Detection of a novel variant bla(CTX-M-3) extended spectrum beta-lactamase gene in a community-acquired Escherichia coli isolate

A highly cefotaxime- and cefepime-resistant but ceftazidime-sensitive Escherichia coli isolate was recovered from a community-acquired urinary infection of a Greek patient. Susceptibility testing, transfer assays, plasmid analysis as well as PCR and sequencing techniques were used to investigate the underlying mechanism of resistance. The isolate carried a new variant of the bla(CTX-M-3) gene that possessed a T instead of A at nt position 663. Cefotaxime resistance was transferable and carried on a 60 kb plasmid. The bla(CTX-M-3) variant was located downstream of an ISEcp1B element. The emergence of this new derivative indicates further evolution of the worldwide-distributed bla(CTX-M-3) gene.