The researchers from Sweden studied antimicrobial drug resistance in Escherichia coli isolated from Arctic birds to 17 antimicrobial drugs, detecting resistance to 14 of them.

“We were extremely surprised,” said Björn Olsen, Professor of Infectious Diseases at Uppsala University and at the Laboratory for Zoonosis Research at the University of Kalmar.

“We took samples from birds living far out on the tundra and had no contact with people. This further confirms that resistance to antibiotics has become a global phenomenon and that virtually no region of the earth, with the possible exception of the Antarctic, is unaffected.”

The team took samples from 97 birds in north-eastern Siberia, northern Alaska, and northern Greenland and cultivated them directly in laboratories the researchers had installed onboard the icebreaking ship they used to reach the Arctic. Samples were further analysed at the microbiological laboratory at the Central Hospital in Växjö, Sweden.

The researchers suggest the reason for the resistance is that immigrating birds have passed through regions in Southeast Asia, for example, where there is a great deal of antibiotic pressure and carried with them the resistant bacteria to the tundra.

Professor Olsen told Laboratory News: “The fact that an isolate from a juvenile Western sandpiper sampled far from human settlements on the tundra had resistance to cefadroxil, cefuroxime, and cefpodoxime, a resistance pattern commonly seen in clinical isolates, supports the theory of introduction by migration and transfer of bacteria between birds.”

In a paper published in the journal Emerging Infectious Diseases, the team goes further to suggest that migrating birds carrying antibiotic-resistant bacteria can then infect isolated human communities, using the Bolivian community of 130 Guaraní Indians as an example. This community is located at an altitude of 1,700m and can only be reached by a 3-hour steep climb. Nevertheless, high rates of drug-resistant E. coli were found in this community, although exposure to antimicrobial drugs in the area had been limited.

“A possible explanation for the unexpectedly high carriage rate of drug-resistant E. coli in the Indian community in Bolivia is the importation of drug-resistant isolates by migratory birds,” said Jonas Bonnedahl, a physician specialising in infectious diseases in Kalmar and one of those participating in the expedition.

He added: “Our findings show that resistance to antibiotics is not limited to society and hospitals but is now spreading into the wild. Escalating resistance to antibiotics over the last few years has crystallised into one of the greatest threats to well-functioning health care in the future.”