Sequence analysis and biochemical characterisation of chromosomal CAV-1 (Aeromonas caviae), the parental cephalosporinase of plasmid-mediated AmpC ‘FOX’ cluster

Abstract
Aeromonas caviae CIP 74.32 was resistant to amoxicillin, ticarcillin and cephalothin, and susceptible to cefoxitin, cefotaxime, ceftazidime, aztreonam and imipenem. This strain produced a cephalosporinase (pI 7.2) and an oxacillinase (pI 8.5). The cephalosporinase gene cav-1 was cloned and sequenced. Unlike A. caviae donor, Escherichia coli pNCE50 transformant producing CAV-1 β-lactamase was resistant to cefoxitin. The deduced protein sequence CAV-1 contained 382 amino acids, and shared >96% homology with FOX-1 to FOX-5 cephalosporinase. CAV-1 presented only two amino acid substitutions (Thr270Ser and Arg271Ala) with FOX-1. CAV-1 is the chromosomal putative ancestor of the FOX family, a cluster of class C/group 1 plasmidic cephalosporinases spreading in Klebsiella and E. coli clinical isolates via conjugative plasmids.

This publication has 23 references indexed in Scilit: