Perianal streptococcal dermatitis. The possible protective role of alpha-streptococci against spread and recurrence of group A streptococcal throat infection

Objective - To follow the spread of beta-haemolytic streptococci group A (GAS) within a family and examine the protective activity of normally occurring alpha-streptococci against GAS tonsillitis. Design - Follow up of recurrent GAS throat infection within a family. Setting - Intra familial spread of GAS. Patients - A family of four, the mother suffering from recurrent streptococcal tonsillitis and a son with perianal streptococcal dermatitis. Results - The strain of the GAS found in the perianal region of the boy was identical with that found in the throat of his mother. She had recurrent streptococcal tonsillitis, while the boy remained healthy in the throat. She lacked interfering alpha-streptococci in the throat, while the boy had a massive growth of alpha-streptococci in his throat with capacity to inhibit the growth of the streptococcal isolate. Main outcome measures - Infection with GAS within a family correlated with the growth-inhibiting activity of the alpha-streptococci in vitro. Conclusions - The study demonstrated the spread of GAS from a patient with streptococcal dermatitis to the throat of another person within the family, and the hindrance of induction of infection in patients carrying interfering alpha-streptococci.