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 of Escherichia coli strains least resistant to antibiotics in penguins, whereas E. coli from 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 of E coli from Arctic birds (Bering Strait) revealed reduced susceptibility to antibiotics, but one globally spreading clone of E. coli genotype 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, with E. coli from birds showing resistance to a maximum of five different antibiotics. Presence of resistance-type ESBLs (TEM, SHV, and CTX-M) in E. coli and Klebsiella pneumoniae was 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.

Antibiotic resistance in bacterial isolates from freshwater samples in Fildes Peninsula, King George Island, Antarctica

“…These findings suggest that these ARGs were introduced by either humans or animals into zones A and B. Our results are congruent with previous reports, in which ESBLs genes were detected in isolates collected in regions near scientific bases in Antarctica and native bacteria did not present any ARGs 26 .…”

“…These results are in agreement with a previous report of ESBL-producing bacteria identified in freshwater samples collected in areas near the Bernardo O'Higgins (Antarctic Peninsula) and Arturo Prat (Greenwich Island) bases 25 . Even though the mechanisms of dissemination of ARGs in Antarctica are largely unknown, there is evidence that their spread is closely related to anthropogenic influence 26 and to the presence of migratory animals 11,27,28 . Moreover, previous studies detected multidrug-resistant bacteria recovered from penguin feces in Torgensen Island and in the Palmer Station (Anvers Island) 15 .…”

Occurrence and Genomic Characterization of ESBL-Producing, MCR-1-Harboring Escherichia coli in Farming Soil

“…The most prevalent bla CTX-M gene was bla CTX-M-14 ( n = 21), followed by bla CTX-M-27 ( n = 13), bla CTX-M-65 ( n = 10), bla CTX-M-55 ( n = 9), bla CTX-M-11 ( n = 2), and bla CTX-M-3 , bla CTX-M-15 , and bla CTX-M-17 ( n = 1 for each) (Supplementary Table S2 ). For E. coli in a clinical context, ST10, ST38, ST131, and ST405 are responsible for the dissemination of CTX-M worldwide ( Hernandez and Gonzalez-Acuna, 2016 ). The STs among the ESBL-producing E. coli observed in this study were quite different and only ST10 ( n = 2) was detected among the aforementioned STs.…”

Impact of human-associated Escherichia coli clonal groups in Antarctic pinnipeds: presence of ST73, ST95, ST141 and ST131

“…The Antarctic regions are regarded as protected areas with limited anthropogenic influence. However, there is growing concern about the impact of scientific and tourism activities which increase the risk of spreading human microorganisms in such relatively untouched ecosystems 1 . Marine mammals are considered as bio-indicators of possible environmental changes 2 , 3 but most studies focused on the effect of untreated sewage discharges next to research stations, with few data about the presence of human-associated microorganisms within these animals 4 .…”