Perianal Streptococcal Dermatitis
Definition
Bacterial infection of the perianal skin caused by Streptococcus pyogenes (Group A Streptococcus)
Primarily affects young children, with rare occurrence in adults
Presents as a sharply demarcated erythematous rash around the anus
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Presentation
Bright red, well-defined rash around the perianal region
Symptoms include itching, tenderness, burning, and pain during defaecation
May be associated with mucoid or purulent discharge and minor bleeding
Often follows a recent episode of streptococcal pharyngitis or skin infection
Can be accompanied by perineal discomfort and, in some cases, mild systemic symptoms
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Differential Diagnosis
Pinworms: Rule out with a tape test if perianal itching is prominent
Candidiasis: Common in infants, characterised by satellite lesions and a red rash
Irritant dermatitis: Due to soaps, wipes or poor hygiene
Contact dermatitis: Reaction to topical agents or detergents
Other bacterial infections: Consider if atypical features are present
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Diagnosis
Perianal swab for bacterial culture and sensitivity (MCS) to confirm Group A Streptococcus
Clinical examination focusing on the distribution and character of the rash
Rule out alternative causes such as fungal infection or irritant dermatitis through history and appropriate tests
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Management
Antibiotic Therapy
Oral cephalexin at 25 mg/kg up to a maximum of 1 g, administered twice daily for 5–10 days depending on severity
In cases of penicillin allergy, consider clindamycin or azithromycin with specialist advice
Supportive Measures
Gentle cleansing of the perianal area with warm water and soap-free cleansers
Application of a barrier cream, such as zinc oxide, to protect the skin
Follow-Up
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Prevention
Educate caregivers on the importance of regular handwashing and proper perianal hygiene
Advise on thorough cleaning after defaecation to minimise residual bacterial contamination
Treat symptomatic household members with strep infections to prevent recurrence
Encourage prompt medical review for any new or worsening perianal symptoms
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Additional Notes
Early recognition and treatment are essential to prevent complications such as secondary bacterial infection
The condition may mimic other perianal dermatoses, so a high index of suspicion is required
Reinforce that perianal streptococcal dermatitis is usually self-limiting with appropriate antibiotic therapy
Routine follow-up helps confirm resolution and identify any recurrent or resistant cases promptly
