2017 ACVIM Forum Research Abstract Program

Data collected during the first 5 years of this program showed that the modes and MIC 50 values remained stable (within one doubling dilution) for each antimicrobial tested against E. coli from both dogs and cats for each year of testing; MIC 90 values were stable over the years tested with some exceptions. For amoxicillin/ clavulanic acid and ampicillin, mode and MIC 50 values remained the same (4 lg/mL) and MIC 90 values ranged from8-> 16 lg/mL. During this time, the in vitro testing for cefovecin, cefpodoxime, and ceftiofur were steady, the mode, MIC 50 , and MIC 90 values ranged from 0.5 to 2 lg/mL, with a few single drug, single year MIC 90 values testing outside that range. The mode and MIC 50 values for the fluoroquinolones (enrofloxacin, marbofloxacin and orbifloxacin) all tested at ≤0.12 lg/mL, while MIC 90 values ranged from 0.06 to 4 lg/mL. For trimethoprim/sulfamethoxazole, mode and MIC 50 values were stable (≤0.12 lg/mL) and MIC 90 values ranged from ≤0.25 to 1 lg/mL. In vitro testing of cephalexin was included in 2015. The mode and MIC 50 values for this single year of testing E. coli from both dogs and cats were both 8 lg/mL, while the MIC 90 value was 16 lg/mL in cats and >64 lg/mL in dogs. Screening and phenotypic confirmation only of Extended-Spectrum b-Lactamase (ESBL) production in E. coli were done following CLSI standards. Over the 5 years of testing, 1.2% (23 of 1933) of the E. coli isolated from dogs and 0.8% (11 of 1367) of the E. coli isolated from cats were confirmed as ESBL-producing strains.