PCR Classification of CTX-M-Type β-Lactamase Genes Identified in Clinically Isolated Gram-Negative Bacilli in Japan

Of 1,456 strains isolated from 2001 to 2003 demonstrating resistance to either oxyimino-cephalosporin, 317 strains, isolated in 57 of 132 clinical facilities, were found to harbor blaCTX-M genes by PCR. Fifty-seven, 161, and 99 strains harbored blaCTX-M genes belonging to the blaCTX-M-1, blaCTX-M-2, and blaCTX-M-9 clusters, respectively.