Nasopharyngeal carriage of bacteria in otitis-prone and non-otitis-prone children in day-care centres.

During a 2-year period nasopharyngeal specimens were taken monthly on scheduled occasions as well as at episodes of acute otitis media (AOM) from a population of children attending day-care centres. The carriage rates of pneumococci, Haemophilus influenzae and Branhamella catarrhalis in 26 otitis-prone (OP) children when asymptomatic and at episodes of AOM were compared with the carriage rates in 36 non-otitis-prone (NOP) children. Pneumococci, H. influenzae and B. catarrhalis were found as frequently in NOP as in asymptomatic OP children. At AOM episodes only B. catarrhalis was found significantly more often than in the scheduled cultures. The frequencies of the six most commonly isolated pneumococcal types/groups (6, 23, 19, 14, 11, 18) were similar in the cultures taken from NOP and OP children on scheduled occasions as well as in cultures taken at AOM episodes. In contrast to the NOP children H. influenzae and B. catarrhalis were isolated less frequently in the 3-4-year-old than in the 2-3-year-old asymptomatic OP children. Our data indicated that the presence of pneumococci, H. influenzae or B. catarrhalis in the nasopharynx does not per se increase the risk for the development of AOM.