Classification of avian pathogenic Escherichia coli by a novel pathogenicity index based on an animal model
Souza, Guilherme Fonseca deRocha, Silvio Luís da SilveiraFurian, Thales QuediBorges, Karen ApellanisSalle, Felipe de OliveiraMoraes, Lucas Brunelli deMoraes, Hamilton Luiz de SouzaSalle, Carlos Tadeu Pippi
Background: Avian Pathogenic Escherichia coli is the main agent of colibacillosis, a systemic disease that causes considerable economic losses to the poultry industry. In vivo experiments are used to measure the ability of E. coli to be pathogenic. Generally, these experiments have proposed different criteria for results interpretation and did not take into account the death time. The aim of this study was to propose a new methodology for the classification of E. coli pathogenicity by the establishment of a pathogenicity index based in the lethality, death time and the ability of the strain to cause colibacillosis lesions in challenged animals. Materials, Methods & Results: A total of 293 isolates of E. coli were randomly selected to this study. The strains were isolated from cellulitis lesions, broiler bedding material or respiratory diseases and were previously confirmed through biochemical profile. The bacterial isolates were kept frozen at -20C. The strains were retrieved from stocks and cultured in brain-heart infusion broth overnight at 37C to obtain a final concentration of 109 UFC/mL. A total of 2940 one-dayold chicks from commercial breeding hens were randomly assigned to groups containing 10 animals and each group was subcutaneously inoculated in the abdominal region with 0.1 mL of the standard inoculum solution containing each of the strains. A control group [...](AU)
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