TABLE 1.

Antimicrobial data for E. coli N08-1503 and the transformants harboring pT168a

E. coli strainDisk diameter (mm)MIC (μg/ml)
Broth microdilutionESBL EtestEtest
CefotaximebCefotaxime-CLAcCeftazidimebCeftazidime-CLAcCefpodoximebCefpodoxime-CLACefotaximebCefotaxime-CLACeftazidimebCeftazidime-CLAcCefpodoximebCefpodoxime-CLACefepimeCefepime-CLACefotaximeCefotaxime-CLAdCeftazidimeCeftazidime-CLAdCefepimeCefepime-CLAeAmoxicillin-CLAPipercillin-TZBgCefoxitin
N08-1503 (pT168)23 (pos)24 (neg)8 (pos)11 (neg)20 (neg)15≤0.25 (neg)≤0.124 (pos)2 (neg)8 (pos)0.58≤0.1250.250.094 (neg)30.75 (neg)20.094 (pos)32>25612
DH10B (pT168)26 (pos)30 (neg)8 (pos)10 (neg)20 (neg)16≤0.25 (neg)≤0.124 (pos)1 (neg)4 (neg)0.254≤0.1250.250.094 (neg)31 (neg)20.094 (pos)64>2566
DH10B29 (neg)3316 (pos)18 (neg)27 (neg)21≤0.25 (neg)≤0.12≤0.25 (neg)0.251 (neg)≤0.125≤0.25≤0.125<0.250.094 (neg)10.38 (neg)<0.25<0.25 (neg)31.58
  • a CLA, clavulanic acid; TZB, tazobactam; pos, positive; neg, negative.

  • b Data in parentheses are the interpretations for the screen for ESBL according to CLSI document M100-S19 (2).

  • c Data in parentheses are the interpretation for confirmation of ESBL according to CLSI document M100-S19 (2).

  • d Data in parentheses are the interpretation for confirmation of ESBL according to the manufacturer's instructions in document 75001448-MH0383 (Etest for detection of ESBL; AB bioMérieux, Solna, Sweden). The overall interpretation of the phenotype is non-ESBL producer as both strips were negative.

  • e Data in parentheses are the interpretation for confirmation of ESBL according to the manufacturer's instructions in document 75002213-MH0344 (Etest for detection of ESBL; AB bioMérieux, Solna, Sweden). The overall interpretation of the phenotype is ESBL producer as one strip was positive.