Kinetics Study of KPC-3, a Plasmid-Encoded Class A Carbapenem-Hydrolyzing β-Lactamase

Abstract

The kinetic activity of KPC-3, a plasmid-encoded class A carbapenemase, was studied. It hydrolyzed penicillins, cephalosporins, carbapenems, and even sulbactam. The best substrate was cephalothin (k cat/K m ‫؍‬ 3.48 M ؊1 s ؊1 ). The efficiency of the enzyme was similar for imipenem and meropenem (k cat /K m , 1.4 and 1.94 M ؊1 s ؊1 , respectively).

bla KPC RNA Expression Correlates with Two Transcriptional Start Sites but Not Always with Gene Copy Number in Four Genera of Gram-Negative Pathogens

“…Little is known about the role gene expression plays in KPC-mediated resistance or how the level of expression may affect susceptibility testing. Hydrolysis of carbapenems by KPCs has been demonstrated in vitro (1,21,22); however, multiple studies have reported variability in susceptibility testing of KPC-producing clinical isolates (2,3,13,22). Although variation in KPC enzyme production could contribute to the variability seen during susceptibility testing, it is difficult to assess the influence of the KPC ␤-lactamase on susceptibility testing using clinical isolates which may harbor multiple ␤-lactamases and may have alterations in outer membrane proteins (4,7,9,10,21,24).…”

The KPC type beta-lactamases: new enzymes that confer resistance to carbapenems in Gram-negative bacilli.

“…The catalytic activity with ceftazidime is approximately 30 times higher than the KPC-1/2 enzyme [44].…”

“…Other variants (KPC-3 to KPC-5) differing from KPC-1/2 only two amino acid substitutions [39,[43][44]50]. DNA sequence analysis of the KPC-5 enzyme gene showed that was 99% identical to both bla KPC-2 and bla KPC-4 genes, with only single-nucleotide differences from either β-lactamase gene.…”

Detection of Carbapenem-Resistant Klebsiella Pneumoniae Isolates from Clinical Specimens in Nnamdi Azikiwe University Teaching Hospital, Nnewi

“…Carbapenemases are sub-class of β-lactamase enzymes that are classified by their specific resistant mechanisms, (such as AmpC and others), this research will concentrate on Klebsiella pneumoniae carbapenemase (KPC). The KPC enzyme confers resistance to all β-lactam agents including penicillins, cephalosporins, monobactams, and carbapenems (Smith et al, 2003;Alba et al, 2005).…”