Combined disk test
Apply one tablet of:
A = Cefotaxime (CEFOTAXIME)
B = Cefotaxime+Clavulanate (CEFOTAXIME+CLAVULANATE)
C = Cefotaxime+Cloxacillin (CEFOTAXIME+CLOXACILLIN)
D = Cefotaxime+Clavulanate+Cloxacillin (CEFOTAXIME+CLAVULANATE+CLOXACILLIN)
on an inoculated Mueller Hinton agar plate (McFarland 0.5).
Interpretation
Neither ESβL nor AmpC: All zones within 2 mm of each other. CTXCC = Cefotaxime + Clavulanate + Cloxacillin Note : “-“ means that the difference is irrelevant for the mechanism (i.e. the difference between CTXCC compared to CTX30 is irrelevant for the detection of ESBL).
In strains possessing both chromosomal (Enterobacter, Cit. freundii etc.) or plasmidic AmpC beta lactamases and ESBLs, Boronic acid or Cloxacillin, are used as inhibitors of the AmpC betalactamase.