**4. Infection source and colonization management**

*E. coli* O157:H7 can cycle through the environment and food chain via water, soil, and insect. But cattle and *Salmonella enterica* serovar Typhimurium are considered to be the main reservoir for STEC [17–19]. In the United States, between 1998 and 2005, a majority of the STEC outbreaks were related to contaminated food and occurred in the period from May to October [20].

Considerable effort has been done to inhibit or facilitate infection of animals with STEC O157:H7, because of the readily transmission of pathogen strains such as EHEC in the farm environment and animals can even represent as vectors [21, 22].

However, illnesses caused by contaminated meat product still occur. But great effort has recently been placed on developing new strategies to control the widespread of distribution of EHEC serotypes, O157 and even non-O157 in cattle population to maintain their healthy condition and finally to decrease such illnesses in human [23].

Another practice for controlling is, by the use of beneficial bacteria often referred to as probiotics. Probiotics can interfere with pathogenic strains by producing metabolites that are inhibitory to STEC O157:H [24].

Some strains of *E. coli* strains can produce colicins that are inhibitory to STEC O157:H7 [25].
