Listeria monocytogenes is a harmful bacterium that causes the foodborne illness listeriosis. This pathogen thrives in moist environments and can contaminate food during growth, harvesting, processing, or storage.
The bacterium enters the body through consumption of contaminated food. Once ingested, Listeria can cross the intestinal lining and spread to other organs, including the brain and placenta in pregnant women. Its ability to grow at refrigeration temperatures makes it particularly dangerous.
Listeria monocytogenes is commonly found in:
The bacterium has multiple serotypes, but only a few are associated with human illness. Serotype 4b is the most common cause of outbreaks in the U.S.
Certain groups are at higher risk, including pregnant women, newborns, elderly adults, and immunocompromised individuals. To prevent infection, follow these guidelines:
| Food Type | Safe Handling Practices |
|---|---|
| Deli meats | Heat until steaming hot |
| Cheese | Choose pasteurized varieties |
| Vegetables | Wash thoroughly |
| Leftovers | Reheat until piping hot |
Proper food storage and handling are important. The CDC recommends cooking foods to safe temperatures and avoiding cross-contamination.
Many people believe that freezing kills Listeria, but the bacterium can survive freezing temperatures. Another myth is that only raw foods pose a risk, but ready-to-eat foods are often the source of contamination. Proper cooking and handling remain the best defenses.