Ceftazidime

Broth-microdilution assays were performed to determine the antibiotic susceptibility and minimum inhibitory concentrations (MICs) for 9 β-lactam antibiotics and garlic oil (≥99%, Shanghai Macklin Biochemical Co., Ltd., Shanghai, China, Figure S1), including cefoxitin, ceftriaxone, ceftazidime, ceftriaxone, cefixime, cefquinome, meropenem, amoxicillin, and ampicillin (Shanghai Macklin Biochemical Co., Ltd., China) as recommended by the Clinical and Laboratory Standards Institute (CLSI 2023) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST 2020) [55 ,56 ]. The above antibiotics are commonly used in veterinary clinical treatment of E. coli infection. Susceptibility to cefquinome was determined in reference to previous research [57 (link)]. All drugs were diluted 2-fold in MHB and mixed with an equal volume of bacterial suspension in a 96-well microtiter plate. Each test was repeated 3 times. Escherichia coli ATCC^® 25922™ was used as the quality-control strain.

Broth-microdilution assays were performed to determine the antibiotic susceptibility and minimum inhibitory concentrations (MICs) for 10 antibiotics, including ceftiofur, cefquinome, ceftazidime, ceftriaxone, meropenem, norfloxacin, ciprofloxacin, gentamycin, kanamycin and amikacin (Shanghai Macklin Biochemical Co., Ltd, China) as recommended by the Clinical and Laboratory Standards Institute and the European Committee on Antimicrobial Susceptibility Testing. The above antibiotics are commonly used in veterinary clinical treatment of E. coli infection. Susceptibility to ceftiofur and cefquinome was determined in reference to previous research (23 (link)). All drugs were diluted 2-fold in MHB and mixed with an equal volume of bacterial suspension in a 96-well microtiter plate. Each test was repeated three times. Escherichia coli ATCC^® 25922™ was used as the quality-control strain (without magnolol). According to a previous report, bacteria resistant to ≥3 different classes of antibiotics were considered MDR (24 (link)).