Expression of SHV-2 β-lactamase and of reduced amounts of OmpK36 porin in Klebsiella pneumoniae results in increased resistance to cephalosporins and carbapenems

A Klebsiella pneumoniae clinical isolate was resistant to cefoxitin, cefotaxime, ceftazidime, ceftazidime-clavulanate, piperacillin-tazobactam (MICs, >256 mug/ml in all cases), and meropenem (MIC, 16 mug/ml) and was intermediate to imipenem (MIC, 8 mug/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.