Prevalence and antimicrobial susceptibility of Salmonella spp. in sheep fecal and hide samples before and after transportation
Two hundred feedlot hair sheep (100/trial) were surveyed to determine the incidence of Salmonella spp. in fecal and hide samples before transportation and the incidence in hide samples after transportation. Microbroth dilution plates were used to establish antibiotic resistant profiles on the samples. Twenty-seven percent of all samples (n=600) tested positive for Salmonella using several selective and enrichment media. Of those, 40% were classified as serogroup B and 48% were from serogroup C. Other serogroup values were 10% or less of the total. Thirteen percent of 158 isolates were susceptible to all antimicrobial drugs tested, 26% were resistant to only one antimicrobial, and 38% were resistant to eight or more. The most common resistance was to Sulfisoxazole (77% of isolates). Sulfisoxazole MIC levels were the only ones impacted by an interaction between trial and sample type (P=0.02).Ten antimicrobials saw an effect due to trial (P≤ 0.05) but not type (P>0.05).