Factors influencing Streptococcus pneumoniae carriage

Streptococcus pneumoniae is carried nasopharyngeally by 20 %-40 % of healthy children. But this rate of carriage is highly variable. Several risk factors have been associated with Streptococcus pneumoniae carriage, including day care center attendance, the size of the day care center, living in close contact as siblings, and socioeconomic factors. The antimicrobial treatment increases the percentage of penicillin-resistant Streptococcus pneumoniae. We report a prospective study on nasopharyngeal carriage of Streptococcus pneumoniae performed during a 1-year period in children living in an orphanage representing an extreme version of the situation of a day care center; 71 children (<24 months) were studied monthly. The mean rate of carriage was 574 % ranging from 42.8 % to 70.4 %, and 94.5 % of the isolates were resistant to penicillin, Children were sequentially colonized by a mean of 3 different isolates. Serotyping and molecular typing showed that children were colonized by a limited number of clones which rapidly spread in the community and colonized children in waves with a rapid turnover. (c) 2002 Editions scientifiques et medicales Elsevier SAS.