What antibiotic regimen is suitable for a UTI caused by Beta hemolytic Streptococcus, group B?

Treatment of UTI Caused by Beta Hemolytic Streptococcus Group B

For a UTI caused by Group B Streptococcus (GBS), penicillin-based antibiotics are the first-line treatment, with amoxicillin 500 mg three times daily for 10 days being the recommended regimen. 1

First-Line Treatment Options

Penicillin-Based Options (Preferred)

• Amoxicillin: 500 mg three times daily for 10 days 1
• Penicillin V: 500 mg four times daily for 10 days 1

These options are supported by high-quality evidence from randomized controlled trials and are recommended by the World Health Organization (WHO) for GBS urinary tract infections 1.

Alternative Options for Penicillin-Allergic Patients

Non-Anaphylactic Penicillin Allergy

• Cefazolin: For patients with non-severe penicillin allergy (no history of anaphylaxis, angioedema, respiratory distress, or urticaria) 2

Severe Penicillin Allergy (History of Anaphylaxis)

• Clindamycin: 300 mg four times daily for 10 days 1, 3

  • Note: Clindamycin should only be used if the GBS isolate is confirmed susceptible to both clindamycin and erythromycin through antimicrobial susceptibility testing 2
  • Warning: If significant diarrhea occurs during therapy, discontinue clindamycin due to risk of C. difficile colitis 3

• Vancomycin: Should be used if the GBS isolate is resistant to clindamycin or if susceptibility is unknown 2

Treatment Considerations

Resistance Patterns

• Increasing resistance patterns have been reported for GBS:
  • Penicillin resistance: up to 18.3%
  • Ampicillin resistance: up to 81.6%
  • Clindamycin resistance: up to 26.6% 1

Duration of Treatment

• Standard duration is 10 days for GBS UTIs 1
• For β-hemolytic streptococcal infections, treatment should continue for at least 10 days to ensure complete eradication 3

Follow-Up

• 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 Management

If initial treatment fails:

1. If penicillin was used initially, switch to clindamycin 300 mg four times daily for 10 days (if susceptible) 1
2. Consider combination therapy options such as:
   • Penicillin plus rifampicin
   • Clindamycin with rifampicin 1

Special Considerations

Bacteremia Risk

Recent research suggests that for beta-hemolytic streptococcal bloodstream infections, intravenous antibiotics may be superior to oral therapy 4. If there are signs of systemic infection (fever, chills, hypotension), consider initial intravenous therapy before transitioning to oral antibiotics.

Pregnancy

If the patient is pregnant, note that GBS bacteriuria at any point during pregnancy requires intrapartum antibiotic prophylaxis during labor 1.

Conclusion

For uncomplicated UTIs caused by Group B Streptococcus, amoxicillin 500 mg three times daily for 10 days is the recommended first-line treatment. For penicillin-allergic patients, clindamycin is an appropriate alternative if the isolate is susceptible. Follow-up cultures are essential to confirm eradication of the infection.