Carbapenemases: the Versatile β-Lactamases

SUMMARY

Carbapenemases are β-lactamases with versatile hydrolytic capacities. They have the ability to hydrolyze penicillins, cephalosporins, monobactams, and carbapenems. Bacteria producing these β-lactamases may cause serious infections in which the carbapenemase activity renders many β-lactams ineffective. Carbapenemases are members of the molecular class A, B, and D β-lactamases. Class A and D enzymes have a serine-based hydrolytic mechanism, while class B enzymes are metallo-β-lactamases that contain zinc in the active site. The class A carbapenemase group includes members of the SME, IMI, NMC, GES, and KPC families. Of these, the KPC carbapenemases are the most prevalent, found mostly on plasmids in Klebsiella pneumoniae . The class D carbapenemases consist of OXA-type β-lactamases frequently detected in Acinetobacter baumannii . The metallo-β-lactamases belong to the IMP, VIM, SPM, GIM, and SIM families and have been detected primarily in Pseudomonas aeruginosa ; however, there are increasing numbers of reports worldwide of this group of β-lactamases in the Enterobacteriaceae . This review updates the characteristics, epidemiology, and detection of the carbapenemases found in pathogenic bacteria.