A concerned member of the StateFoodSafety.com team recently asked a pertinent food safety question that has crossed my mind as well. Just how long can bacteria such as E. coli, Shigella, and Salmonella survive on inanimate surfaces?
According to a 2006 study, these particular species can persist for months on dry surfaces. In addition, these pathogens thrive longer in humid environments and low temperatures. Researchers reached conflicting conclusions about the effects of surface types on the life span of the bacteria. Some insisted that the species persisted longer on plastic, while others found “a survival advantage on steel.” Nevertheless, the study, which was primarily focusing on the transmission of bacteria and viruses in hospitals, has significant implications for the food service industry as well.
For example, the study’s conclusion emphasizes the importance of cleaning and sanitizing hard surfaces to minimize the presence of harmful bacteria. All food workers should be aware of this vital step when cleaning food preparation and dining areas. In addition, proper hand washing is crucial in preventing infection from or transmission of these long-living pathogens. Food preparation workers, like medical personnel, should also wear disposable gloves as a precautionary measure. Because of the potentially long survival rate of harmful bacteria on surfaces, never assume that if you leave a surface long enough, it will cease to be a threat.
Furthermore, because harmful bacteria can persist on surfaces for extended periods of time, you should also probably reconsider your faithful adherence to the “Five-Second Rule”—the one that makes eating food within five seconds of dropping it on the floor perfectly acceptable. A Clemson study from 2003 confirms that salmonella could survive on a surface for months. After contaminating a surface with Salmonella eight hours previously, researchers dropped slices of bread and bologna, left them sitting for a mere five seconds, and found that the food slices had 150 to 8,000 bacteria on them. Even as few as 10 Salmonellas can cause illness. Thus, the moral of the story is that surfaces can potentially contain harmful microbes that can persist for months and even brief contact with such surfaces can result in negative consequences. Clean surfaces often and don’t eat food off the floor. It sounds silly, but we’re all guilty of ignoring these simple guidelines.