title: Carriage of CTX-M type extended spectrum β-lactamases (ESBLs) in gulls across Europe.
abstract: BACKGROUND
  Extended spectrum β-lactamases (ESBLs), a group of enzymes conferring resistance to third generation cephalosporins have rapidly increased in Enterobacteriacae and pose a major challenge to human health care. Resistant isolates are common in domestic animals and clinical settings, but prevalence and genotype distribution varies on a geographical scale. Although ESBL genes are frequently detected in bacteria isolated from wildlife samples, ESBL dissemination of resistant bacteria to the environment is largely unknown. To address this, we used three closely related gull species as a model system and collected more than 3000 faecal samples during breeding times in nine European countries. Samples were screened for ESBL-producing bacteria, which were characterized to the level of ESBL genotype groups (SHV, TEM), or specific genotypes (CTX-M).
  
  
  RESULTS
  ESBL-producing bacteria were frequently detected in gulls (906 of 3158 samples, 28.7 %), with significant variation in prevalence rates between countries. Highest levels were found in Spain (74.8 %), The Netherlands (37.8 %) and England (27.1 %). Denmark and Poland represented the other extreme with no, or very few positive samples. Genotyping of CTX-M isolates identified 13 different variants, with bla CTX-M-1 and bla CTX-M-14 as the most frequently detected. In samples from England, Spain and Portugal, bla CTX-M-14 dominated, while in the rest of the sampled countries bla CTX-M-1 (except Sweden where bla CTX-M-15 was dominant) was the most frequently detected genotype, a pattern similar to what is known from studies of human materials.
  
  
  CONCLUSIONS
  CTX-M type ESBLs are common in the faecal microbiota from gulls across Europe. The gull ESBL genotype distribution was in large similar to published datasets from human and food-production animals in Europe. The data suggests that the environmental dissemination of ESBL is high from anthropogenic sources, and widespread occurrence of resistant bacteria in common migratory bird species utilizing urban and agricultural areas suggests that antibiotic resistance genes may also be spread through birds.
authors.affiliation: Centre for Ecology and Evolution in Microbial Model Systems, School of Natural Sciences, Linnaeus University, 391 82, Kalmar, Sweden. johan.stedt@lnu.se.
authors.forename: Johan
authors.initials: J
authors.lastname: Stedt
authors.affiliation: Department of Infectious Diseases, Kalmar County Hospital, 391 85, Kalmar, Sweden. jonas.bonnedahl@ltkalmar.se.|Section of Clinical Microbiology and Infectious Diseases, Department of Medical Sciences, Uppsala University, 751 85, Uppsala, Sweden. jonas.bonnedahl@ltkalmar.se.
authors.forename: Jonas
authors.initials: J
authors.lastname: Bonnedahl
authors.affiliation: Section of Clinical Microbiology and Infectious Diseases, Department of Medical Sciences, Uppsala University, 751 85, Uppsala, Sweden. Jorge.hernandez@lnu.se.
authors.forename: Jorge
authors.initials: J
authors.lastname: Hernandez
authors.affiliation: Centre for Ecology and Evolution in Microbial Model Systems, School of Natural Sciences, Linnaeus University, 391 82, Kalmar, Sweden. jonas.waldenstrom@lnu.se.
authors.forename: Jonas
authors.initials: J
authors.lastname: Waldenström
authors.affiliation: UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland. barry.mcmahon@ucd.ie.
authors.forename: Barry J
authors.initials: BJ
authors.lastname: McMahon
authors.affiliation: Centre for Ecology and Evolution in Microbial Model Systems, School of Natural Sciences, Linnaeus University, 391 82, Kalmar, Sweden. conny.tolf@lnu.se.
authors.forename: Conny
authors.initials: C
authors.lastname: Tolf
authors.affiliation: Section of Clinical Microbiology and Infectious Diseases, Department of Medical Sciences, Uppsala University, 751 85, Uppsala, Sweden. bjorn.olsen@medsci.uu.se.
authors.forename: Björn
authors.initials: B
authors.lastname: Olsen
authors.affiliation: Section of Clinical Microbiology and Infectious Diseases, Department of Medical Sciences, Uppsala University, 751 85, Uppsala, Sweden. mirva.drobni@regionjh.se.|Department of Laboratory Medicine, Clinical Microbiology, Östersund Hospital, 831 83, Östersund, Sweden. mirva.drobni@regionjh.se.
authors.forename: Mirva
authors.initials: M
authors.lastname: Drobni
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D046091:Charadriiformes / Q000382:microbiology*; D005060:Europe; D005243:Feces / Q000382:microbiology; D005838:Genotype; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases