title: Anthropogenic antibiotic resistance genes mobilization to the polar regions.
abstract: Anthropogenic influences in the southern polar region have been rare, but lately microorganisms associated with humans have reached Antarctica, possibly from military bases, fishing boats, scientific expeditions, and/or ship-borne tourism. Studies of seawater in areas of human intervention and proximal to fresh penguin feces revealed the presence ofEscherichia colistrains least resistant to antibiotics in penguins, whereasE. colifrom seawater elsewhere showed resistance to one or more of the following antibiotics: ampicillin, tetracycline, streptomycin, and trim-sulfa. In seawater samples, bacteria were found carrying extended-spectrum β-lactamase (ESBL)-type CTX-M genes in which multilocus sequencing typing (MLST) showed different sequence types (STs), previously reported in humans. In the Arctic, on the contrary, people have been present for a long time, and the presence of antibiotic resistance genes (ARGs) appears to be much more wide-spread than was previously reported. Studies ofE colifrom Arctic birds (Bering Strait) revealed reduced susceptibility to antibiotics, but one globally spreading clone ofE. coligenotype O25b-ST131, carrying genes of ESBL-type CTX-M, was identified. In the few years between sample collections in the same area, differences in resistance pattern were observed, withE. colifrom birds showing resistance to a maximum of five different antibiotics. Presence of resistance-type ESBLs (TEM, SHV, and CTX-M) inE. coliandKlebsiella pneumoniaewas also confirmed by specified PCR methods. MLST revealed that those bacteria carried STs that connect them to previously described strains in humans. In conclusion, bacteria previously related to humans could be found in relatively pristine environments, and presently human-associated, antibiotic-resistant bacteria have reached a high global level of distribution that they are now found even in the polar regions.
authors.affiliation: Department of Medical Sciences, Uppsala University, Uppsala, Sweden.|Clinic of Microbiology, Kalmar County Hospital, Kalmar, Sweden; jorge.hernandez@lnu.se.
authors.forename: Jorge
authors.initials: J
authors.lastname: Hernández
authors.affiliation: Facultad de Ciencias Veterinarias, Universidad de Concepción, Concepción, Chile.
authors.forename: Daniel
authors.initials: D
authors.lastname: González-Acuña
keywords: CTX-M; E. coli; ESBL; Enterobacteriaceae; K. pneumoniae; antibiotic resistance genes; antibiotics; human-associated bacteria; polar regions; wildlife