Abstract
Simple Summary Salmonellais an important foodborne pathogen that represents a very critical threat to poultry industry worldwide. This study concerns an important aspect of human food and health problem by treating a common zoonotic bacterial disease in poultry industry. Owing to the increased resistance to antibiotics amongSalmonellaentericaserotypes, we aimed to explore the beneficial effects of different probiotics strains as alternative sources of protection against infection in broiler chickens. Three probiotic strainsLactobacillus(Lacticaseibacillus)caseiATTC334,Bifidobacterium breveJCM1192 andBifidobacterium infantisBL2416) improved body weight gain and prevented the deleterious effects and mortality induced bySalmonellainfection in chicks through different mechanisms, including competitive exclusion and the promotion of cytokines' release. ChickenSalmonella entericaserovars are enteric bacteria associated with massive public health risks and economic losses. There is a widespread antimicrobial resistance amongS.entericaserotypes, and innovative solutions to antibiotic resistance are needed. We aimed to use probiotics to reduce antibiotic resistance and identify the major probiotic players that modify the early interactions betweenS.entericaand host cells. One-day-old cobb broiler chicks were challenged withS. typhimuriumafter oral inoculation with different probiotic strains for 3 days. The adherence of different probiotic strains to Caco-2 intestinal epithelial cells was studied in vitro.Lactobacillus(Lacticaseibacillus)caseiATTC334 andBifidobacterium breveJCM1192 strains attached to Caco-2 cells stronger thanB. infantisBL2416.L. caseiATTC334 andB. breveJCM1192 reducedS. typhimuriumrecovery from the cecal tonsils by competitive exclusion mechanism. AlthoughB. infantisBL2416 bound poorly to Caco-2 epithelial cells, it reducedS. typhimuriumrecovery and increased IFN-gamma and TNF-alpha production.L. caseiATTC334,B. breveJCM1192 andB. infantisBL2416 improved body weight gain and the food conversion rate inS. typhimurium-infected broilers.B. longumNcc2785 neither attached to epithelial cells nor induced IFN-gamma and TNF-alpha release and consequently did not preventS. typhimuriumcolonization in broiler chickens. In conclusion, probiotics prevented the intestinal colonization ofS. typhimuriumin infected chickens by competitive exclusion or cytokine production mechanisms.