What is the treatment for a perianal rash caused by Streptococcus A (Group A Streptococcus)?

Treatment of Perianal Rash Caused by Streptococcus A

Oral penicillin or amoxicillin for 10 days is the first-line treatment for perianal streptococcal dermatitis, with clindamycin as the preferred alternative for penicillin-allergic patients. 1

Clinical Presentation

Perianal streptococcal dermatitis presents as:

• Bright red, sharply demarcated perianal rash 2
• Perianal itching and rectal pain 2
• Blood-streaked stools (in approximately one-third of patients) 2
• Painful defecation 3

Diagnosis

• Rapid streptococcal test of the perianal area is recommended to confirm diagnosis 2
• Bacterial culture from a perianal swab is an alternative diagnostic method 3

Treatment Algorithm

First-Line Treatment (Non-Allergic Patients)

1. Oral Penicillin V:

   • Children: 250 mg 2-3 times daily for 10 days
   • Adults: 250 mg 4 times daily or 500 mg twice daily for 10 days 1

   OR

2. Oral Amoxicillin:

   • 40-50 mg/kg/day divided into 3 doses for 10 days (maximum 1,000 mg/day) 1
   • Complete the full 10-day course even if symptoms resolve earlier 4

3. Alternative for Compliance Issues:

   • Intramuscular benzathine penicillin G: 600,000 units for children <60 lbs (27 kg) or 1,200,000 units for ≥60 lbs, single dose 1

For Penicillin-Allergic Patients

1. Non-anaphylactic Penicillin Allergy:

   • Cephalexin: 20 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1

2. Anaphylactic Penicillin Allergy:

   • Clindamycin: 8-16 mg/kg/day divided into 3-4 doses for 10 days (for children)
   • Adults: 150-300 mg every 6 hours for 10 days 1, 5

   OR

   • Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1
   • Clarithromycin: 7.5 mg/kg twice daily (maximum 250 mg per dose) for 10 days 1

Important Treatment Considerations

• A full 10-day course of antibiotics is essential to eradicate the organism and prevent complications, even if symptoms resolve earlier 1
• For streptococcal infections, therapy must be sufficient to eliminate the organism (10-day minimum); otherwise, sequelae of streptococcal disease may occur 6
• Follow-up is necessary because recurrences are common 2, 3
• In case of relapse, a first or second-generation cephalosporin may be considered 3

Special Considerations

• While perianal streptococcal dermatitis is most common in children between 6 months and 10 years of age, it can occasionally occur in adults 7
• Staphylococcus aureus can also cause perianal dermatitis, particularly if satellite pustules are present. In such cases, penicillin VK alone will not be effective 8
• Screening for affected persons in contact with the patient is indicated as perianal streptococcal dermatitis is known to be highly contagious 3

Pitfalls to Avoid

1. Misdiagnosis: Perianal streptococcal dermatitis is often misdiagnosed as pinworm infection (enterobiasis), hemorrhoids, or fungal infection, leading to inappropriate treatment 2, 7

2. Inadequate Treatment Duration: Failing to complete the full 10-day course of antibiotics can lead to treatment failure and recurrence 1, 6

3. Overlooking Complications: Although rare, complications such as deep infection or abscess formation can occur 7

4. Neglecting Follow-up: Given the high rate of recurrence, follow-up evaluation is essential 2, 3

By following this treatment algorithm, clinicians can effectively manage perianal streptococcal dermatitis and minimize the risk of complications and recurrence.