The kinetics of CAZ-5, a novel SHV-related plasmid-mediated beta-lactamase with enhanced hydrolytic activity against ceftazidime
Labia, R.; Thabaut, A.; Morand, A.; Tiwari, K.; Sirot, D.; Sirot, J.
Drugs under Experimental and Clinical Research 15(11-12): 535-540
1989
ISSN/ISBN: 0378-6501 PMID: 2700319 Document Number: 339504
The kinetic constants for "CAZ-5", a novel plasmid-mediated beta-lactamase with noticeable activity against third-generation cephalosporins and particularly ceftazidime have been determined. Two closely-related plasmid-mediated beta-lactamases have also been studied: SHV-2 and PIT-2 (also known as SHV-1). These enzymes were synthesized constitutively; they were highly sensitive to the action of the inhibitors clavulanic acid and sulbactam and they lacked activity against the cephamycins and imipenem. PIT-2/SHV-1 had poor hydrolytic activity against the third-generation cephalosporins, SHV-2 was markedly active against cefotaxime and related compounds, whereas the new enzyme, which was also active against these cephalosporins, had a noticeably greater activity against ceftazidime. Aztreonam was slowly hydrolysed by CAZ-5 beta-lactamase, but demonstrated an unusually high affinity for this enzyme.