What is the recommended treatment for group B strep (Streptococcus agalactiae) urinary tract infection (UTI)?

Treatment of Group B Streptococcal Urinary Tract Infections

Penicillin or ampicillin is the first-line treatment for Group B Streptococcus (GBS) urinary tract infections, with all strains showing 100% sensitivity to these antibiotics. 1

First-Line Treatment Options

• Penicillin G is the preferred treatment for GBS infections due to its narrow spectrum of activity and high efficacy 2, 3
• Ampicillin is an acceptable alternative to penicillin for treating GBS UTIs, with studies showing 96% sensitivity of GBS isolates to ampicillin 1, 4
• For outpatient treatment of uncomplicated GBS UTI, oral amoxicillin is an appropriate option based on the documented sensitivity patterns 5
• Complete the full prescribed course of antibiotics to ensure complete eradication and prevent recurrence 3

Treatment for Penicillin-Allergic Patients

• For patients with penicillin allergy who are not at high risk for anaphylaxis, cefazolin or cephalexin is the preferred alternative 2, 3
• For patients at high risk for anaphylaxis, treatment options include:
  • Clindamycin (if the isolate is confirmed susceptible) 2, 3
  • Vancomycin (for severe infections or when susceptibility results are unavailable) 2, 3
• Norfloxacin has shown 96.9% efficacy against GBS isolates and can be considered for patients with penicillin allergy 4
• Nitrofurantoin has demonstrated 95.5% efficacy against GBS urinary isolates and is another alternative for uncomplicated UTIs 4

Importance of Susceptibility Testing

• Susceptibility testing should be performed on GBS isolates from penicillin-allergic patients at high risk for anaphylaxis 3
• Testing for inducible clindamycin resistance is necessary for isolates that are susceptible to clindamycin but resistant to erythromycin 3
• High resistance rates have been observed for tetracycline (81.6%) and co-trimoxazole (68.9%), making these antibiotics poor choices for empiric therapy 4
• Approximately 20% of GBS isolates are resistant to clindamycin, so susceptibility testing should always be performed before using this antibiotic 2

Special Considerations for Pregnant Women

• Women with GBS bacteriuria in any concentration during pregnancy should receive intrapartum antimicrobial prophylaxis during labor to prevent early-onset neonatal GBS disease 6, 7
• No additional screening for GBS is needed in the third trimester for women with documented GBS bacteriuria during the current pregnancy 7
• In the absence of GBS urinary tract infection, antimicrobial agents should not be used before the intrapartum period to treat asymptomatic GBS colonization 6
• Asymptomatic women with urinary GBS colony counts <100,000 CFU/mL in pregnancy should not be treated with antibiotics for prevention of adverse outcomes such as pyelonephritis, chorioamnionitis, or preterm birth 7

Clinical Pitfalls and Caveats

• Underdosing or premature discontinuation of therapy may lead to treatment failure or recurrence 3
• Failure to consider local resistance patterns when selecting empiric therapy could lead to treatment failure 3
• The risk of anaphylactic reaction to penicillin is approximately 5 cases per 10,000 treatments, which can have severe consequences 8
• GBS UTIs may be more common in women aged 25-34 years and during winter months (December and January), which may influence clinical suspicion 1, 4