What is the recommended treatment for perianal cellulitis caused by streptococcal infection in a child?

Treatment of Perianal Streptococcal Cellulitis in Children

Oral amoxicillin at 40 mg/kg/day divided into three doses for 10-14 days is the recommended first-line treatment for perianal streptococcal cellulitis in children. 1, 2

Diagnosis

• Diagnosis should be confirmed by obtaining a perianal swab for culture or rapid streptococcal antigen test
• Rapid streptococcal tests have a positive predictive value of 80% and negative predictive value of 96% compared to culture 3
• Clinical presentation typically includes:
  • Sharply demarcated perianal erythema
  • Perianal pain and itching
  • Painful defecation
  • Rectal bleeding or fissures
  • Possible fecal incontinence 4, 3

First-line Treatment Options

For Children Without Penicillin Allergy:

• Amoxicillin: 40 mg/kg/day divided into three doses for 10-14 days 1, 2
  • Alternative dosing: 50 mg/kg once daily (maximum 1,000 mg) OR 25 mg/kg twice daily (maximum 500 mg per dose) 5
• Penicillin V:
  • Children: 250 mg two or three times daily for 10 days 5
  • It's recommended that treatment for streptococcal infections continue for at least 10 days to prevent acute rheumatic fever 1

For Children With Penicillin Allergy:

• Cephalexin: 20 mg/kg per dose twice daily (maximum 500 mg per dose) for 10 days 5
• Clindamycin: 7 mg/kg per dose three times daily (maximum 300 mg per dose) for 10 days 5
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 5
• Clarithromycin: 7.5 mg/kg per dose twice daily (maximum 250 mg per dose) for 10 days 5

Adjunctive Therapy

• Consider topical mupirocin 2% ointment applied to the affected area three times daily for 10 days as an adjunct to oral antibiotics 2
• Analgesics or antipyretics (acetaminophen, NSAIDs) may be used for pain management 5
• Avoid aspirin in children due to risk of Reye's syndrome 5

Duration of Treatment

• Minimum treatment duration should be 10 days for streptococcal infections 5, 1
• Some experts recommend 14-21 days of treatment to ensure complete eradication and prevent recurrence 6
• Treatment should continue for 48-72 hours beyond symptom resolution 1

Follow-up

• Clinical improvement is typically rapid and dramatic once appropriate antibiotic therapy is initiated 2, 4
• Consider post-treatment perianal swab to confirm microbiological cure 6
• Monitor for post-streptococcal glomerulonephritis with urinalysis 6
• Be aware that recurrences occur in approximately 20% of cases, usually within 3.5 months 3

Common Pitfalls

• Perianal streptococcal cellulitis is often misdiagnosed, with time to diagnosis ≥3 weeks in 65% of cases 3
• Prior inappropriate treatments with antifungals or topical corticosteroids may worsen symptoms 2
• Consider testing for asymptomatic streptococcal throat carriage, which occurs in 63% of cases 3
• The condition may extend to involve the genitals (penis or vulva) and can be misinterpreted as a sign of sexual abuse 7

By following these treatment guidelines, most children with perianal streptococcal cellulitis will experience rapid symptom improvement and complete resolution of the infection.