Humans have spread antibiotic resistance so far and wide that diverse clusters of microbes with resistance genes are now turning up in the gut microbiome of penguins in Antarctica.
Antibiotic-resistance can occur naturally, and microbes with resistance genes have been found in before. Now we know the microbes are also present in the animals living on those soils.
Vanessa Marcelino at the University of Sydney, Australia, and her colleagues compared the diversity of gut microbes carrying antibiotic resistance genes in Gentoo penguins living around two Antarctic bases.
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Penguins near the busy O’Higgins Base carried more of the genes in their microbiome than those living near the smaller, less-populated Gabriel González Videla Base.
“Birds I think are maintaining those genes in the environment and distributing them around,” says Marcelino.
Swab their bums
The penguins’ microbiomes were examined as part of a broader study into birds that carry microbes with antibiotic resistance genes. The researchers took microbiome samples from 110 ducks and wading birds at sites in Antarctica and Australia. “You swab the bums of the birds,” says Marcelino.
RNA sequencing revealed the diversity and expression levels of known antibiotic-resistance genes.
The birds that had the greatest diversity of antibiotic-resistance genes were those that lived in the ponds of a sewage treatment plant in Melbourne. Filter-feeding ducks were more likely to carry lots of the genes than species accustomed to feeding in pristine waters.
The approach has impressed Josef Järhult at Uppsala University in Sweden. “It’s a more complex measure of how diverse, how big the pool of genetic resistance is,” he says. “It demonstrates really nicely the inter-linkage between humans and the environment which is very often overlooked in general,” says Järhult.
But Francois Balloux at University College London says more evidence is needed to directly tie the presence of this genetic material to human activity in the areas sampled. “There’s no pristine place on Earth as far as antimicrobial resistance is concerned,” he says.
BioRxiv
