Why this common soil bacterium thrives in your refrigerator and threatens human health

Gardening · Published 3 October 2026 Swipe more like this →

In short: Listeria monocytogenes is a resilient pathogen that defies standard food safety expectations by multiplying at refrigeration temperatures. While often harmless to healthy individuals, this soil-dwelling bacterium can trigger severe, life-threatening infections in vulnerable groups, including pregnant women, newborns, and those with compromised immune systems, making it a critical food safety concern.

First described in 1926 by E.G.D. Murray after observing sudden deaths in rabbits, Listeria monocytogenes was initially identified as a veterinary concern. It was not until an outbreak in Canada in 1981, linked to contaminated coleslaw, that its role as a significant foodborne pathogen was fully recognized. Today, it is understood to be a ubiquitous organism found in soil, water, sewage, and decaying vegetation, allowing it to easily enter food production environments.

The bacterium's survival strategy is uniquely dangerous. Unlike many pathogens that are halted by cold, Listeria can grow and reproduce at typical refrigeration temperatures. Once ingested, it demonstrates a sophisticated ability to invade host cells. It uses specialized proteins called internalins to enter epithelial cells and then employs an actin-based motility system—often described as 'comet tails'—to propel itself through the host's cytoplasm and spread to neighboring cells. This intracellular lifestyle allows it to bypass the immune system, leading to invasive listeriosis.

Invasive listeriosis occurs when the bacteria spread beyond the intestines, potentially causing meningitis, sepsis, and severe pregnancy complications like miscarriage or stillbirth. While most healthy people experience only mild, short-lived gastrointestinal symptoms, the risk is acute for those over 65, transplant recipients, and individuals with conditions like cancer or HIV. Because the pathogen can survive in ready-to-eat foods like deli meats, soft cheeses, and smoked fish, public health guidance emphasizes strict temperature control and the avoidance of high-risk foods for vulnerable populations.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

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