This work further confirmed the predominant role of ISEcp1 in the mobilization of bla(CTX-M) genes of the CTX-M-1 cluster and the presence of In35, of an integron similar to In60 and a novel complex Class 1 integron.

No abstract

Kluyvera ascorbata produces a ␤-lactamase that results in an atypical susceptibility pattern, including lowlevel resistance to penicillins, cephalothin, and cefuroxime, but this resistance is reversed by clavulanate. Ten nucleotide sequences of the corresponding gene, bla KLUA , were obtained and were found to have minor variations (96 to 100%). Otherwise, bla KLUA was found to be similar (95 to 100%) to some plasmid-encoded CTX-M-type ␤-lactamases. Finally, mobilization of bla KLUA on a plasmid was found to be mediated probably by a genetic mobile element like ISEcp1.

Resistance genes borne by the narrow host-range IncF replicon spread readily as this replicon is well adapted to E. coli. This is observed for blaTEM-1 and blaCTX-M-15 and, to a lesser extent, for blaCTX-M-14. Transposition immunity seems to play an important role in the diffusion process.