TABLE 3.

Kinetic parameters for purified β-lactamase OXA-48 from K. pneumoniae 11978 compared to those for OXA-40 from A. baumannii CLA-1a

SubstrateOXA-48OXA-40b
kcat (s−1)Km (μM)kcat/Km (mM−1 · s−1)kcat (s−1)Km (μM)kcat/Km (mM−1 · s−1)
Benzylpenicillin245406,100523220
Ampicillin3405,20065522020
Ticarcillin455582016020
Piperacillin7541018012350
Cephalothin32015037250
Cephaloridine2277551,0005
Cefotaxime1019060NDcd
Ceftazidime45,1001202,50010
Cefepime11606ND
Cefpirome839020ND
Oxacillin253085028763
AztreonamNDND
Imipenem2141450.16.515
Meropenem0.12000.5ND
  • a Data are means of three independent experiments. Standard deviations were within 10% of the means.

  • b Data are from reference 12.

  • c ND, no detectable hydrolysis (<0.01 s−1).

  • d —, not determinable.