Etest mic test strip

The human colon adenocarcinoma HT-29 cell line was purchased from the Korea Cell Line Bank. To analyze bacterial adhesion, HT-29 cells were cultured in Roswell Park Memorial Institute-1640 medium (Sigma–Aldrich, USA) supplemented with 10% (vol/vol) heat-inactivated fetal bovine serum (Gibco, USA), 0.1 U/L of penicillin, and 100 mg/L of streptomycin maintained at 37 °C in an atmosphere of 5% CO₂/95% air. An antibiotic-free medium containing bacteria was added to HT-29 cells, which were then incubated at 37 °C for 120 min. After incubation, nonadherent bacteria were removed by washing with phosphate-buffered saline, and adhered bacteria were counted after detachment using 0.05% trypsin–EDTA. The adhesion rate was calculated as the relative ratio of the adhered bacterial colony-forming unit (CFU) to the initial inoculated bacterial CFU.
Antibiotic resistance was expressed by determining the minimum inhibitory concentrations for the eight antibiotics listed by the European Food Safety Authority (EFSA)— chloramphenicol, clindamycin, erythromycin, gentamicin, kanamycin, streptomycin, tetracycline, and vancomycin—using the E-test–MIC Test Strip (Liofilchem, Italy) (EFSA, 2012 ).