What are the treatment guidelines for Group A strep (Streptococcus pyogenes) and Group B strep (Streptococcus agalactiae) infections?

Treatment Guidelines for Group A Strep and Group B Strep Infections

For Group A streptococcal (GAS) infections, penicillin remains the treatment of choice due to its proven efficacy, safety, narrow spectrum, and low cost, while Group B streptococcal (GBS) infections in pregnancy require screening between 36-37 weeks with intrapartum antibiotic prophylaxis for colonized women. 1, 2

Group A Streptococcal (GAS) Infections

First-line Treatment Options

• Penicillin V is the drug of choice for GAS pharyngitis: 500 mg orally four times daily for 10 days for adults 1
• Amoxicillin (500 mg three times daily for 10 days) is an acceptable alternative, often preferred for children due to better taste of the suspension 1
• Intramuscular benzathine penicillin G is preferred for patients unlikely to complete a full 10-day oral therapy course 1

Alternative Treatment Options (for penicillin-allergic patients)

• Erythromycin for patients with penicillin allergy 1
• First-generation cephalosporins for patients with non-immediate type hypersensitivity to β-lactams 1
• Clindamycin (300 mg four times daily for 10 days) for patients with erythromycin-resistant GAS who cannot tolerate β-lactams 1
• Azithromycin (500 mg once daily for 3-5 days) is FDA-approved for a shorter course of therapy 1, 3

Management of GAS Carriers

• Streptococcal carriers (asymptomatic individuals with GAS in pharynx) do not ordinarily require antimicrobial therapy 1
• Carriers are at low risk for developing suppurative or non-suppurative complications 1
• For persistent or recurrent GAS colonization, consider the following regimens 1:
  • Clindamycin 300 mg four times daily for 10 days
  • Azithromycin 500 mg once daily for 5 days (sometimes combined with rifampicin)
  • For non-pharyngeal carriage, penicillin alone may not be sufficient 1

Management of Healthcare Workers with GAS

• Healthcare workers with GAS infection should be excluded from clinical work until at least 24 hours of appropriate treatment if asymptomatic 1
• Clearance screens should be taken 24 hours after completing treatment, and again at 1,3,6, and 12 weeks 1
• For eradication failure, consider screening household contacts and pets as potential sources of reinfection 1

Group B Streptococcal (GBS) Infections

Screening and Prevention

• Universal screening for GBS colonization is recommended between 36 0/7 and 37 6/7 weeks of gestation 2, 4
• Proper specimen collection involves swabbing 2 cm into the vagina and 1 cm into the anus 5
• Patients can perform their own swabs effectively 5

Intrapartum Antibiotic Prophylaxis (IAP) Indications

• Positive vaginal-rectal culture for GBS 2, 4
• GBS bacteriuria during current pregnancy 2, 4
• History of a previous infant with invasive GBS disease 2, 4
• Unknown GBS status at labor onset with risk factors:
  • Delivery at <37 weeks' gestation
  • Rupture of membranes ≥18 hours
  • Intrapartum fever ≥38.0°C 2, 4

IAP Regimens

• First-line: Intravenous penicillin 6, 2, 4
• Alternatives: Ampicillin or cefazolin 6
• For significant penicillin allergy: Clindamycin or vancomycin 6
• Penicillin allergy testing is recommended during pregnancy to confirm true allergies 6

Important Clinical Considerations

• IAP is highly effective in preventing early-onset GBS disease but does not prevent late-onset disease 6
• GBS-positive patients with preterm premature rupture of membranes after 34 weeks are not candidates for expectant management due to higher rates of neonatal infectious complications 5
• Although a shorter duration of intrapartum antibiotics is less effective than 4 or more hours, even 2 hours of antibiotic exposure reduces GBS vaginal colony counts 2
• Obstetric interventions should not be delayed solely to provide 4 hours of antibiotic administration before birth 2

Common Pitfalls and Caveats

• Routine testing of asymptomatic household contacts of GAS pharyngitis patients is not recommended except in specific situations with increased risk of frequent infections 1
• Routine post-treatment testing for GAS is not necessary for asymptomatic individuals 1
• Despite screening and IAP protocols, GBS remains a significant cause of neonatal sepsis, requiring continued vigilance 5
• Adherence to GBS management protocols remains suboptimal in many settings, highlighting the need for better integration of obstetric and neonatal care 7
• For recurrent GAS infections, consider tonsillectomy only for patients whose symptomatic episodes do not diminish in frequency over time 1