What are the treatment options for strep infections with suspected antibiotic resistance?

Treatment Options for Antibiotic-Resistant Streptococcal Infections

For streptococcal infections with suspected antibiotic resistance, clindamycin is the most effective treatment option due to its low resistance rate of approximately 1% among Group A Streptococcus (GAS) isolates in the United States. 1

First-Line Treatment Options

• Penicillin and amoxicillin remain the drugs of choice for GAS pharyngitis in non-allergic patients, as penicillin-resistant GAS has never been documented anywhere in the world 1
• For patients with suspected treatment failure on penicillin:
  • Clindamycin is recommended due to its very low resistance rate (approximately 1%) 1
  • Narrow-spectrum cephalosporins such as cefadroxil or cephalexin for 10 days are effective alternatives 1

Treatment Algorithm Based on Previous Antibiotic Exposure

For patients with penicillin/amoxicillin treatment failure:

1. First option: Clindamycin

   • Dosage: Adults and children >30kg: 300-450 mg orally three times daily for 10 days 1
   • Children: 20 mg/kg/day divided in 3 doses for 10 days 2
   • Advantages: Low resistance rate (1%), effective against most strains 1

2. Second option: Narrow-spectrum cephalosporins

   • Cefadroxil or cephalexin for 10 days 1
   • These are preferred over broad-spectrum cephalosporins to minimize selection of resistant flora 1

For Penicillin-Allergic Patients

• For patients with immediate (anaphylactic-type) hypersensitivity to penicillin:

  • Clindamycin for 10 days 1, 2
  • Macrolides (clarithromycin for 10 days or azithromycin for 5 days) 1, 2
    • Note: Macrolide resistance rates among GAS in the US are around 5-8% 1, 2

• For patients with non-anaphylactic penicillin allergy:

  • Cephalosporins (cefadroxil or cephalexin) for 10 days 1, 2
  • Note: Up to 10% of penicillin-allergic patients may also be allergic to cephalosporins 1

Important Considerations

• Macrolide resistance (erythromycin, clarithromycin, azithromycin) among GAS isolates in the US is approximately 5-8%, which can result in treatment failures 1
• Tetracyclines should not be used due to high prevalence of resistant strains 1
• Sulfonamides and trimethoprim-sulfamethoxazole are ineffective against GAS and should not be used 1
• Older fluoroquinolones (e.g., ciprofloxacin) have limited activity against GAS 1
• Newer fluoroquinolones (e.g., levofloxacin, moxifloxacin) are active against GAS but are expensive and have unnecessarily broad spectrum 1

Duration of Therapy

• Standard treatment duration is 10 days for most antibiotics to achieve maximal pharyngeal eradication of GAS 1
• Exceptions include azithromycin, which is given for 5 days due to its prolonged tissue half-life 1, 2
• Short-course cephalosporin therapy (5 days) is not recommended due to lack of definitive evidence 1

Adjunctive Therapy

• Acetaminophen or NSAIDs (e.g., ibuprofen) are recommended for symptom relief 1
• Avoid aspirin in children due to risk of Reye syndrome 1
• Corticosteroids are not recommended as adjunctive therapy 1

Monitoring and Follow-Up

• Routine post-treatment testing is not recommended unless the patient is at high risk for acute rheumatic fever or has recurrence of symptoms 1
• Testing or treatment of asymptomatic household contacts is not routinely recommended 1

Common Pitfalls to Avoid

• Do not use tetracyclines, sulfonamides, or trimethoprim-sulfamethoxazole for GAS infections 1
• Do not use fluoroquinolones as first-line therapy due to their broad spectrum and high cost 1
• Do not routinely test for cure after completing antibiotic therapy 1
• Be aware that some penicillin treatment failures may be due to poor compliance with the 10-day regimen rather than true resistance 3