Three-Year Trend in Antimicrobial Resistance and Genotypes among Salmonella in Swine and Humans

The aim of this study was to determine antimicrobial resistance among Salmonella isolated from swine and humans in North Carolina, compare genotypes among isolates from humans originated from pig-producing areas and characterize important genes. Resistance to 9 and 11 of the 12 antimicrobial agents tested was detected among isolates from swine and humans respectively. Frequency of resistance to tetracycline and b-lactams was significantly higher among isolates from swine than humans (p <0.05). Two common multi-drug resistance (MDR) patterns were found among isolates from apparently healthy swine: AmKmStSuTe and AmCmStSuTe. However, the former MDR pattern was rare among clinical isolates. Genotyping revealed that two predominant genotypes, one composed of clinical isolates and the other non-clinical were noticed. Further characterization using Salmonella plasmid virulence; spvA gene also revealed that this gene is absent among the most common MDR pattern, AmKmStSuTe, in swine.