Table 4.

Representative strains with low MICs of ESBL screening agents: standard- and high-inoculum MICs

Strain (enzyme)MIC (μg/ml) of drug at the indicated inoculum (CFU/ml)a
MEMCTTCTXCAZCROFEPATMTZP
105107105107105107105107105107105107105107105107
P. mirabilis 177 (TEM-10)0.060.060.250.250.12142560.542640.253228
E. coli MISC 377 (SHV-10)≤0.015≤0.0150.12≤0.03≤0.06≤0.06≤0.254≤0.06≤0.060.120.250.12≤0.0648
K. pneumoniae 98 (TEM-10, TEM-1, SHV-1)0.0340.2511128512>1,02441284>128256>1,0241,024>1,024
K. pneumoniae 221 (TEM-12-like)0.060.120.120.250.58128>1,02415128>1288>1,024816
K. pneumoniae 222 (SHV-3, SHV-1 or -2b)0.030.030.060.0621281845121>1280.5448
C. freundii M421b (SHV-3-like)0.030.060.121225613245120.5>1280.532216
E. cloacae 154 (SHV-3)0.060.121648>1,02445124>1,0241>1282>1,0242>1,024
M. morganii M518b (SHV-4)0.12114264212811280.0644320.564
  • a Abbreviations: MEM, meropenem; CTT, cefoteten; CTX, cefotaxime; CAZ, ceftazidime; CRO, ceftriaxone; FEP, cefepime; ATM, aztreonam; TZP, piperacillin-tazobactam.

  • b Additional testing required to identify this enzyme.