Influence of animal production systems on the presence of pathogenic strains of Escherichia coli in the bovine production chain

Among the main pathogens involved in food outbreaks worldwide is diarrheagenic Escherichia coli (DEC). Cattle are considered natural reservoirs of DEC, and, during the slaughter stages, they can be a source of contamination for the carcass and final product. The objective of this work was to evaluate the influence of beef cattle production systems in Southeast Brazil, in the presence of diarrheagenic strains of Escherichia coli. A total of 485 samples were collected at the following points: post-bleeding (A), post-evisceration (B), post-final washing (C), meat cuts (D), bovine feces (F), surfaces (S), feces human (H) and wastewater (AR), from a cattle slaughterhouse, analyzing animals from two production systems: intensive and extensive. The samples were characterized in terms of pathotypes, phylogroups, and serogroups and analyzed using the chi-square test (p < 0.05). 126 samples were positive for E. coli, with points F (100%) and H (80%) being the points with the highest positivity. Only at point F was DEC identified (n = 35), with 28% of the animals in the intensive system and 38% in the extensive system positive for STEC, and 4% of the animals in the extensive system positive for EIEC, with no statistical difference between the production systems. Regarding phylogroups, B1 was the most detected in both systems, with 24% positivity in the intensive system and 68% in the extensive system. Serogroups O113 and O104 were detected, both in 4% of animals raised in an intensive system and in 6% of those in an extensive system. In view of the results, even with the identification of STEC and EIEC in the animals' feces, there was no difference between the rearing systems, with regard to pathotypes, phylogroups, and serogroups.