Sanitizer-Resilient Deadly Bacteria Detected in Food, Posing Health Risks

"Scientists at Penn State University have discovered that Listeria bacteria may evade sanitizers by forming protective biofilms with other bacteria in fruit-packing environments, raising concerns about the effectiveness of current sanitation protocols. The Centers for Disease Control and Prevention reports Listeria as the third leading cause of death from foodborne diseases in the U.S., with approximately 1,600 serious infections annually. The study suggests that the biofilm acts as a physical barrier, reducing the impact of sanitizers, potentially increasing Listeria's tolerance. Findings underscore the need to reassess and enhance sanitation protocols in food processing to control Listeria monocytogenes effectively."


Worldsfeed Health Desk: The efficacy of current measures to protect against potentially lethal bacteria, such as Listeria, is being questioned by scientists who warn that these efforts may prove inadequate. Listeria ranks as the third leading cause of death from foodborne diseases in the United States, with the Centers for Disease Control and Prevention reporting around 1,600 serious infections annually, resulting in approximately 260 deaths. Despite the typically mild nature of the illness, the ability of Listeria bacteria to extend beyond the intestines poses a significant health threat.

In an attempt to prevent Listeria contamination, food suppliers commonly employ sanitizers on their produce. However, a recent study conducted by Penn State University reveals a concerning possibility – Listeria bacteria may have the ability to evade these sanitation protocols. The study, published in the journal Biofilm, sheds light on how other seemingly harmless species of bacteria in the fruit-packing environment can collaborate to form a protective shield, known as a biofilm, around the Listeria bacteria.

Co-author Jasna Kovac, a Professor of Food Safety at Penn State, explained, “We found two groups of microorganisms in the tree fruit packing environments, Pseudomonadaceae and Xanthomonadaceae, that are very good at forming biofilms and protecting Listeria monocytogenes.” This biofilm acts as a physical barrier, reducing the effective diffusion and antimicrobial action of sanitizers. The protected Listeria bacteria, therefore, face a lower dose of sanitizer, making them more tolerant.

The study underscores the necessity to evaluate the effectiveness of commonly used sanitizers against the seemingly harmless biofilm-forming bacteria prevalent in food processing environments. Co-author Luke LaBorde, a professor in food science and an expert in tracking Listeria monocytogenes in produce production and processing environments, stated, “The findings of this research project will inform and enhance sanitation protocols and extension training efforts targeted at the tree-fruit industry to effectively control Listeria monocytogenes.”

For individuals at higher risk, including the immunocompromised, pregnant women, and those over the age of 65, the CDC recommends avoiding certain foods more likely to contain Listeria. These include unpasteurized soft cheese – with alternatives like harder cheese, cream cheese, or pasteurized soft cheese suggested. Similarly, opting for reheated deli meats rather than unheated ones, choosing freshly cut melon over that left out for extended periods, and selecting sprouts that have been cooked until steaming hot are recommended precautions.

In conclusion, the study’s findings raise important questions about the adequacy of current sanitation protocols against Listeria, urging a reevaluation of practices to better control the bacteria in food processing environments.

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