Detection and characterization of avian pathogenic Escherichia coli (APEC) in backyard chickens creation

Author(s)

Elisabete Schirato de Oliveira

• Document type: Doctoral Thesis
• Press: Jaboticabal. 2017-01-09.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2016-12-15
• Advisor: Fernando Antônio de Ávila

Abstract

The conditions of backyard chickens creation (BC) present a high sanitary risk, since biosafety measures are not always implemented in these systems. Among the most important infectious disease in poultry is colibacillosis, and avian pathogenic Escherichia coli (APEC) is the causative agent. This disease is related to the way and environment in which these birds are created, and some APEC isolates can cause infection in birds and humans. The virulence mechanism of APEC samples has been continuously studied and probably is multifactorial. The objective of this work was to detect and characterize potentially APEC isolates in BC creations. For that, it were collected cloacal and oropharyngeal samples of 250 BC, from seven small properties from Ribeirão Preto - SP. Of the 500 samples, 69 positive E. coli isolates were obtained for at least 5 characteristic genes of APEC. These isolates were submitted to PCR for detection of 11 more virulence genes, resulting in a high prevalence of them. The test of inoculation in one day-old chicks revealed that 49 of these isolates had high and/or intermediate pathogenicity. All isolates were also submitted to the susceptibility testing on 17 antimicrobials, and showed resistance to at least one antimicrobial agent, but the most of them (79.7%) had a multiresistance profile. In addition, phylogenetic analysis was performed and 53.6% of the isolates belonged to B2 group, which has already been described as the group harboring isolates that cause extraintestinal infections. In pulsified gel electrophoresis analysis (PFGE), it was detected a high heterogeneity of pulse types among the APEC isolates and only one sample was non-typable for XbaI enzyme. Furthermore, 15 serogroups were identified among the isolates, and O8 was the most frequent (23.2%). The results obtained in this study demonstrated that BC are APEC reservoirs with zoonotic potential, multiresistant to antimicrobials, potentially pathogenic to birds and carrying a large number of virulence genes, which represents a high risk for chickens and also humans who have contact with these animals or consume food derived from them. (AU)

• FAPESP's process: 13/18279-1 - Detection and characterization of Escherichia coli avian pathogenic (APEC) in domestic backyard poultry in the region of Ribeirão Preto-SP
• Grantee: Elisabete Schirato de Oliveira
• Support Opportunities: Scholarships in Brazil - Doctorate