Antibiotic resistance and substrate profiles of the class A carbapenemase KPC-6.

The class A carbapenemase KPC-6 produces resistance to a broad range of β-lactam antibiotics. This enzyme hydrolyzes penicillins, the monobactam aztreonam, and carbapenems with similar catalytic efficiencies, ranging from 10(5) to 10(6) M(-1) s(-1). The catalytic efficiencies of KPC-6 against cephems vary to a greater extent, ranging from 10(3) M(-1) s(-1) for the cephamycin cefoxitin and the extended-spectrum cephalosporin ceftazidime to 10(5) to 10(6) M(-1) s(-1) for the narrow-spectrum and some of the extended-spectrum cephalosporins.