Virologists found the rare mrc-1 gene, which causes the resistance, in a strain of E coli from a patient in New York, according to findings published in the journal Antimicrobial Agents and Chemotherapy.
"We are very close to seeing the emergence of enterobacteria that will be impossible to treat with antibiotics," said Lance Price of George Washington University.
The first US case of human infection with the gene-carrying E coli bacteria occurred in May, in a 49-year-old patient hospitalised in Pennsylvania with a urinary tract infection. She has since recovered.
The mrc-1 gene is especially dreaded because it makes bacteria resistant to colistin, the antibiotic of last resort for such infections.
The gene, located on a small fragment of microbial DNA, can move from one bacteria to another across several species, potentially spreading resistance to all antibiotics, which authorities see as a catastrophe scenario.
Scientists have been tracking the gene`s movements around the globe since its discovery in humans, poultry and pigs in China in 2015.
2nd American patient found with superbug resistant to antibiotics of last resort
28 June 2016
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A second American patient has been infected with a superbug that is highly resistant to antibiotics of last resort, scientists announced on Monday.
