycin 1g IV every 12 hours is an alternative if susceptibility unknown or resistant to clindamycin, as recommended by the CDC 1, 2

The CDC recommends susceptibility testing for all GBS isolates from patients with high-risk penicillin allergy, with the D-zone test required to detect inducible clindamycin resistance if the isolate is erythromycin-resistant but clindamycin-susceptible 1, 2
Approximately 20% of GBS isolates are resistant to clindamycin, and 31% of streptococcal isolates may be resistant to azithromycin, highlighting the importance of susceptibility testing 2

The CDC advises that susceptibility testing should be performed before initiating treatment, and treatment duration should be 7-14 days depending on clinical response and severity 2
Follow-up culture should be obtained after treatment completion to confirm eradication 2

Pregnant women with Group B streptococcal bacteriuria should follow CDC guidelines for intrapartum prophylaxis, regardless of whether they received treatment earlier in pregnancy 2
Patients with ruptured membranes undergoing C-section should receive antibiotic prophylaxis as soon as possible, ideally at least 30-60 minutes before incision, as recommended by the American College of Obstetricians and Gynecologists (ACOG) and the CDC 2
Neonates born to mothers with inadequate GBS prophylaxis may require additional monitoring or empiric treatment, including limited evaluation with blood culture and CBC with differential, as recommended by the CDC 2

Antibiotic	Dosage	Redosing Interval
Cefazolin	2g IV initial dose, then 1g IV every 8 hours	4 hours
Clindamycin	900mg IV every 8 hours	6 hours
Vancomycin	1g IV every 12 hours	8-12 hours

Consider adding gentamicin for gram-negative coverage in addition to GBS-active agents, as recommended by the IDSA 4
Patients with a history of asthma or other conditions that would make anaphylaxis more dangerous should avoid both penicillins and cephalosporins due to high-risk for anaphylaxis, as recommended by the CDC 1
Failing to verify penicillin allergy history can lead to unnecessary use of alternative antibiotics, as many reported penicillin allergies are not true allergies or do not pose risk for anaphylaxis 1
Using erythromycin without susceptibility testing is not recommended due to high resistance rates, and using clindamycin without confirming susceptibility can lead to treatment failure 1, 2
Not performing D-zone testing can lead to undetected inducible clindamycin resistance, and overuse of vancomycin can promote resistance 1, 2