Serotype distribution and antimicrobial susceptibility profiles of group Bstreptococcus strains from pregnant women in Beijing, 1994-99

Objectives To investigate the serotype distribution among group B streptoco ccus (GBS) strains isolated in Beijing areas from 1994 to 1999 in order to determine the optimal components of future GBS vaccine; also, to assess the antimicrobial susceptibility profile of the strains. Methods A total of 155 CBS strains were isolated from 1994 to 1999. Serotyp ing was performed by double diffusion in agarose (Ouchterlony method). Susc eptibility to ampicillin, penicillin G, oxacillin, erythromycin, clindamyci n, cephazolin, cefuroxime, cefoperazone, gentamicin and amikacin was assess ed by disc diffusion. Results Seven serotypes were identified. Type II (II/C; 36%), type III (III /R; 26%), type la (la/c; 18%) were the most common. All strains were suscep tible or moderately susceptible to ampicillin, penicillin G, oxacillin, cep hazolin, cefuroxime and cefoperazone. A dramatic increase in erythromycin a nd clindamycin resistance occurred when comparing the period 1994-97 and 19 98-99. For serotype III/R, the proportion resistant to macrolides was 22.5% . Conclusion GBS serotypes la, II and III may be important components of a fu ture multivalent GBS vaccine for use in Beijing areas. The susceptibility o f the GBS strains to penicillin G and ampicillin supports continued use of either of these antibiotics for prevention of early-onset GBS disease. The use of erythromycin as a second-line agent can be questioned with regard to the increased bacterial resistance. Continuous surveillance for changes in susceptibility is of considerable clinical importance.