Yuck! Study Reveals NYC House Mice Droppings Carry Antibiotic-Resistant Germs and Deadly Disease-Causing Bacteria

Researchers discovered that the droppings of New York City house mice carry bacteria and unknown viruses capable of causing fever and even life-threatening gastrointestinal diseases in humans.

In the report “Of Mice and Disease: Antibiotic-Resistant Bacteria Discovered in NYC Mice,” scientists at Columbia University’s Mailman School of Public Health also identified that house mice in the city possess several genes enabling antimicrobial resistance to antibiotics.

Researchers collected 416 mice from New York City apartments in Manhattan, Queens, Brooklyn and the Bronx over the span of a year. A genetic analysis of their droppings revealed that the mice carry a number of gastrointestinal disease-causing bacteria, including C. difficile, E. coli, Shigella, as well as Salmonella. Salmonella is a leading cause of bacterial food poisoning in the United States with 1.4 million reported cases a year along with 15,000 hospitalizations and 400 deaths.

According to researchers, salmonella infections can be the result of food contaminated with animal waste, including mice droppings. C. difficile infections, while generally acquired in healthcare settings, could also be spread in the community by the mice that harbor the pathogens.

“Mice are more than just a nuisance — they are a potential source of infections,” Ian Lipkin, director of the Center for Infection and Immunity at Columbia University’s Mailman School of Public Health and senior researcher, said in a statement.

The researchers also found evidence of genes facilitating antimicrobial resistance to several common antibiotics, including quinolones and macrolides.

“Our study raises the possibility that serious infections — including those resistant to antibiotics —may be passed from these mice to humans, although further research is needed to understand how often this happens, if at all,” Simon Williams, a research scientist at the Center for Infection and Immunity and lead author of the studies, said in a statement.

In a second study, the team identified 36 viruses in the mice’s fecal matter, including six new viruses, none of which are known to infect humans. However, the team did identify genetic sequences found in viruses that infect dogs, chickens and pigs, which suggests the possibility that some of the viruses had crossed over from other species, the researchers say.

The researchers also discovered that city’s house mice harbored bacteria with 22 different genes that could result in the resistance of a number of common antibiotic drugs.

“My concern is that they are a reservoir of antibiotic resistance,” Lipkin said, adding that if humans were infected by a bacterial strain carried by these mice, the infection could be resistant to treatment.

Mice from Chelsea, which tend to be heavier than mice from other locations, also carried more viruses, the studies found.

Overall, the team of scientists documented that 37 percent of the mice carried at least one potentially pathogenic bacterium and 23 percent of the mice harbored at least one antimicrobial resistance gene in their fecal bacteria.