Abstract

Sport animals and livestock farms are sources of pathogens, including Salmonella spp. that were resistant to antimicrobial agents and carries antibiotic resistance genes. This study aimed to isolate Salmonella spp. from sports animals and livestock farms in Southern Thailand, and to characterize the antimicrobial resistance profile of the isolates. A total of 241 samples were collected from sport animals (fighting cocks, fighting bulls, and riding horses) and swine breeding farms. The suspected Salmonella colonies were identified using Matrix-Assisted Laser Desorption/ Ionization Time-Of-Flight (MALDI-TOF) MS. Antimicrobial susceptibility against the isolates and detection of the antibiotic resistance genes were investigated. It was found that 20.3% (49/241) of the animal specimens were positive for Salmonella spp. The swine samples showed the highest prevalence of Salmonella spp., with a prevalence of 31.5% and 62.6% in feces and soil of the farms, respectively. A total of 98 Salmonella spp. isolates were isolated and tested for their antimicrobial susceptibility. Tetracycline resistance was the most common (48.1%), followed by ampicillin (40.4%). The minimum inhibitory concentration (MIC) of tetracycline ranged from ≤1 to ≥16 µg/mL across all Salmonella isolates. Highly resistant strains exhibited MIC90 values of ≥16 µg/mL, indicating that 90% of the isolates were inhibited at this concentration. Among the tetracycline resistance genes, tetA and tetG genes were the most prevalent, detected in 85.0% of the samples, followed by tetB (47.5%). For species identification, 7 isolates that showed multi-drug resistance (MDR) were closely similar to S. enterica as detected by invA gene sequencing. These findings contribute to understanding and controlling the spread of antibiotic resistance genes in Salmonella spp. from animals.