RESUMO
We determined the minimum inhibitory concentration (MIC) of various antimicrobial agents against 108 strains of Streptococcus pneumoniae and 144 strains of Haemophilus influenzae isolated from respiratory organs in the First Department of Internal Medicine, Shinshu University, and affiliated hospitals between January 2000 and February 2001. The following results were obtained. 1. Fifty-one (47.2%), 56 (51.9%), and 1 (0.9%) of 108 strains of S. pneumoniae were classified as penicillin-susceptible S. pneumoniae (PSSP), penicillin-intermediate S. pneumoniae (PISP), and penicillin-resistant S. pneumoniae (PRSP), respectively. 2. Three carbapenems had potent antimicrobial activity against PISP and PRSP. Furthermore, none of the strains were highly resistant (MIC > 2 micrograms/ml) to benzylpenicillin, ampicillin (ABPC), sulbactam/ampicillin (SBT/ABPC), cefotaxime (CTX), or cefepime (CFPM). 3. Eleven (7.6%) and 6 (4.2%) of 144 strains of H. influenzae were classified as beta-lactamase-producing ABPC-resistant strains and beta-lactamase negative ABPC-resistant H. influenzae (BLNAR), respectively. Levofloxacin, sulfamethoxazole/trimethoprim, and meropenem had potent antimicrobial activity against these resistant strains. 4. BLNAR strains were more highly resistant to CTX, CFPM, SBT/ABPC, and cefaclor than beta-lactamaseproducing strains. 5. In our surveillance study regarding clinical isolates of S. pneumoniae and H. influenzae from respiratory organs in Nagano prefecture, there were regional differences in the isolation rate and antimicrobial susceptibility. The isolation rates of resistant strains were lower than those reported in a nationwide survey.