Bacteria and viruses in our food are the most common cause of food poisoning. Symptoms and severity of poisoning vary, but some of the most notorious bacteria that infect our food are E.coli (recently found in spinach) and listeria (recently discovered in ice cream). Yet another type of harmful bacteria has been found in our food supply and some strains of it are resistant to antibiotics, according to a new study.

Researchers at the Milken Institute School of Public Health and others compared turkey, chicken, and pork samples from grocery stores in Flagstaff, Ariz., to urine and blood samples of people infected by Klebsiella pneumoniae. Analysis showed that about 47 percent of the meat samples tested positive for the bacteria, and some of the samples sequenced were nearly identical to the human strains.

The government does not currently test food for K. pneumoniae. Some of the strains discovered in the samples were resistant to antibiotics, highlighting the need for more judicious use of antibiotic use in livestock.

The study cannot prove that the strains found in human samples came from a grocery store.

“What we can say is that there were strains that were isolated from people and from meat that were nearly indistinguishable,” said lead study author Lance B. Price, a professor of environmental and occupational health at Milken Institute School of Public Health, in an email to Time.

Price also pointed out that most of the meat products were produced out of state, meaning that this problem is not limited to Arizona.

More On Klebsiella Pneumoniae

Klebsiella pneumoniae is a type of bacteria that can cause a variety of infections in humans. Included in these is pneumonia, bloodstream infections, meningitis, and wound or surgical site infections. K. pneumoniae can normally be found in the human intestines, where they do not cause disease. Healthy people do not normally become infected by K. pneumoniae — it occurs most often in those being treated for other conditions and those on long courses of antibiotics.

The bacteria is generally spread through the respiratory system, having been spread through person-to-person contact, contamination of the environment, or through medical devices such as ventilators and intravenous catheters.

Certain strains of K. Pneumoniae have become difficult to treat due to drug resistance. In cases like this, laboratories will have to run additional tests on a patient to determine which antibiotics will actually have an effect on the bacteria.

Source: Price L, Davis G, Waits K, Nordstrom L, Weaver B, Aziz M, et al. Intermingled Klebsiella pneumoniae populations between retail meats and human urinary tract infections. Clinical Infectious Diseases. 2015.