Correlation of porin genes loss with resistance to carbapenems in Klebsiella pneumoniae / 中华临床感染病杂志

ABSTRACT

Objective To investigate the molecular mechanism of Klebsiella pneumoniae resistant to carbapenem. Methods The minimal inhibitory concentrations ( MICs) of the antimicrobial agents were determined by E-test. The 23 β-lactamase genes and 2 porin genes were amplified by polymerase chain reaction (PCR) , then the products were purified and their sequences were analyzed. Results The MICs of piperacillin, piperacillin/sulbactam, amoxicillin/clavulanic acid, cefoperazone/sulbactam, cefotaxime, cefepime and aztreonam to 5 strains of Klebsiella pneumoniae were all higher than 128 μg/mL, and those of imipenem or meropenem were higher than 32 μg/mL. All isolates carried blaTEM-1 and blaDHA-1 genes. Deletion of ompK35 and ompK36 were observed in Kp01 and Kp03, and the deletion of ompK35 was also observed in Kp02 and Kp05. Base insertion of ompK36 occurred in Kp02, Kp04 and Kp05. Compared with GenBank (GU945384) , ompK35 gene mutations of G→C at base 465 and T → C at base 466 in Kp04 lead to Gln to His substitution at position 155 and Tyr to its substitution at position 156, and it might be a new subtype. Conclusion The production of DHA-1 β-lactamase combined with the loss of OmpK36 or OmpK35 in porin genes may contribute to high-level carbapenem resistance in Klebsiella pneumoniae.