Prevalence of serotypes and molecular epidemiology of Streptococcus pneumoniae strains isolated from children in Beijing, China: Identification of two novel multiply-resistant clones

Three-hundred and seventy-six strains of Streptococcus pneumoniae isolated from clinical specimens and nasopharyngeal swabs from children at daycare c enters and hospitals in Beijing China, between January 1997 and March 1998, were serotyped. Twenty-seven different serotypes were identified. The most prevalent serotypes in the carriage isolates were 6A, 19F, 23F, and 15 and were found in 66.8% of cases. Serotype data indicate that 51.8% of carrier strains would be included in the Ii-valent conjugate vaccine formulation, while inclusion of vaccine-related serotypes, increased the potential vacci ne coverage to 79.4%. Serotypes 7, 6B, 23F, 19F, 15, and 3 accounted for 62 % of clinical strains, with 70% vaccine-related serotypes. DNA fingerprinti ng of 47 penicillin resistant and 71 penicillin-susceptible/macrolide-resis tant strains by BOX polymerase chain reaction (PCR), pulsed-field gel elect rophoresis (PFGE), and penicillin binding protein (PBP)-fingerprinting iden tified two novel clones: one a serotype 23F multiresistant clone resistant to penicillin, tetracycline, erythromycin, clindamycin, and variably resist ant to chloramphenicol and trimethoprim-sulphamethoxazole; and the second a multiresistant penicillin-susceptible, macrolide-resistant serotype 6A clo ne, highly resistant also to tetracycline, clindamycin, and trimethoprim-su lphamethoxazole. The macrolide resistance determinant in 89% of erythromyci n-resistant strains tested (penicillin-susceptible and penicillin-resistant ) was the erm gene, both the erm and mef genes were simultaneously found in 6%, and mef alone in 3.4%. The data demonstrates that macrolide resistant strains in China include clonal strains and strains,vith dual mef and erm r esistance determinants.