Those who are concerned about what might be lurking in the meat they purchase have a reason to worry, according to a new study.

The study sampled meat from grocery stores throughout five U.S. cities and the results were remarkable. 47 percent of the meat sampled contained Staphyloccus aureus. Over half of that 47 percent contained a strain what was resistant to antibiotics.

S. aureus is a bacteria that can cause a variety of problems including skin infection, pneumonia and even sepsis. The study found the bacteria in all forms of meat including beef, chicken, pork and turkey.

Lance Price, senior author of the study, noted how substantial the amount of infected meat was. He says the fact that the bacteria is resistant to antibiotics calls for attention into how antibiotics are being used in food animal processing. Price indicated that the resistance likely stems from farms that feed the animals low doses of the antibiotics.

The bacteria can often be killed by cooking the meat, but there is still a high risk for contamination. Handling the meat or not fully cooking it can lead  infection. This alarming amount of contamination in the meat supply may account for the over two million people who are infected in the U.S. each year.

The study tested 136 samples from 80 brands of meat at 26 grocery stores in 5 U.S. cities.

Co-author Paul Keim says the next step is determining what the risk is to the consumer from this new information.