Inside the guts of city mice dwell potentially harmful germs — and in New York City, 23 percent of mice tested positive for at least one antimicrobial-resistant gene, according to a study published in mBio.
In the largest survey of microorganisms living in city mice, the researchers trapped over 400 of the rodents across four of New York City's boroughs and identified number of genes in these animals that give germs resistance to antibiotic drugs. The majority of the study's mice resided in trash compactor rooms in apartment building basements.
"This doesn't tell us that these mice are directly responsible for infecting humans," study author W. Ian Lipkin, MD, director of New York City-based Columbia University's Center for Infection and Immunity, told The Washington Post. "But they have the potential to do so."
Based on the mice's fecal matter and anal swab samples, the study found 37 percent of the mice contained at least one bacterial pathogen, including Clostridium difficile, salmonella and Escherichia coli. About 1 in 4 of the mice (23 percent) tested positive for at least one antimicrobial-resistant gene.
The researchers anticipate similar bacteria in mice residing in other urban areas. "I would suspect that if you looked in Washington, D.C., or Boston or Toronto, you'd have similar findings," Dr. Lipkin said.
Hospitals have long reported drug-resistant germs, where antibiotics are routinely administered and surviving bacteria are more likely to thrive. "The drugs that we have been using successfully since the 1940s have been losing their potency," Dr. Lipkin said.
Mice are especially important animals to study when considering their close contact with human living spaces, according to Dr. Lipkin.
Dr. Lipkin said he hoped the study helped highlight the significant of rodent control in public health efforts. "This is something that people need to take seriously."