title: Houseflies (Musca domestica) as Vectors for Extended-Spectrum β-Lactamase-Producing Escherichia coli on Spanish Broiler Farms.
abstract: Flies may act as potential vectors for the spread of resistant bacteria to different environments. This study was intended to evaluate the presence of Escherichia coli strains resistant to cephalosporins in flies captured in the areas surrounding five broiler farms. Phenotypic and molecular characterization of the resistant population was performed by different methods: MIC determination, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and phylotyping. The presence of extended-spectrum beta-lactamase (ESBL) genes, their plasmid location, and the mobile genetic elements involved in their mobilization were studied. Additionally, the presence of 35 genes associated with virulence was evaluated. Out of 682 flies captured, 42 yielded ESBL-producing E. coli. Of these isolates, 23 contained bla(CTX-M-1), 18 contained bla(CTX-M-14), and 1 contained bla(CTX-M-9). ESBL genes were associated mainly with the presence of the IncI1 and IncFIB replicons. Additionally, all the strains were multiresistant, and five of them also harbored qnrS. Identical PFGE profiles were found for E. coli isolates obtained from flies at different sampling times, indicating a persistence of the same clones in the farm environment over months. According to their virulence genes, 81% of the isolates were considered avian-pathogenic E. coli (APEC) and 29% were considered extraintestinal pathogenic E. coli (ExPEC). The entrance of flies into broiler houses constitutes a considerable risk for colonization of broilers with multidrug-resistant E. coli. ESBLs in flies reflect the contamination status of the farm environment. Additionally, this study demonstrates the potential contribution of flies to the dissemination of virulence and resistance genes into different ecological niches.
authors: Centre de Recerca en Sanitat Animal (CReSA)-Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Campus UAB, Barcelona, Spain.
authors: Marc
authors: M
authors: Solà-Ginés
authors: Servei de Microbiologia, Hospital Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors: Juan José
authors: JJ
authors: González-López
authors: Centre de Recerca en Sanitat Animal (CReSA)-Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Campus UAB, Barcelona, Spain.
authors: Karla
authors: K
authors: Cameron-Veas
authors: Servei de Microbiologia, Hospital Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors: Nuria
authors: N
authors: Piedra-Carrasco
authors: Centre de Recerca en Sanitat Animal (CReSA)-Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Campus UAB, Barcelona, Spain.
authors: Marta
authors: M
authors: Cerdà-Cuéllar
authors: Centre de Recerca en Sanitat Animal (CReSA)-Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Campus UAB, Barcelona, Spain lourdes.migura@irta.cat.
authors: Lourdes
authors: L
authors: Migura-Garcia
mesh_terms: D000383:Agriculture; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology*; D004199:Disease Vectors; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D006793:Houseflies / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011200:Poultry; D013030:Spain; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D001618:beta-Lactamases