title: Molecular characterization and genetic diversity of ESBL-producing Escherichia coli colonizing the migratory Franklin's gulls (Leucophaeus pipixcan) in Antofagasta, North of Chile.
abstract: The role of wild animals, particularly migratory birds, in the dissemination of antibiotic-resistant bacteria between geographically distant ecosystems is usually underestimated. The aim of this work was to characterize the Escherichia coli population from Franklin's gull feces, focusing on the extended-spectrum β-lactamase (ESBL)-producing strains. In the summer of 2011, 124 fecal swabs from seagulls (1 of each) migrating from the United States and Canada to the coast of Antofagasta, north of Chile, were collected. Samples were seeded on MacConkey agar supplemented with 2 μg/ml of cefotaxime and a single colony from each plate was tested for ESBL production by the double-disk ESBL synergy test. Antibiotic susceptibility was determined by the disk diffusion method and blaESBL genes were amplified and sequenced. The genetic diversity of isolates was explored by pulsed-field gel electrophoresis (PFGE)-XbaI and multilocus sequence typing. A total of 91 E. coli isolates with high rates of antibiotic resistance were identified. Carbapenemase production was not detected, whereas 67 of the 91 (54%) isolates exhibited an ESBL phenotype due to the presence of CTX-M-15 (61.3%), CTX-M-2 (19.3%), CTX-M-22 (16.1%), and CTX-M-3 (1.6%) coding genes. High genetic diversity was observed, with 30 PFGE patterns and 23 sequence types (STs), including ST131 (18%), ST44 (15%), ST617 (9%), and ST10 (9%). Results presented here are complementary to those previously reported by Hernández et al. in the same gull species, but located in the Central Region of Chile. Differences observed between gulls from both areas lead us to hypothesize that gulls from the northern location retain, as gut carriers, those resistant bacteria acquired in the United States and/or Canada.
authors.affiliation: 1 Departamento de Tecnología Médica, Universidad de Antofagasta , Antofagasta, Chile .
authors.forename: John
authors.initials: J
authors.lastname: Báez
authors.forename: Marta
authors.initials: M
authors.lastname: Hernández-García
authors.forename: Constanza
authors.initials: C
authors.lastname: Guamparito
authors.forename: Sofía
authors.initials: S
authors.lastname: Díaz
authors.forename: Abdon
authors.initials: A
authors.lastname: Olave
authors.forename: Katherine
authors.initials: K
authors.lastname: Guerrero
authors.forename: Rafael
authors.initials: R
authors.lastname: Cantón
authors.forename: Fernando
authors.initials: F
authors.lastname: Baquero
authors.forename: Joselyne
authors.initials: J
authors.lastname: Gahona
authors.forename: Nicomedes
authors.initials: N
authors.lastname: Valenzuela
authors.forename: Rosa
authors.initials: R
authors.lastname: Del Campo
authors.forename: Juan
authors.initials: J
authors.lastname: Silva
mesh_terms: D025041:Animal Migration; D000818:Animals; D046091:Charadriiformes / Q000382:microbiology*; D002677:Chile; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D029968:Escherichia coli Proteins / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D005798:Genes, Bacterial; D014644:Genetic Variation; D007422:Intestines / Q000382:microbiology; D058885:Multilocus Sequence Typing; D009656:North America; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D029968:Escherichia coli Proteins; D001618:beta-Lactamases