bla CTX-M Genes in Escherichia coli Strains from Croatian Hospitals Are Located in New ( bla CTX-M-3a ) and Widely Spread ( bla CTX-M-3a and bla CTX-M-15 ) Genetic Structures

CTX-M-producing Escherichia coli isolates from three Croatian hospitals were analyzed. All bla CTX-M-15 genes and one bla CTX-M-3a gene resided in widely spread IS Ecp1 transposition modules, but other bla CTX-M-3a genes were in a new configuration with two IS 26 copies, indicating a new event of gene mobilization from a Kluyvera ascorbata genome. The study confirmed the role of the E. coli ST131 clonal group with IncFII-type plasmids in the spread of bla CTX-M-15 and of IncL/M pCTX-M3-type plasmids in the dissemination of bla CTX-M-3a .