Expression of SHV-2 β-Lactamase and of Reduced Amounts of OmpK36 Porin in <i>Klebsiella pneumoniae</i> Results in Increased Resistance to Cephalosporins and Carbapenems

Abstract

A Klebsiella pneumoniae clinical isolate was resistant to cefoxitin, cefotaxime, ceftazidime, ceftazidime-clavulanate, piperacillin-tazobactam (MICs, >256 micro g/ml in all cases), and meropenem (MIC, 16 micro g/ml) and was intermediate to imipenem (MIC, 8 micro g/ml). Decreased expression of the OmpK36 porin and expression of an SHV-2 beta-lactamase contributed to the observed resistance to these beta-lactam-containing agents.