Today's Friday beautiful science comes from the lab of Julie Theriot. These are sped up movies of Listeria bacteria inside human cells. Listeria actually attaches to the actin filaments inside the cell, and uses the actin to force itself around through the cell (and to force its way into neighboring cells). On the left side of the human cell, you can see some bacteria stretching the cytoplasm. If there had been another human cell adjacent to this one, the Listeria cell likely would have punctured the membrane of the human cell, and moved directly into the adjacent human cell. Super cool.
From the Theriot lab website:
Listeria monocytogenes is a small rod shaped gram-positive bacterium that is ubiquitous in the environment, in the soil, on plants and animals. Listeriosis (the state of Listeria infection) is associated with eating of unpasteurized cheese or dairy products, or consumption of contaminated vegetables. Infection occurs primarily in newborns and infants, elderly or immunocompromised individuals, or pregnant women (mother is asymptomatic or has influenza-like syndrome, but the newborn can acquire it during birth, or infection can cause abortion or premature delivery). According to the CDC about 1500 cases are reported in the United States each year, mostly in the aforementioned high risk groups.Check out this part of Dr. Theriot's site for more cool movies.
Listeria enters the host along with infected food. Most of the bacteria will be killed by acid in the stomach, but the surviving bacteria invade the cells of the intestinal tract, going from cell to cell and thereby spreading the infection laterally. Intracellular movement of the bacteria is essential for this lateral infection to occur, and Listeria has been described to move with a "comet-tail" or like an "actin rocket". The Theriot Laboratory is studying how Listeria moves within cells, and results of this research may someday be used to generate vaccines or other means to prevent infection by Listeria. Currently, the only preventive measures are thorough cooking and cleaning of food, as well as pasteurization of dairy products. Treatment of Listeriosis primarly depends on antibiotics.