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

Treatment of Group B Streptococcus Urinary Tract Infection

For Group B Streptococcus (GBS) urinary tract infections, penicillin is the first-line treatment, with amoxicillin as an effective alternative based on high-quality evidence from clinical guidelines. 1

First-Line Treatment Options

Penicillin-Based Regimens (Preferred)

• Penicillin V: 500 mg orally four times daily for 10 days 1
• Amoxicillin: 500 mg orally three times daily for 10 days 1
• Ampicillin: 2 g IV initial dose, then 1 g IV every 4 hours (for severe infections) 1

For Penicillin-Allergic Patients

• Clindamycin: 300 mg orally four times daily for 10 days 1
  • Note: Recent studies show increasing clindamycin resistance (up to 77.34%) 2
• Cefazolin: 2 g IV initial dose, then 1 g IV every 8 hours (for patients with non-anaphylactic penicillin allergy) 1

Treatment Algorithm Based on Infection Severity

Non-Severe UTI (Uncomplicated)

1. First choice: Penicillin V or amoxicillin for 10 days
2. Penicillin allergy: Clindamycin (if susceptible) for 10 days
3. Alternative options:
   • Amoxicillin-clavulanic acid
   • Nitrofurantoin
   • Sulfamethoxazole-trimethoprim (if susceptible) 1

Severe UTI/Pyelonephritis

1. First choice: IV ampicillin or penicillin G
2. Penicillin allergy: IV clindamycin (if susceptible) or vancomycin
3. Step-down therapy: Once clinical improvement occurs, transition to oral therapy to complete 10-14 days total 1

Special Considerations

Antibiotic Resistance Patterns

• Recent studies show 100% sensitivity to penicillin, ampicillin, and vancomycin for GBS 2
• High resistance rates to:
  • Clindamycin (77.34%)
  • Tetracycline (88.46%) 2
• Always consider local resistance patterns when selecting antibiotics

Follow-up Recommendations

• Clearance cultures should be taken 24 hours after completing treatment
• Additional follow-up cultures at 1,3,6, and 12 weeks are recommended to ensure complete eradication 1

Treatment Failure

If initial treatment fails:

1. Switch to clindamycin if penicillin was used initially (if susceptible)
2. Consider combination therapy such as penicillin plus rifampicin 1, 3
3. Investigate for anatomical abnormalities or other complicating factors
4. Check for potential reservoirs of infection (vagina, urethra, gastrointestinal tract) 3

Pregnant Women with GBS UTI

• All pregnant women with GBS bacteriuria at any point during pregnancy require intrapartum antibiotic prophylaxis (IAP) during labor 1, 4
• GBS bacteriuria in pregnancy (regardless of colony count) is an indication for IAP 4
• No need for repeat screening in the third trimester if GBS bacteriuria was previously documented 4

Pitfalls and Caveats

• Failure to recognize GBS as a significant UTI pathogen, especially in women of childbearing age
• Not considering local resistance patterns when selecting antibiotics
• Inadequate follow-up to ensure complete eradication
• Overlooking potential reservoirs of infection that may lead to recurrence
• Failing to provide IAP during labor for pregnant women with history of GBS bacteriuria

GBS UTIs should be treated promptly with appropriate antibiotics to prevent complications and recurrence, with penicillin-based regimens remaining the most effective treatment option based on current evidence.