What is the treatment for perianal dermatitis caused by Group B Streptococci (GBS)?

Treatment of Perianal Dermatitis Caused by Group B Streptococci

The recommended treatment for perianal dermatitis caused by Group B Streptococci (GBS) is oral penicillin or amoxicillin for 14 days, with alternative options for penicillin-allergic patients based on susceptibility testing. 1

First-Line Treatment Options

• For non-allergic patients, penicillin is the preferred agent due to its narrow spectrum of activity, administered as penicillin G 5 million units IV initially, then 2.5 million units IV every 4 hours for inpatient cases 2
• For outpatient treatment, oral amoxicillin for 14 days is effective in resolving GBS perianal dermatitis 1
• Complete the full prescribed duration of treatment to ensure complete eradication and prevent recurrence 3

Treatment for Penicillin-Allergic Patients

• For patients with penicillin allergy who are not at high risk for anaphylaxis (no history of anaphylaxis, angioedema, respiratory distress, or urticaria), cefazolin or cephalexin is the preferred alternative 2, 4, 3
• For patients at high risk for anaphylaxis, treatment options include:
  • Clindamycin 900 mg IV every 8 hours (or oral equivalent for outpatients), but only if the isolate is confirmed susceptible 2, 4
  • Vancomycin 1 g IV every 12 hours for patients with severe infection or when susceptibility results are unavailable 2, 4

Importance of Susceptibility Testing

• Susceptibility testing should be performed on GBS isolates from penicillin-allergic patients at high risk for anaphylaxis 4
• Testing for inducible clindamycin resistance is necessary for isolates that are susceptible to clindamycin but resistant to erythromycin 2, 4
• If an isolate is resistant to erythromycin, it might have inducible resistance to clindamycin even if it appears susceptible 2

Clinical Considerations and Pitfalls

• Diagnosis should be confirmed with bacterial culture from a perianal swab before initiating treatment 1, 5
• While Group A Streptococcus is commonly associated with perianal dermatitis in children, GBS is more frequently found in adult cases 1, 5
• Underdosing or premature discontinuation of therapy may lead to treatment failure or recurrence 3
• Failure to consider local resistance patterns when selecting empiric therapy could lead to treatment failure 3
• In a study of 53 adult patients with perianal streptococcal dermatitis, GBS was the most common causative organism, and a 14-day course of antibiotics was effective in most cases 1

Follow-up Recommendations

• Consider post-treatment swab to confirm eradication of the organism, especially in recurrent or severe cases 1
• No routine follow-up testing is required if symptoms resolve completely 3
• Be aware that some patients may require continuing treatment for another underlying anorectal condition (58% in one study) 1