Nucleotide sequence of a plasmid-mediated cephalosporinase gene (blaLAT-1) found in Klebsiella pneumoniae

The nucleotide sequence of the gene encoding a novel cephalosporinase (LAT-1), carried by a non-self-transferable plasmid from Kiebsiella pneumoniae, has been determined. It was found that the sequence shares a high degree of homology with the Citrobacterfreundii OS60 ampC structural gene. Possession of plasmid-mediated extended-spectrum deriva-tives of TEM-1/2 or SHV-1,B-lactamases is the main cause of resistance of Kiebsiella pneumoniae to broad-spectrum cepha-losporins (9). These enzymes are ineffective against cephamy-cins and subject to strong inhibition by clavulanate and sulbac-tam. However, there have been studies describing novel plasmid-mediated,B-lactamases which resemble the chromo-somal cephalosporinases in that they confer resistance to virtually all cephalosporins, including cephamycins, and are not inhibited by the P-lactamase "suicide " inhibitors (1-4, 7, 8, 14). In a previous study, we reported the identification of such a P-lactamase, designated LAT-1 (14). The enzyme was en