New York City mice were found to carry all sorts of human diseases.
Mice were collected at seven sites in Manhattan, Queens, Brooklyn, and the Bronx over a period of 1 year.
"From tiny studios to penthouse suites, New York City apartments are continually invaded by house mice", says lead author Simon H. Williams, a research scientist at the Center for Infection and Immunity at Columbia University.
"We found a lot of antibiotic resistance in some of these bacteria, which we think may have implications for understanding not only the ubiquity of antibiotic-resistant bacteria in the environment but also potential sources of human infection", said Lipkin, whose research was published Tuesday in the journal mBio. Salmonella is traditionally transmitted via the fecal-oral route - mostly with food contaminated with animal feces.
The critters Lipkin's group studied did not seem be affected by their infections, so it's possible that at least some mice may be able to tolerate the bugs and act as carriers for the bacteria, spreading them from building to building as they travel throughout a city like NY.
The mice appeared to be healthy, and Dr. Lipkin said he presumes that they are carriers of the bacteria but are not affected by them. None of the viruses, however, are known to infect humans.
"Does a resistant bug in a mouse pose a risk to a person in the house?"
When they dug deeper, the investigators found evidence of genes that can make the bacteria resistant to common antibiotics. Primarily, the scientists caught the mice in or around garbage disposal areas in sub-basements, though five mice were trapped in food preparation/storage areas of a commercial building, and a single mouse was imprisoned in a private apartment.More news: Supreme Court hears case about online sales tax collection
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A previous study of rats in NY by CII investigators found some of the same pathogens, according to the university, like E. coli and Salmonella, both of which can be associated with food poisoning, and C. difficile, which causes symptoms like diarrhea and colitis, or inflammation of the colon. In total, about 37% of all the mice sampled carried some sort of potentially harmful bacteria, and about a quarter of them carried drug-resistant bacterial genes.
This research can not determine in which direction the germs had traveled - it was not known if the bacteria moved from humans to mice or mice to humans. However, they identified genetic sequences matching viruses that infect dogs, chickens, and pigs, suggesting the possibility that some of the viruses had crossed over from other species.
Antibiotic resistance is a prominent issue regarding animals.
Together, the findings show that mice may be an untapped reservoir of potentially risky infections, and suggest that mouse populations should be studied when outbreaks of such infections occur - just as mosquitoes are investigated when cases of West Nile or Zika start to surge. "They are not fed antibiotics, but they are carrying bacteria that are sometimes resistant to them".
Viney, who studies the immune responses of wild mice, noted that "an enormous amount is known about the immune responses of lab mice".
Lipkin acknowledged that it was perhaps unsurprising that mice would harbor these bacteria given the germs' omnipresence.
"This is a hard kind of study to do, logistically", Lipkin said.