Aim: The purpose of this study was to determine serotypes, virulence genes and phylogenetic groups of Escherichia coli isolated from breeders, broiler flocks (progeny of the same breeder flock) and their carcasses, of three different production chains (A, B, and C). Sampling was carried out during the period of January 2017 to January 2018 in Northern Italy. Methods: A total of 153 E. coli strains were isolated from flocks (12 from breeders, 38 from chicks, 65 from broilers) and slaughterhouse (38 DOA birds). Tissue/organ samples (e.g. air sacs, lungs, brain, liver and pericardium) were collected from lesions suggestive of colibacillosis such as airsacculitis, cellulitis, pericarditis and perihepatitis. All isolates were serogrouped by standard slide agglutination test with sera against the O-somatic antigens: O1, O2 and O78. A multiplex PCR targeting five virulence genes (iroN, ompT, hlyF, iss and iutA) for APEC. Phylogroups were determined by quadruplex (A, A/C, B1, B2, D/E, F) and single (C, E) PCRs. Results: Out of 153 isolates, 73 were successfully serotyped and among these 56 (76.71%) belonged to the O78 serotype, 9 (12.32%) to the O2 serotype and 8 (10.95%) to the O1 serotype. All isolates carried two APEC virulence genes (iroN and iutA). The examined isolates belonged to seven different phylogenetic groups: 53 to A (34.64%), 6 to B1 (3.92%), 1 to B2 (0.65%), 64 to C (41.83 %), 5 to D (3.26%), 1 to E (0.65%) and 27 to F (17.64%) phylogroups. The frequency of phylogroups comprised 44.23%, 35.52% and 22.22% belonging A, C and F, respectively, and these were predominant in chicks, broilers, and DOA birds in the three production chains (serogroup O78). Conclusion: This study indicates that no difference in virulence genes was present among APEC isolates. In particular, A, C and F phylogroups were predominant, representing O78 serogroup, which is mainly associated with invasive and often lethal disease in poultry. Neverthless, our results recommend further investigations into APEC isolates to determine all serogroups and examine genetic diversity to refine the definition of related flock in the broiler production chain.

Avian Pathogenic Escherichia coli in the poultry industry: analysis of serotypes, phylogroups and virulence markers.

Apostolakos I.;Piccirillo A.
2018

Abstract

Aim: The purpose of this study was to determine serotypes, virulence genes and phylogenetic groups of Escherichia coli isolated from breeders, broiler flocks (progeny of the same breeder flock) and their carcasses, of three different production chains (A, B, and C). Sampling was carried out during the period of January 2017 to January 2018 in Northern Italy. Methods: A total of 153 E. coli strains were isolated from flocks (12 from breeders, 38 from chicks, 65 from broilers) and slaughterhouse (38 DOA birds). Tissue/organ samples (e.g. air sacs, lungs, brain, liver and pericardium) were collected from lesions suggestive of colibacillosis such as airsacculitis, cellulitis, pericarditis and perihepatitis. All isolates were serogrouped by standard slide agglutination test with sera against the O-somatic antigens: O1, O2 and O78. A multiplex PCR targeting five virulence genes (iroN, ompT, hlyF, iss and iutA) for APEC. Phylogroups were determined by quadruplex (A, A/C, B1, B2, D/E, F) and single (C, E) PCRs. Results: Out of 153 isolates, 73 were successfully serotyped and among these 56 (76.71%) belonged to the O78 serotype, 9 (12.32%) to the O2 serotype and 8 (10.95%) to the O1 serotype. All isolates carried two APEC virulence genes (iroN and iutA). The examined isolates belonged to seven different phylogenetic groups: 53 to A (34.64%), 6 to B1 (3.92%), 1 to B2 (0.65%), 64 to C (41.83 %), 5 to D (3.26%), 1 to E (0.65%) and 27 to F (17.64%) phylogroups. The frequency of phylogroups comprised 44.23%, 35.52% and 22.22% belonging A, C and F, respectively, and these were predominant in chicks, broilers, and DOA birds in the three production chains (serogroup O78). Conclusion: This study indicates that no difference in virulence genes was present among APEC isolates. In particular, A, C and F phylogroups were predominant, representing O78 serogroup, which is mainly associated with invasive and often lethal disease in poultry. Neverthless, our results recommend further investigations into APEC isolates to determine all serogroups and examine genetic diversity to refine the definition of related flock in the broiler production chain.
2018
Pathogenic Escherichia coli in the poultry industry: analysis of serotypes, phylogroups and virulence markers. Proceedings of the 2nd International Congress of Veterinary Microbiology
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