Epidemiology of Streptococcus pneumoniae isolates in Gifu Prefecture

We analyzed Streptococcus pneumoniae isolates confirmed by direct PCR in Gifu prefecture between May 2002 and August 2002. We analyzed isolates of 254 strains from 6 hospitals to determine antibiotic susceptibility, genotype of penicillin-binding protein (PBP) genes and macrolide resistant genes, and the serotypes distribution of isolates from Matsubara Otorhinolaryngology Clinic. Isolates in which abnormal PBP genes of pbp1a, pbp2x, and pbp2b were identified by PCR were classified based on PCR results as follows; (i) penicillin-susceptible (PSSP) with 3 normal PBP genes, (ii) penicillin-intermediate (PISP) with an abnormal pbp2x, (iii) PISP with an abnormal php2b, (iv) PISP with abnormal pbp2x and pbp2b, (v) PISP with abnormal pbpla and pbp2x, (vi) penicillin-resistant (PRSP) with 3 abnormal PBP genes. The overall incidence of PRSP, PISP and PSSP was 121 (49%), 109 (42%) and 24 (9%), respectively, and there was a significant difference among some hospitals (p<0.05). However, there was no significant difference among the hospitals for the incidence of abnormal macrolide-resistant genes (mefA, ermB). Panipenem showed an excellent antimicrobial activity for injectable carbapenems against PRSP, following biapenem, imipenem, and meropenem. Cefditoren (CDTR) showed an excellent antimicrobial activity for oral cephalosporins against PRSP, following cefteram and cefcapene. Interestingly, there were 2 and 3 strains on MIC of CDTR for 8 and 4 microg/mL, respectively. The prevalent pneumococcal serotypes of isolates in Matsubara Clinic were 6 (17/55), following by 40 (8/55), 9 (6/5) and 15 (5/55). The endemic strains were observed in this study using pulsed field gel electrophoresis. These findings suggest the needs to continue the surveillance of bacterial resistance not only in the nationwide but also in the distict.