Antimicrobial susceptibility testing

Antimicrobial susceptibility tests were initially performed by disk diffusion in accordance with the Clinical Laboratory Standards Institute (2010). In addition, to determine the level of sensitivity, antibiotic mean inhibitory concentrations (MICs) were determined by the broth microdilution method using 2-fold serial dilutions, as recommended by CLSI (Clinical Laboratory Standards Institute, 2012, 2014). MIC is defined as the lowest concentration of an antimicrobial agent that inhibits visible growth. Escherichia coli (ATCC25922) was used as the standard reference strain. Experiments were performed in triplicate from two or more independent experiments.