CBS Local — Hospitals are known for their strict rules on cleanliness and sterile environments. A new report is shining a troubling light on one source of contamination inside medical facilities: the nurses and their scrubs.

Researchers at Duke University Hospital say that they studied the amount of bacterial contamination on nurses’ clothing during their work shifts. Of the 40 nurses the study followed, new bacteria was found on their scrubs 19 times out of 120 shifts tested.

“There is no such thing as a sterile environment,” said lead author Dr. Deverick Anderson. “Bacteria and pathogens will always be in the environment. Hospitals need to create and use protocols for improved cleaning of the healthcare environment,” the director of the Center for Antimicrobial Stewardship and Infection Prevention added.

The most common type of bacteria found on the scrubs was Staphylococcus aureus, which includes MRSA; the antibiotic-resistant super bug that causes infections all over the body. The study reportedly also looked into changing the materials nurses used for their scrubs, but it didn’t result in any change in the rate of contamination.

“Patients and family members should feel empowered to ask healthcare providers if they are doing everything they can to keep their loved one from being exposed to bacteria in the environment,” Dr. Anderson added. The amount of bacteria possibly being carried from room to room is even more alarming when combined with the current rate of hospital infections recorded each year. According to the CDC, one in every 25 hospital patients contracts a healthcare-associated infection.