What are oral alternatives for treating a Urinary Tract Infection (UTI) caused by Group B Streptococcus (GBS)?

Oral Antibiotic Options for UTI Caused by Group B Streptococcus (GBS)

For urinary tract infections caused by Group B Streptococcus (GBS), nitrofurantoin is the preferred first-line oral treatment option due to its high efficacy and low resistance rates. 1

First-Line Treatment Options

• Nitrofurantoin: 100 mg twice daily for 5-7 days
  • Excellent sensitivity profile (95.5% susceptibility) 1
  • Specifically recommended for GBS bacteriuria 2
  • Low resistance rates compared to other oral options

Second-Line Treatment Options (for penicillin-allergic patients)

1. Amoxicillin/Ampicillin: 500 mg three times daily for 5-7 days

   • High efficacy against GBS (96% susceptibility) 1
   • However, some studies show increasing resistance (up to 81.6% in some populations) 3

2. Cephalexin: 500 mg four times daily for 5-7 days

   • Effective for patients without immediate hypersensitivity to β-lactams
   • First-generation cephalosporins show good activity against GBS 4
   • Appropriate for dialysis patients at 500 mg after each dialysis session 5

Third-Line Treatment Options

1. Norfloxacin/Fluoroquinolones: 400 mg twice daily for 5-7 days

   • High susceptibility rates (96.9%) 1
   • Use with caution due to risk of neuropathy and other adverse effects 5

2. Clindamycin: 300-450 mg every 6 hours for 7-10 days

   • Consider only after susceptibility testing due to increasing resistance (23.3-26%) 6, 3, 7
   • Appropriate for patients with severe penicillin allergy 4

Important Considerations

• Always obtain urine culture before initiating antibiotics to guide therapy
• Susceptibility testing is crucial, especially for penicillin-allergic patients, due to increasing resistance patterns 2
• Avoid tetracycline and co-trimoxazole due to high resistance rates (81.6% and 68.9% respectively) 1
• Avoid azithromycin due to high resistance rates (31-44.5%) 7, 2
• Seasonal variations may affect prevalence, with higher rates in winter months (December-January) 1

Special Populations

• For pregnant women: Consult with obstetrics as different protocols apply for GBS during pregnancy 4
• For patients with renal impairment: Adjust dosing according to creatinine clearance; cephalexin 500 mg after each dialysis session is appropriate 5
• For elderly patients or those with chronic conditions: Consider underlying urinary tract abnormalities, which are common (60%) in patients with GBS UTI 8

Follow-up Recommendations

• Assess clinical response within 48-72 hours of initiating therapy
• Consider follow-up urine culture 1-2 weeks after completing treatment if symptoms persist
• Screen for urinary tract abnormalities in patients with GBS UTI, as they are frequently present 8

Remember that resistance patterns can vary geographically and over time, so local antibiogram data should be considered when available. The high prevalence of multidrug-resistant GBS isolates (33.6% in some studies) underscores the importance of susceptibility testing 7.