The army of microbes that resides in the human gut may provide a powerful defense against Listeria infection, according to a study published in mBio, the online open-access journal of the American Society for Microbiology. The study, by a team of French researchers, shows that mice with germ-free intestines are more susceptible to Listeria infection than mice with the conventional intestinal microbes.
Twenty four hours after infection, the number of Listeria in the intestines of the germ-free mice was 10,000 times greater than the number found in the small intestines of mice with conventional microbes; and about 1,000 times higher in the mesenteric lymph nodes of germ-free mice than it was in conventional mice. Researchers think the response may be similar in humans.
Foods contaminated with Listeria sicken about 800 people every year in the U.S. About 95 percent of listeriosis cases require hospitalization and about 20 percent are fatal. Seniors, pregnant women and those with compromised immuned systems are most susceptible.
Some foods carry a higher risk of Listeria than others. To reduce exposure to Listeria, the Centers for Disease Control and Prevention (CDC) recommends avoiding consumption of raw dairy products, unpasteurized juices, soft cheeses, smoked seafood, raw sprouts, and deli meats or hot dogs that have not been heated before eating. Take care to wash all raw produce thoroughly and prevent cross-contamination in the kitchen by not re-using knives and cutting boards used to prepare raw produce until they have been washed in hot soapy water. And always cook foods to a safe final internal temperature, as measured with a reliable food thermometer.
