What is the treatment for a rash that occurs after a streptococcal (strep) infection?

Treatment of Rash After Streptococcal Infection

Rash occurring after a streptococcal infection should be treated with appropriate antibiotics directed against Gram-positive bacteria, particularly penicillin or amoxicillin for 10 days, unless there are contraindications such as penicillin allergy. 1, 2

Antibiotic Treatment Options

First-line therapy:

• For non-penicillin allergic patients:
  • Penicillin V: 250 mg 3-4 times daily or 500 mg twice daily for 10 days 2
  • Amoxicillin: 40-50 mg/kg/day divided into 3 doses for 10 days (maximum 1,000 mg/day) - preferred in young children due to better taste acceptance 2
  • Benzathine penicillin G: 1.2 million units as a single intramuscular dose (for patients unlikely to complete oral therapy) 2

For penicillin-allergic patients:

• Non-anaphylactic allergy:
  • First-generation cephalosporins (e.g., cephalexin) for 10 days 1, 2
• Anaphylactic allergy:
  • Clindamycin for 10 days 1, 2
  • Clarithromycin for 10 days 1, 2
  • Azithromycin for 5 days 1, 2

Types of Post-Streptococcal Rashes

1. Impetigo:

   • Highly contagious bacterial infection of superficial epidermis layers
   • Characterized by discrete purulent lesions
   • Treatment: Topical mupirocin for limited lesions; oral antibiotics for numerous or non-responding lesions 1

2. Erysipelas:

   • Fiery red, tender, painful plaque with well-demarcated edges
   • Usually caused by Streptococcus pyogenes
   • Treatment: Penicillin (oral or parenteral depending on severity) 1

3. Cellulitis:

   • Acute bacterial infection of dermis and subcutaneous tissue
   • Causes local signs of inflammation (warmth, erythema, pain, lymphangitis)
   • Treatment: Penicillinase-resistant semisynthetic penicillin or first-generation cephalosporin 1

4. Petechial rash after Group A streptococcal pharyngitis:

   • Can occur as a post-infectious phenomenon
   • Treatment: Complete the full course of antibiotics for the underlying streptococcal infection 1

Adjunctive Therapy

• Analgesics/antipyretics (acetaminophen or NSAIDs) for symptomatic relief of moderate to severe symptoms or high fever 2
• Avoid aspirin in children due to risk of Reye syndrome 2
• Warm compresses and cleansing with antibacterial agents may help with skin lesions 3
• Removal of crusts for better penetration of topical agents 3

Treatment Duration and Follow-up

• Complete the full 10-day course of antibiotics to eradicate the organism and prevent complications, even if symptoms resolve earlier (exception: 5-day course for azithromycin) 2
• Follow-up is necessary as recurrences are common (approximately 20% of cases) 2
• Routine post-treatment testing is not recommended unless symptoms persist 1, 2

Special Considerations

• For treatment failures, consider switching to a broader-spectrum agent like clindamycin 2
• Testing or treating asymptomatic household contacts is not routinely recommended 1, 2
• In children <3 years, testing is generally not recommended unless they have risk factors (e.g., older sibling with strep throat) 1, 2

Clinical Pearls and Pitfalls

• Distinguish between post-streptococcal rash and other exanthems by considering:

  • Timing relative to onset of fever
  • Distribution pattern
  • Progression of rash
  • Associated symptoms 1

• Be aware that some post-streptococcal rashes may be immune-mediated rather than directly infectious, but completing antibiotic treatment is still important to prevent complications 1

• For complex or recurrent cases, consider the possibility of a carrier state with intercurrent viral infection rather than treatment failure 1