Prevalence and Antimicrobial Susceptibility of E. coli and Salmonella spp. in Market Show Swine and Cattle

Fecal samples were collected from market hogs (n=82) and steers (n=84) at a statewide livestock show in Texas. Samples were analyzed to determine the prevalence and antimicrobial susceptibility of generic Escherichia coli and Salmonella spp. Escherichia coli populations were higher in hogs with an LSMean of 6.12 log10 CFU/g of feces compared to steer samples at 5.57 log10 CFU/g (P<0.05). Salmonella was more prevalent in hog fecal samples than steer samples (P<0.05) with 19.05% of hogs and 3.61% steers testing positive. Microbroth dilution plates were used to evaluate antimicrobial susceptibility. Market hog E. coli isolates (n=330) were resistant to Tetracycline and Sulfisoxazole with values of 96.67% and 69.70%; whereas steer isolates (n=332) were resistant to Tetracycline and Streptomycin with values of 55.12% and 32.53%, respectively. Market hog Salmonella isolates (n=18) were resistant to Tetracycline with a value of 77.78%; whereas steer isolates (n=5) were pansusceptible to all antimicrobials tested.