Background: Perianal group A streptococcal infection (PASI) occurs primarily in children. There is limited information on the incidence, transmission and treatment of PASI. We report a cluster of cases connected to a Danish kindergarten and observations of the incidence of PASI in the local population.
Setting: A Danish rural community with 1765 children 15 years and younger registered with two general practice clinics.
Methods: After being alerted of a possible cluster of PASI cases, all isolates of group A beta-hemolytic streptococci were collected and subjected to T typing and pulsed field gel electrophoresis (PFGE) if grown from either a rectal swab or an accompanying throat swab obtained in the offices of local general practitioners during the ensuing 4-month period. Clinical data were obtained from the files of the local general practitioners.
Results: Twelve cases of PASI were caused by group A beta-hemolytic streptococci T type 28 with an identical PFGE profile: 6 of the cases were in children attending the same kindergarten, 4 were connected otherwise to the cluster and 2 cases seemed to be unrelated. Five cases of PASI with different T types and PFGE profiles were diagnosed during the same period giving an estimated annual incidence of 2 to 7 per 1000 children. Penicillin V was ineffective in 3 cases, and no recurrence was seen after change of the treatment to oral clarithromycin.
Conclusions: A clone of T type 28 seemed to be the cause of the largest cluster of PASI cases described thus far. Clarithromycin was effective as second line treatment. An estimated annual baseline incidence of 2 to 7 per 1000 in the local population indicates that PASI may not be as rare as previously estimated.