Capsular types and antibiotic susceptibility of invasive Streptococcus pneumoniae among children in Sweden

To investigate the serotype distribution and antibiotic susceptibility patterns 204 isolates of Streptococcus pneumoniae obtained from blood or cerebrospinal fluid (CSF) of children less than or equal to18 y of age were collected from 19 clinical microbiological laboratories in Sweden during the years 1998-2001. 166 isolates were from blood only, and 38 isolates were from CSF. The most common serotypes found were 6B, 1, 7F, 14, 18C, 19F, 6A, 4, 23F, 9V and 19A, in descending order of frequency. During the study period serotype 6B increased in frequency from 14.3% in 1998 to 28.3% in 2001 and serotype 1 decreased simultaneously from 20.4% to 9.4%. Serotype 1 was the most common serotype among children greater than or equal to2 y of age or older, but was not found among children <2 y of age. The potential coverage rate for the heptavalent pneumococcal conjugate vaccine varied between 53 and 68% during the studied years, and was higher for children <2 y of age (74%) than for older children (51%). The majority of isolates were susceptible to penicillin and other antibiotics tested.