What is the treatment for Group B Streptococcus (GBS) infections?

Treatment for Group B Streptococcus (GBS) Infections

Penicillin G is the first-line treatment for Group B Streptococcus infections, with specific alternatives for penicillin-allergic patients based on susceptibility testing. 1, 2

First-Line Treatment Options

Non-Pregnant Adults with GBS Infections

• Penicillin G: 5 million units IV initially, then 2.5 million units IV every 4 hours until resolution 2
• Ampicillin: 2 g IV initially, then 1 g IV every 4 hours (acceptable alternative but penicillin G preferred due to narrower spectrum) 3
• Oral options for less severe infections:
  • Penicillin V: 500 mg four times daily for 10 days
  • Amoxicillin: 500 mg three times daily for 10 days 1

Penicillin-Allergic Patients

• Low risk of anaphylaxis: Cefazolin 2 g IV initially, then 1 g IV every 8 hours 3, 1
• High risk of anaphylaxis:
  • Clindamycin 300 mg four times daily for 10 days (only if GBS isolate confirmed susceptible) 1
  • Vancomycin (if GBS isolate resistant to clindamycin or susceptibility unknown) 1

Important: Erythromycin is no longer recommended due to increasing GBS resistance (up to 32.8%) 3, 4

Treatment Based on Infection Type

Invasive GBS Disease

• Bacteremia/Sepsis: Penicillin G 24 million units/day divided every 4 hours for 10-14 days 2
• Meningitis:
  • Adults: 24 million units/day as 2 million units every 2 hours 2
  • Children: 250,000 units/kg/day in equal doses every 4 hours for 10-14 days 2
• Endocarditis: 12-20 million units/day for 4 weeks 2

Urinary Tract Infections

• First-line: Penicillin or amoxicillin for 10 days 1
• Alternatives: Amoxicillin-clavulanic acid, nitrofurantoin, or sulfamethoxazole-trimethoprim (consider local resistance patterns) 1

Special Populations

Pregnant Women

• GBS bacteriuria during pregnancy: Requires treatment at time of diagnosis AND intrapartum antibiotic prophylaxis during labor 1, 5
• Intrapartum prophylaxis regimen:
  • Penicillin G: 5 million units IV initial dose, then 2.5-3.0 million units IV every 4 hours until delivery 1
  • Ampicillin: 2 g IV initial dose, then 1 g IV every 4 hours until delivery 1

Neonates and Infants

• Early-onset disease: Ampicillin with an aminoglycoside for infants up to 7 days of age 3
• Late-onset disease: Evaluation should include blood, urine, and cerebrospinal fluid cultures; cerebrospinal fluid analysis; and inflammatory markers 3
• Dosing for serious infections: 150,000-300,000 units/kg/day of penicillin G divided in equal doses every 4-6 hours 2

Monitoring and Follow-up

• Clearance cultures should be taken 24 hours after completing treatment 1
• Additional follow-up cultures at 1,3,6, and 12 weeks are recommended to ensure complete eradication 1
• For most acute infections, treatment should continue for at least 48-72 hours after the patient becomes asymptomatic 2

Antibiotic Resistance Considerations

• GBS remains universally susceptible to beta-lactam antibiotics, though there have been reports of reduced susceptibility in some countries 6
• Resistance to second-line antibiotics is increasing:
  • Clindamycin resistance: 12.7% and rising (increased from 10.5% to 15.0%) 4
  • Erythromycin resistance: 25.6% and rising (increased from 15.8% to 32.8%) 4
• Vancomycin remains effective with only two documented cases of resistance 6

Important Caveats

• Oral antimicrobial agents should not be used to treat GBS colonization during pregnancy as this is not effective in eliminating carriage or preventing neonatal disease 3
• When treating GBS infections, ensure adequate duration of therapy (10 days for most infections, longer for endocarditis and other severe infections) 1, 2
• Consider local antibiotic resistance patterns when selecting therapy, particularly for second-line agents 1