Table 2.

Animal and human E. coli isolates from Iowa expressing an AmpC phenotypea

IsolatebCoresistance (%)cIEF results (%) ford:
ChloramphenicolTetracyclineSulfisoxazoleStreptomycinGentamicinTobramycinCiprofloxacinpI 5.4pI ∼8.9CMY-2e
Animal (n = 59)54 (91.5)59 (100)59 (100)58 (98.3)41 (69.5)37 (62.7)9 (15.2)20 (33.9)59 (100)55 (94.8)
Human (n = 6)4 (66.7)4 (66.7)4 (66.7)4 (66.7)3 (50)2 (33.3)2 (33.3)2 (33.3)6 (100)2 (33.3)
  • a Ceftriaxone, ceftazidime, and aztreonam MICs were ≥8 μg/ml, the cefoxitin MIC was ≥8 μg/ml, and the cefepime MIC was ≤4 μg/ml.

  • b Fifty nine (15.6%) of the 377 animal isolates tested expressed the AmpC phenotype. Of those, 42 (22.2%) were bovine isolates (n = 189) and 17 (9.0%) were porcine isolates (n = 188) . Six (0.6%) of the 1,017 human isolates tested expressed the AmpC phenotype.

  • c Coresistances associated with the organisms expressing an AmpC phenotype.

  • d Percentage of isolates with an AmpC phenotype with a band that migrates at pI 5.4 or pI ∼8.9 on isoelectric focus (IEF) analysis.

  • e Percentage of isolates with an AmpC phenotype that amplify a CMY-2-like gene using PCR.