display | more...
Listeria is a bacterium which is not capable of forming endospores. Only two species are of human pathogenic significance: L. monocytogenes and L. ivanovii. L. monocytogenes have been implicated in several food poisoning epidemics. It lives in the gastrointestinal tract and in animal feces. People who are infected suffered from vomiting, nausea, and diarrhea. Newborns, pregnant women and their fetuses, the elderly, and persons lacking a healthy immune system are the most susceptible. It also causes listeriosis which is an inflammation of the brain. Antibiotics are used for treatment of infection because most strains of Listeria are sensitive to ampicillin and gentamicin.

Hard data from medic.med.uth.tmc.edu

As mentioned in a previous writeup, Listeria is a type of bacteria associated with food poisoning epidemics. What is particularly interesting about listeria, however, is how it affects one's cells.

There is a ActA protein on its surface that sticks to and activates actin regulating complex Arp2/3. These, now active, actin regulators nucleate the polymerization of actin microfilaments which trail behind the bacteria like a comet's tail as it is propelled across the cytoplasm and into the cell wall. Eventually the bacterial causes the cell wall to bulge and finally release the bacteria into a neighboring cell. Thus, the bacteria never has to enter the intracellular space where it might get attacked by the immune system. Bacteria called Shigella and Rickettsiae behave in a similar manner.

The other key part of the pathogenicity of L. monocytogenes is the gene LLO, which produces the protein Listeriolysin O.

This protein let's the bacterium escape death after being engulfed by macrophages through the process of phagocytosis. Listeriolysin O breaks up the phagosome after the bacterium is internalized, allowing its escape into the cytoplasm.

Bacteria and viruses are sneaky bastards.

Log in or register to write something here or to contact authors.