RESUMEN
Antimicrobial susceptibility and beta-lactamase producibility were tested in 848 clinical strains collected at 8 hospitals in Kanagawa prefecture during the period from December 1999 to February 2000. Positive rates of beta-lactamase used the nitrocefin method (Cefinase) were 21.9% of Staphylococcus aureus, 10.0% of Haemophilus influenzae, and 99.0% of Moraxella catarrhalis. Furthermore, on the acidometric method (P/Case test) penicillinase (PCase), cephalosporinase (CEPase), and both of PCase and CEPase were found to be positive in 19.0%, 16.0%, and 16.0% for Escherichia coli, 6.2/0/3.1% for Klebsiella pneumoniae, 0/66.3/26.5% for Enterobacter cloacae, 2.8/57.7/15.5% for Serratia marcescens, and 4.0/15.0/22.0% for Pseudomonas aeruginosa, respectively. Based on the assessment of minimal inhibitory concentrations (MICs) of antibacterial agents among beta-lactamase producing strains, there were 5 strains (4 strains of K. pneumoniae and 1 strain of E. coli) that may be ESBLs producing bacteria out of a total of 466 strains of Enterobacteriaceae and P. aeruginosa. During this process, 1 strain of class-B beta-lactamase-producing E. cloacae was isolated. MRSA were found in 79.2% of S. aureus, and BLNAR were found in 8.9% of H. influenzae.