Probiotic Bifidobacterium Lactis Bacteria Inhibit the Invasion Phenotype of Shigella Dysenteriae Induced By Invasion Plasmid Antigen C

Shigellosis is an acute gastroenteritis and Invasion plasmid antigen C (IpaC) is the first effector protein for Shigella invasion of intestinal cells. Among lactic acid bacteria, Bifidobacterium lactis (B. lactis) has received increasing attention for protection of a potential host against gastrointestinal infections. The aim of this study was to investigate the inhibitory activity of B. lactis against Shigella dysenteriae (S. dysenteriae) harboring IpaC gene strains from clinical specimens.

Sixty stool samples of patients with bloody diarrhea were collected from three teaching hospitals in Tehran and subjected to further analysis for the identification of Shigella colonies by biochemical tests. DNA was assessed for IpaC gene by polymeraese chain reaction (PCR). Furthermore, IpaC gene expression analysis by real-time PCR was carried out to investigate whether probiotic B. lactis can inhibit the invasion phenotype of S. dysenteriae induced by IpaC.

Analysis of gene expression in S. dysenteriae harboring IpaC gene strains showed the expression of IpaC gene in treated S. dysentery with B. lactis being much lower than that of non-treated group (p<0.000). The results revealed that B. lactis at the concentration of 500 μg/ml bears strong inhibitory activity on the growth of S. dysenteriae by decreasing IpaC expression.

Our results revealed the positive role of B. lactis in reducing the expression of the ipaC gene and inhibition of epithelial cell invasion by S. dysenteriae. Therefore, probiotics can be used as a complementary biotherapeutic agent in severe Shigella infection.