Abstract
Extended-spectrum β-lactamase producing Enterobacteriaceae other than Escherichia coli and Klebsiella spp., especially AmpC β-lactamase producing organisms, were examined from January to June 2000; 903 isolates were isolated from 6 hospitals in Kinki, Japan. Of these, 88 isolates (9.7%) which MICs of cefotaxime (CTX) and/or ceftazidime (CAZ) were 16≥μg/mL, were tested by the modified double-disk synergy test (mDDST) using cepepime (CFPM), CTX, and CAZ disks. We found that 10 (1.1%) of 88 isolates were positive by mDDST, and CFPM-disk was more detectable disk than the other 2 disks.The percentage of mDDST positive isolates in 6 hospitals was 0 to 2.9%. ESBL gene types were MEN-1-derived (Enterobacter cloacae (4), Citrobacter freundii (3), Serratia marcescens (1)) and Toho-1 derived (C. freundii (1), Proteus mirabilis (1)). ESBL-producing isolates from the same hospital were differently cloned using random amplification of polymorphic DNA (RAPD) analysis, enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR), and phenotypical analysis (serotype, antibiogram and biotype).
