Control of Escherichia coli O157:H7 by using Lactobacillus reuteri in environmental matrices

Abstract

Shiga toxin-producing Escherichia coli (STEC) are recognized as causing foodborne diseases. Serotype O157:H7 is the most associated with sporadic cases and outbreaks of diarrhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS), being Argentina the country whit the largest registry of cases in children under 5 years old. The transmission to man is produced by the consumption of undercooked meat, vegetables, water contaminated by cattle feces, person-to-person contact, and the environment. Cattle are the main reservoir, shedding these pathogens in their feces contaminating in this way the environment. Some studies demonstrated that STEC survive for long periods in drinking troughs, soil and feces. Species of Lactobacillus present beneficial effects for animal and human health. One of them is the antibacterial activity. The antagonism allows strains such as Lactobacillus reuteri (L. reuteri), to become a useful biotechnological tool to control O157:H7 in various matrices, including cattle environment. This study aims to determine the viability of O157:H7 and the inhibitory activity of L. reuteri in manure, water and soil.Strains of E. coli O157:H7 isolated from beef cattle and L. reuteri isolated from pigs were used. The inoculation was performed in parallel in soil, manure and water. The containers were covered and maintained at room temperature. Ten samples were taken over 2 months. The viability study of the O157:H7 and L. reuteri strains were carried out by counting colony forming unit (CFU).During the first 2 days of sampling, there were few CFU counts both of O157:H7 and L. reuteri, then the counts increased up to day 30, and finally a total reduction of O157:H7 was achieved in the three matrices. It has been shown that the rural population exposed to direct contact with feces of cattle has a higher incidence of HUS than the urban population. The results of this study could be useful for the biological control of O157:H7 by a probiotic potentially strain of L. reuteri at farm level, reducing the exposure of people to the pathogen.