First Isolation of a CTX-M-3-Producing Enterobacter cloacae in France

At the beginning of the 1990s, a new class A extended-spectrum β-lactamase (ESBL), MEN-1 (CTX-M-1), was characterized inEscherichia coli strains isolated from Italian and German patients (1, 2). CTX-M-1 was the first member of the CTX-M β-lactamase family, which now comprises nine members: CTX-M-1 (MEN-1) (1, 2), CTX-M-2 (2), Toho-1 (7), CTX-M-3 (6), CTX-M-4 (6), CTX-M-5 (4), Toho-2 (8), CTX-M-6 (5), CTX-M-7 (5), and CTX-M-8 (3). These ESBLs conferred higher cefotaxime MICs than those of ceftazidime.