What is the treatment for perianal streptococcal infection?

Treatment of Perianal Streptococcal Infection

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

Diagnosis

• Perianal streptococcal infection presents with:

  • Sharply demarcated perianal erythema
  • Edematous perianal skin
  • Superficial fissuring when parting the buttocks
  • Pain with defecation
  • Perianal itching and discomfort

• Confirmation requires a perianal swab for culture or rapid strep test specifically requesting Group A beta-hemolytic streptococci (GABHS) testing

First-Line Treatment Options

For patients without penicillin allergy:

• 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

• Oral amoxicillin (often preferred for children due to better taste):

  • 40-50 mg/kg/day divided into 3 doses for 10 days (maximum 1,000 mg/day)
  • Alternative: 25 mg/kg twice daily (maximum 500 mg per dose) 1, 2

• Intramuscular benzathine penicillin G (for patients unlikely to complete oral therapy):

  • <60 lbs (27 kg): 600,000 units as single dose
  • ≥60 lbs: 1,200,000 units as single dose 1, 2

Alternative Treatment Options (Penicillin Allergy)

For patients with non-anaphylactic penicillin allergy:

• Cephalexin: 20 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1, 2

For patients with anaphylactic penicillin allergy:

• Clindamycin: 7 mg/kg three times daily (maximum 300 mg per dose) for 10 days 1, 2, 3
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1, 2
• Clarithromycin: 7.5 mg/kg twice daily (maximum 250 mg per dose) for 10 days 1, 2

Treatment Duration

• A full 10-day course of antibiotics is essential to eradicate the organism and prevent complications, even if symptoms resolve earlier 1, 4
• For azithromycin, a 5-day course is sufficient 1, 2
• Some research suggests that perianal streptococcal dermatitis may require a longer treatment duration (14-21 days) to ensure complete eradication 5

Adjunctive Therapy

• Topical antiseptics or antibiotics may be added to systemic treatment:
  • Mupirocin 2% ointment applied three times daily for 10 days 6
  • Bacitracin-containing ointment 7

Follow-up

• Clinical follow-up is recommended to ensure resolution of symptoms
• Consider post-treatment perianal swab to confirm eradication, especially in cases of recurrence or persistent symptoms 5
• Monitor for post-streptococcal complications, including urine analysis to check for post-streptococcal glomerulonephritis 5

Special Considerations

• Perianal streptococcal infection is more common in children but can occur in adults 8, 9
• In adults, Group B streptococci are more commonly implicated than Group A 8
• Prior treatment with topical antifungals, corticosteroids, or pinworm medications often fails to improve or worsens symptoms 6
• The condition is often misdiagnosed, leading to delayed treatment and prolonged discomfort 5, 9

Treatment Pitfalls to Avoid

• Failing to obtain a perianal swab for proper diagnosis
• Treating empirically for other conditions (fungal infection, hemorrhoids) without ruling out streptococcal infection
• Discontinuing antibiotics prematurely when symptoms improve
• Not considering perianal streptococcal infection in the differential diagnosis of perianal erythema and discomfort in both children and adults