Microbiology of acute otitis media with particular reference to the feasibility of pneumococcal immunization.

Middle-ear fluid was aspirated in 103 episodes of acute otitis media occurring in 100 South Australian children aged from four months to 14 years in 1977, and in 1978. Bacteria were cultured from the middle-ear fluid in 66% of cases, and viruses were grown in three cases in conjunction with bacteria. The bacteria grown were pneumococci in 30 cases (29%), Haemophilus influenzae in 26 cases (25%), beta-haemolytic streptococci in 12 cases (12%) and Neisseria spp. in six cases (6%). Pneumococci and H. influenzae were cultured from children of all ages, whereas beta-haemolytic streptococci were more frequently isolated in children aged five years and older. Countercurrent immunoelectrophoresis yielded positive results in 35% of culture-positive pneumococcal infections and gave additionally the positive reaction for pneumococci in two cases where culture produced negative results. The pneumococci which were isolated belonged to 12 serotypes; 26 of the 30 isolates were serotypes for which pneumococcal vaccines are currently available. There were appreciable differences in the distribution of serotypes from that encountered in a study of nasal carriage amongst healthy schoolchildren living in the same district.