title: Class 1 and class 2 integrons in avian pathogenic Escherichia coli from poultry in Italy.
abstract: The aim of this study was to investigate the occurrence of class 1 and 2 integrons in avian pathogenic Escherichia coli (APEC) from poultry in northern Italy. Strains were tested for phenotypic resistance to aminoglycosides and sulphonamides, and the association between the presence of integrons and the resistance to these antimicrobials was evaluated. A total of 299 isolates (158 from turkeys, 110 from broilers, and 31 from layer hens) were collected from 200 industrial farms. Antimicrobial susceptibility test by the disk diffusion method was performed in accordance with the Clinical and Laboratory Standards Institute (CLSI) guidelines. All strains were screened for the presence of class 1 and 2 integrons by PCR and sequencing. About 55% of APEC contained integrons (class 1, 49.8%; class 2, 10.4%). Different variants of the aadA (5 variants) and the dfrA (4 variants) genes, encoding for streptomycin and trimethoprim resistance respectively, were detected in integron-positive isolates. Less common gene cassettes, such as sat, estX, and orfF, were also identified. Fifteen and 4 gene cassette arrays were found among class 1 and 2 integrons, respectively. High levels of resistance were observed for triple sulphonamides (79.3%), streptomycin (67.2%), and sulfamethoxazole combined with trimethoprim (62.2%), whereas resistance against gentamycin (16.7%), kanamycin (14.7%), and apramycin 3.0%) was low. Integron positivity was significantly higher in isolates phenotypically resistant to aminoglycosides (63.6% vs. 37.8%, P<0.001) and sulfonamides (64.1% vs. 21.1%, P<0.001) than in susceptible ones. Integron-borne aminoglycoside and sulfonamide resistance in APEC represents a concern for the poultry industry in Italy, since they are among the most commonly used antimicrobials in poultry therapy.
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, 35020 Legnaro (PD), Italy.
authors.forename: Lara
authors.initials: L
authors.lastname: Cavicchio
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, 35020 Legnaro (PD), Italy.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Dotto
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, 35020 Legnaro (PD), Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Giacomelli
authors.affiliation: Laboratorio Tre Valli, 37132 San Michele Extra (VR), Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Giovanardi
authors.affiliation: Department of Veterinary Science and Public Health, University of Milan, 20133 Milano, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Grilli
authors.affiliation: Department of Biopathologic Science and Hygiene of Food and Animal Production, University of Perugia, 06126 Perugia, Italy.
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Franciosini
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, 35020 Legnaro (PD), Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Trocino
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, 35020 Legnaro (PD), Italy alessandra.piccirillo@unipd.it.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Piccirillo
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002645:Chickens; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology / Q000662:veterinary; D005260:Female; D032023:Integrons; D007558:Italy; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D011201:Poultry Diseases / Q000453:epidemiology* / Q000382:microbiology; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D013449:Sulfonamides / Q000494:pharmacology; D014422:Turkeys
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D013449:Sulfonamides
keywords: aminoglycoside; antimicrobial resistance; avian pathogenic Escherichia coli; integron; poultry; sulfonamide