Antibiotic susceptibility test
Antibiotic susceptibility was determined using the SensititreTM panel (KRCDC2F; Thermo Fisher Scientific, Waltham, MA, USA) with the following antibiotics: ciprofloxacin (CIP, 0.03–0.5 µg), nalidixic acid (NAL, 2–128 µg), imipenem (IMI, 1–8 µg), colistin (COL, 2–16 µg), ampicillin (AMP, 2–64 µg), tetracycline (TET, 2–128 µg), chloramphenicol (CHL, 2–32 µg), azithromycin (AZI, 2–32 µg), gentamicin (GEN, 1–64 µg), (STR, 2–128 µg), amikacin (AMI, 4–64 µg), trimethoprim/sulfamethoxazole (SXT, 1/19–16/304), cefotaxime (FOT, 1–32 µg), ceftriaxone (AXO, 1–32 µg), cefoxitin (FOX, 4 - 32 µg), and ceftazidime (TAZ, 1–16 µg), according to Clinical and Laboratory Standards Institute guidelines (Wayne, PA, USA) . Briefly, 10 µL portions of Salmonella spp. strains (1 × 105cfu/mL) cultured overnight were thoroughly mixed with 11 mL of Muller Hinton Broth with N -Tris (hydroxymethyl) methyl-2-aminoethanesulfonic acid; 50 µL portions were placed in the wells of the SensititreTM panel. The panel was sealed with film, and the results were assessed manually after 24 h incubation at 37°C. The MIC was recorded as the lowest concentration of antibiotic that inhibit visible growth shown as turbidity or deposit of cells at the bottom of a wall. Escherichia coli ATCC25922 was used as the quality control standard.