Molecular Studies on the prophylactic effect of probiotics on Salmonella typhimurium infected chicks

Abdelhafez SM, Abdelwahab AMO, Azza Salah Eldemerdash and Ammar AA

Abstract

The ability of probiotics to protect chicks against S.typhimurium was evaluated. Challenge experiment was designed using 120 one day old chicks divided into 4 groups. The challenging S. typhimurium was counted in liver and cecum samples and the results shows that counts of the probiotics pre-treated group were significantly reduced when compared to those of positive control group. The phagocytic percent of chicks of positive control group were 38.40%, 26% and 18% while that of pre-treated group were 54.20%, 38.10% and 36.40% in 7, 14 and 21 days old respectively. Phagocytic indexes (PI) of positive control group were 1.0±0.10, 1.0±0.20 and 1.0±0.0 while those of pre-treated group were 1.50±0.20, 1.10±0.08 and 1.10±0.04in 7, 14, and 21 days old respectively. S. typhimurium from ceacal digesta were used for extraction of total RNA to assess the expression of 4 virulence genes (hilA, hilC, hilD and sipC) using Real Time PCR. The obtained data revealed that CT means of hilA, hilC, hilD and sipC of control group and pre-treated group were as follow 20.31 and 17.68, 17.43 and 16.85, 17.03 and 16.72 and 18.78 and 17.98 respectively. It was concluded that probiotics has an impact on S. typhimurium and caused an imbalanced virulence gene expression.

Key words

probiotics, S. typhimurium, chicks