Antimicrobial susceptibilities and serotypes of Streptococcus pneumoniae in southwestern Japan and correlation of penicillin-binding protein 2b and 2x mutations in susceptibilities of penicillin G and cefotaxime

MICs of penicillin G and other drugs and serotypes were determined for 218 strains of Streptococcus pneumoniae isolated from children in southwestern Japan. Twenty-one (9.6%) and 81 (37.2%) isolates were penicillin-resistant (MIC greater than or equal to 2.0 mu g/ml) and intermediate (MIC 0.13-1.0 m u g/ml), respectively. Panipenem was most active parenteral agent against p enicillin-intermediate (MIC90 0.125 mu g/ml) and -resistant strains (MIC90 0.25 mu g/ml). Among oral beta-lactam agents, cefditoren had good activity against penicillin-intermediate and resistant strains (MIC90 0.5/1.0 mu g/m l). Serogroup 6 was the most prevalent (65/218) among all strains and 19F ( 44 strains) was the most prevalent among penicillin-intermediate and -resis tant strains. Both pbp2b resistant and susceptible genes were found in peni cillin-intermediate strains. Pbp2x resistant genes were found in 33 of 80 ( 41.3%) cefotaxime-susceptible strains. These results suggest that possible resistance mechanisms may occur even in drug susceptible strains and that d rug susceptibility survey should be updated carefully in Japan. (C) 2000 El sevier Science Inc. All rights reserved.