NEW YORK - Researchers have found high levels of bacteria in meat commonly found on US grocery store shelves, with more than half of the bacteria resistant to multiple types of antibiotics, according to a study released on Friday.

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While the meat commonly found in grocery stores is still safe to eat, consumers should take precautions especially in handling and cooking, the chief researcher for the study said.

The study by the Arizona-based Translational Genomics Research Institute (TGen, or TGRI) examined 136 meat samples from 26 grocery stores in Illinois, Florida, California, Arizona and Washington D.C.

Dr. Lance Price, the head researcher on the study, said high levels of Staphylococcus aureus (S.Aureus) bacteria were found in the meat.

"Staph causes hundreds of thousands of infections in the United States every year," Price said in an interview. "It causes a whole slew of infections ranging from skin infections to really bad respiratory infections like pneumonia."

Staph infections also kill more people in the United States each year than HIV, he said.

A spokeswoman for the Food and Drug Administration said that the agency was aware of the TGen findings, and similar studies of antibiotic-resistant bacteria in meats, and was working with the US Agriculture Department and Centers for Disease Control and Prevention on the causes and effects.

"FDA has been monitoring the situation. The TGRI study points out that the public health relevance of the findings is unclear. FDA continues to work with CDC and USDA to better understand this issue," the FDA spokeswoman said.

Price said the most significant findings from the study aren't the level of bacteria they found, but rather how the bacteria in the meat was becoming strongly resistant to antibiotics farmers use to treat the animals they slaughter.

The study found that in 96 percent of the meats with staph bacteria the bacteria were resistant to at least one type of antibiotic, and 52 percent were resistant to three or more types.

"The bacteria is always going to be there. But the reason why they're resistant is directly related to antibiotic use in food animal production," Price said. "Antibiotic resistance is one of the greatest threats to public health we face today."

"This is one more reason to be very careful when you're handling raw meat and poultry in the kitchen," Price said. "You can cook away these bacteria. But the problem is when you bring in that raw product, you almost inevitably contaminate your kitchen with these bacteria."

Washing hands and counters before and after handling meat and keeping other foods away from uncooked meat are ways to prevent disease from spreading, Price said. But consumer initiatives aren't going to solve the bigger problem, he said.

"To put it all on the consumer is really directing blame at the wrong end of the food chain," Price said. "The bacteria is always going to be there, but the reason why they're resistant is directly related to antibiotic use in food animal production."

Of all the types of meats where bacteria was resistant to three or more antibiotics in the study, turkey was the most resistant, followed by pork, beef and then chicken. Price said it's not clear why turkey was the most resistant.