CLONING AND EXPRESSION IN ENTEROBACTERIACEAE OF THE EXTENDED-SPECTRUMBETA-LACTAMASE GENE FROM A PSEUDOMONAS-AERUGINOSA PLASMID

An extended-spectrum beta-lactamase, the gene for which is located on plasmid pMS350 in Pseudomonas aeruginosa strains, hydrolyzes carbapene ms and other extended-spectrum beta-lactam antibiotics. We cloned the pMS350 beta-lactamase gene in an Escherichia coli K-12 strain using th e vector plasmid pHSG398, and subcloned it into pMS360, a plasmid with a wide host-range. This resulted in the formation of the recombinant plasmid, pMS363, containing a 4.1-kb DNA insert that includes the exte nded-spectrum beta-lactamase gene. Plasmid pMS363 was introduced into the P. aeruginosa PAO strain or into six species of Enterobacteriaceae , and the specific activities of the beta-lactamase and MICs of variou s beta-lactam antibiotics were estimated. The cloned gene was capable of expression in these strains and caused resistance to carbapenem, pe nem and other beta-lactam antibiotics, with the exception of aztreonam .