Three clinical strains (Escherichia coli Rio-6, E. coli Rio-7, and Enterobacter cloacae Rio-9) collected in 1996 and 1999 from hospitals in Rio de Janeiro (Brazil) were resistant to broad-spectrum cephalosporins and gave a positive double-disk synergy test. Two bla CTX-M genes encoding ␤-lactamases of pl 7.9 and 8.2 were implicated in this resistance: the bla CTX-M-9 gene observed in E. coli Rio-7 and E. cloacae Rio-9 and a novel CTX-Mencoding gene, designated bla CTX

Six clinical CTX-M-producing isolates of the family Enterobacteriaceae were detected between 1999 and 2000 in different French hospitals. Two strains produced CTX-M-1 and CTX-M-3 and four strains produced CTX-M-14, a mutant Ala-231→Val of CTX-M-9. A putative transposable element, ISEcp-1, was located 43 bp upstream of all the bla CTX-M genes. Two CTX-M-14-encoding plasmids exhibited similar restriction patterns. The CTX-M-1- and CTX-M-3-encoding plasmids were related to the CTX-M-1- and CTX-M-3-encoding plasmids previously reported in 1990 in France and in 1998 in Poland, respectively.