**2.4 Antimicrobial resistance (AMR) testing**

Antimicrobial susceptibility of *Salmonella* isolates from the various sources was determined using the National Antimicrobial Resistance Monitoring System (NARMS) panel according to Food and Drug Administration and National Committee for Clinical Laboratory Standards (NCCLS) recommendation (Sensititre®, Trek Diagnostics System, Inc, Westlake, Ohio). Each isolate was screened for resistance using full-range minimum inhibitory concentration. The US National Antimicrobial Resistance Monitoring System (NARMS) panels were used to compare AMR levels between domestic animal and human isolates of the same genotype in order to assess a possible role of domestic animals in transfer of AMR of *Salmonella* isolated from human cases. The antimicrobials tested included ampicillin, apramycin, ceftiofur, chlortetracycline, clindamycin, enrofloxacin, erythromycin, florfenicol , gentamicin, neomycin, oxytetracycline, penicillin, spectinomycin, sulphachloropyridazine, sulphadimethoxime, sulphathiazole, tiamulin, tilmicosin, trimethoprim/ sulphamethoxazole and tylosin. Isolates were defined as resistant according to FDA recommended breakpoints. Breakpoints were defined as minimum drug concentration above which growth of the test isolate should not occur (Logue et al. 2003).
