Antibiotic-resistant pneumococci carried by young children do not appear to disseminate to adult members of a closed community

Although antibiotic-resistant pneumococci have been frequently detected amo ng day care center (DCC) attendees, the transmission of these organisms to other members of the community has not been adequately studied. Nasopharyng eal cultures were obtained from 152 children and 244 adult members of a clo sed community (a kibbutz) in Israel. Serotyping, antibiogram, and pulsed-fi eld gel electrophoresis were performed to determine the relatedness of isol ated pneumococci. Twenty (30%) of the 66 isolates from children showed decr eased susceptibility to penicillin and 9 isolates (14%) were resistant to g reater than or equal to3 drugs. Of the 16 isolates from adults, 5 (31%) wer e intermediately resistant to trimethoprim-sulfamethoxazole. Resistant stra ins carried by DCC attendees were not isolated either from their parents or from other adult members of the community. Despite the high degree of inte rpersonal contact occurring in a closed community, resistant pneumococcal s trains carried by DCC attendees do not appear to be easily transmitted to t he adult population, which suggests the existence of an immunological barri er.