Sequential colonization by Streptococcus pneumoniae of healthy children living in an orphanage

A prospective study of nasopharyngeal colonization by Streptococcus pneumon iae in the exceptional conditions of a closed community of abandoned childr en was done over a 1-year period; 71 children (age <24 months) were studied monthly. S. pneumoniae was isolated from 58 (81.7%), and 94.5% of the 111 isolates were resistant to penicillin. The mean rate of carriage was estima ted at 57.4%, ranging from 42.8% to 70.4%. Children were sequentially colon ized by a mean of 3 different isolates. The mean duration of carriage for a given isolate was similar to 2.2 months, Serotyping and molecular typing b y pulsed-held gel electrophoresis showed that children were colonized by a limited number of clones belonging to only 4 serotypes and 4 pulsotypes. Th ese clones rapidly spread in the community and colonized the children in wa ves, with a rapid turnover of S. pneumoniae isolates, facilitated by close contact between children.