Table 4.

Kinetic properties of OXA-25, OXA-26, and OXA-27 β-lactamases and the enzyme from isolate A-15

SubstrateBelgium 04737 (OXA-26)Spain 327009 (OXA-25)Singapore I-16 (OXA-27)Kuwait A-15
Vmax (%)Km (μM)Vmax (%)Km (μM)Vmax (%)Km (μM)Vmax (%)Km (μM)
Cephaloridine276403359063710440
Cephalothin8903800.32603120
Cefotaxime<0.0030.2350.20.1<0.006
Cefuroxime0.0470.41051.020.340
Ceftazidime0.10.010.00050.006
Penicillin G100251001001008810065
Ampicillin5515212163264260
Piperacillin5310225541056100
Carbenicillin2521076300<0.00054295
Oxacillin5005804408403 and 0.4a 402 and 208a 600211
Imipenem2.433110.120320
Meropenem0.430.4120.04150.006
Aztreonam<0.003<0.00050.006
  • a Initial and steady state values, respectively, in a biphasic hydrolysis.