Characteristics of Escherichia coli Isolated from Bovine Mastitis Exposed to Subminimum Inhibitory Concentrations of Cefalotin or Ceftazidime

Figure 3

Extended spectrum beta-lactamase (ESBL) production of isolates recovered after induction by cefalotin (a) or ceftazidime (b). Isolates at various generations are listed on the X-axis. Differences were calculated as diameter of the inhibition zone of ceftazidime plus clavulanic acid subtracted from their respective single discs. An isolate was designated an ESBL producer if the difference was > 5 mm.

(a)

(b)