Contribution of β-Lactamases and Porin Proteins OmpK35 and OmpK36 to Carbapenem Resistance in Clinical Isolates of KPC-2-Producing Klebsiella pneumoniae

Abstract

ABSTRACTFifty-seven carbapenem-resistantKlebsiella pneumoniaeisolates belonging to ST11 (50 isolates), ST423 (5 isolates), and two other sequence types were studied. All were positive forblaKPC-2,blaTEM-1, andblaCTX-M-14. SDS-PAGE analysis of six representative isolates demonstrated varied porin expression. Nevertheless, whenblaKPC-2was deleted, carbapenem resistance was markedly reduced. Additionally, SHV-12, DHA-1, and/or VIM-1 appeared to contribute to accessory carbapenemase activity. In contrast, OmpK35 and/or OmpK36 deficiency seemed to serve only as a minor cooperative factor.