Antibiotic susceptibility and serotype distribution of Streptococcus pneumoniae. Stable incidence of antibiotic-resistant isolates and common serotypes.

The serotype distribution and antibiotic susceptibility of 200 pneumococci isolated from clinical specimens in 1981 were determined. These results were compared with the susceptibility of organisms determined in 1974 and the serotype distribution of organisms determined in 1974 and 1977. Penicillin G, tetracycline, erythromycin, and chloramphenicol were tested in both 1974 and 1981. No isolates resistant to penicillin, erythromycin, or chloramphenicol were found, and the percent of isolates resistant to tetracycline and of moderate susceptibility to penicillin were similar in the 2 yr. An increasing incidence of pneumococci with decreased susceptibility to these antibiotics was not observed. Vancomycin was tested in 1981 only and no resistant isolates were identified. The distribution of serotypes during each time period was also similar. Our results establish a stable, low-level incidence of antibiotic-resistant pneumococci at our hospital, as well as a stable distribution of serotypes.