August 29, 2016
1 min read

Companion animals may harbor mcr-1 gene, pass it to humans

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Researchers are suggesting another possible reservoir and mode of transmission for the colistin-resistant mcr-1 gene that has heightened fears about antimicrobial resistance: companion animals.

The mcr-1 gene already has been detected in humans, food and food animals, and recently was detected in the United States for the first time in two Escherichia coli isolates.

Now, the university scientists who studied three patients at a hospital in Guangzhou, China, said in a letter to Emerging Infectious Diseases that companion animals such as dogs and cats also may harbor the plasmid-mediated gene, and that it can be transmitted between the animals and humans.

Researchers suggest that companion animals such as dogs may be reservoirs for the colistin-resistant mcr-1 gene.


They tested the feces of 39 dogs and 14 cats at the pet shop where one of the patients, a man aged 50 years, worked, and found that four dogs and two cats had E. coli isolates that harbored mcr-1 — all of them resistant to colistin and other antibiotics.

Further tests showed that isolates from all four dogs and the urine of the pet shop worker were the same sequence type, and all five were clonally related, suggesting that E. coli harboring the mcr-1 gene was transmitted between them, the researchers said.

In the U.S., the mcr-1 genes detected in E. coli isolates from New York and Pennsylvania were both susceptible to other antimicrobial classes. The fear, however, is that the gene will jump to a bacteria species that is already resistant to most antibiotics.

“These findings suggest that mcr-1–producing E. coli can colonize companion animals and be transferred between companion animals and humans,” the researchers from China and the US wrote. “The findings also suggest that, in addition to food animals and humans, companion animals can serve as a reservoir of colistin-resistant E. coli, adding another layer of complexity to the rapidly evolving epidemiology of plasmid-mediated colistin resistance in the community.”by Gerard Gallagher

Disclosure: The researchers report no relevant financial disclosures.