MOLECULAR-CLONING AND NUCLEOTIDE-SEQUENCE OF A NEW PLASMID-CODED KLEBSIELLA-PNEUMONIAE BETA-LACTAMASE GENE (SHV-2A) RESPONSIBLE FOR HIGH-LEVEL CEFOTAXIME RESISTANCE

Patient specimen isolates of Klebsiella pneumoniae exhibiting an MIC of > 128 mg/l for cefotaxime were shown to produce a beta-lactamase with a pI of 7.6, which is encoded on a 66 kb conjugative plasmid. A 3.5 kb Bam H I fragment of this plasmid was cloned into pLG339 and totally sequenced. The nucleotide sequence of the beta-lactamase gene presented 99% homology to those of SHV-2 and SHV-3, the deduced amino acid sequence differed from both enzymes in one and two positions, respectively, leading to the denomination SHV-2a for the new enzyme. Since the kinetic data of SHV-2a and SHV-2 are similar, too, quantitative effects mediated by distinctly different promotor regions are thought to be responsible for the elevated MIC for cefotaxime induced by SHV-2a.