Listeria monocytogenes has long been one of the most fearsome foodborne pathogens. With a high mortality rate and the ability to grow at refrigerator temperatures, it’s also one of the most adaptable. Now, researchers in Denmark say they’ve made some important discoveries that explain why the bug is difficult to fight, according to Medical News Today. In the study, published in Nucleic Acids Research, researchers hit Listeria colonies with a variety of substances to see how the bacteria react. Those substances included antibiotics, bile and ethanol. Listeria stealthily infects host cells by producing too few proteins to be detected by the host’s immune system. When confronted by the various substances, Listeria begins producing special RNA molecules that regulate protein production. The bacteria are also able to rapidly repair their cell walls in the presence of antibiotics. The study also found that Listeria only produces RNA molecules when in the presence of a challenging substance. Overall, the study sheds some more insight on Listeria’s adaptability. The next step: Determining whether removing the RNA molecules would be an effective strategy for treatment of Listeria infections. Each year, approximately 1,600 Americans fall ill with Listeria infections and 260 die, according to the U.S. Centers for Disease Control and Prevention. A recent Listeria outbreak in Denmark linked to sausage products sickened at least 28 people and killed 12. Listeria is most commonly associated with ready-to-eat deli meats, hot dogs, meat spreads, raw milk, smoked seafood and raw sprouts. Pregnant women are largely discouraged from eating such foods because Listeria infections can often lead to miscarriage or stillbirth. In 2011, Listeria in cantaloupe sickened more than 140 Americans and killed more than three dozen, becoming one of the deadliest foodborne illness outbreaks in U.S. history.
