Caracterização anátomo-histopatológica de fígados de frangos contaminados por Escherichia coli provenientes de matadouros avícolas da Bahia

Abstract

The aim of this study was to analyze anatomopathological lesions of chicken’s liver contaminated with Escherichia coli at poultry slaughterhouses. 62 liver samples were collected, under the supervision of the State Inspection Service at two poultry slaughterhouses situated in Recôncavo of Bahia. 30 livers did not show any macroscopic alterations and those who presented (n-32) had their carcass retained for further analyses (inspection line B). Macroscopic alterations included septicemia (36%), ascites (26%), colibacillosis (19%), cachexia (13%) and sacculitis (6%). Collected samples were aseptically packed in sterile containers, and then, they were identified, refrigerated and sent to the Microbiology Laboratory of Healthy Science Center at Federal University of Recôncavo of Bahia where they were immediately carried out for microbiological and macroscopic analyses. Pathological examinations were performed at the Laboratory of Pathology of Veterinary School at Federal University of Bahia. For microbiological analysis step enrichment in Brain Heart Infusion (BHI) were performed, followed by seeding streaks in McConkey agar and biochemical identification. Isolates were stocked in BHI with 15% glycerol and kept at -20oC for later extraction of bacterial DNA to perform the Polymerase Chain Reaction (PCR) performed at the Laboratory of Molecular Biology of the Instituto Materno Infantil de Pernambuco. Thirty Escherichia coli were isolated and identified in livers of chickens by classical microbiological method, 21 samples were unchanged and 9 from carcasses were rejected. The 30 E. coli isolates were from 27 poultry livers, because of a mixed infection of Avian Pathogenic E. coli (APEC) and Enterohaemorrhagic E. coli (EHEC) in three samples. Among the observed macroscopic parameters, the most common color of the samples was a dark brown (20/27), which were considered satisfactory. Cholangiohepatitis (16/27) was the predominant in inflammatory change, and was considered multifocal in 15/16 livers. Heterophils and mononuclear cells were predominant (12/27). PCR was performed verifing E. coli virulence genes, including the following genes: serum resistance (iss), for identification of APEC; Shiga cytotoxin 1 and 2 (stx), for identification of EHEC; bfpA, for identification of Enteropathogenic E. coli (EPEC); LT-I (elt) and ST-I (stI) toxins, for identification of Enterotoxigenic E. coli (ETEC). There wasn’t identification of genes bfpA, elt and stI. Iss gene was identified in 83.3% (25/30), and 76.2% (16/21) from E. coli strains isolated from livers from healthy animals. Stx gene was identified in 13.3% (4/30) of E. coli isolates, and in three of these samples were identified stx and iss. The genes were not identified in one E. coli isolated from classic method. The criteria for condemnation of carcasses were inadequate, because pathogenic Escherichia coli presence in 18/27 liver samples analyzed were from apparently healthy animals. It is necessary to adopt a protocol in the poultry slaughterhouses, which included necropsy, microbiological and serological analysis of a sample from rejected and healthy poultry, allowing a more accurate diagnosis and identification of pathogens. Safety procedures in farms and slaughterhouses are remarkable necessary for poultry health and safe food production.