Effect of dietary supplement administration on excretion and antibiotic resistance of Salmonella strains in piglets

Résumé fourni par la source

Antibiotic overuse in livestock drives resistance in foodborne pathogens. This study evaluated the effect of an algae-based dietary supplement on Salmonella excretion in weaned piglets. Three groups of two piglets each (control, treated with tetracycline, and treated with Algo-Bio®) were raised. Microbiological analysis of feces over a 10-day period according to the AFNOR NF U 47-100 standard, was followed by molecular identification, characterization of virulence factors by PCR, and serotyping of the strains. A significant increase in Salmonella excretion rates was observed in control piglet 2 from day 0 (40%) to day 10 (93.3%). Excretion rates decreased from 46.6% (day 0) to 13.3% (day 10) in tetracycline-treated piglet 1, and from 33.3% (day 0) to 0% (day 4) in algae-based dietary supplement-treated piglet 2. All presumptive strains carried the invA gene, and 65.5% of these strains harbored the spvC gene. Salmonella typhimurium, Salmonella derby, and Salmonella bovismorbificans were observed at rates of 57.5%, 21.9%, and 12.3%, respectively. Antibiotic susceptibility test results showed prevalence rates of 32% in controls and 20.1% in piglets treated with Algo-Bio®. In tetracycline-treated piglets, resistance was particularly high for tetracycline (73.3%). This study demonstrated a significant reduction in Salmonella carriage in piglets treated with algae supplement.