Tracing the Steps of a Deathly Pathogen

Listeria monocytogenes is a deathly, pathogenic bacterium that can cause Listeriosis in humans. Listeriosis is a foodborne disease with a high mortality rate, and birth defects in the cases of pregnant patients. However, recent research has found that this bacterium can replicate in the murine gall bladder, and that its replication is extracellular and intraluminal. These findings were supported by extensive research done on Balb/c mice, by injecting them with two L.monocytogenes strains (10403S and LM23074) that were made luminescent with the help of chromosomal integration of a lux-kan transposon. The mice were either orally or intravenously infected with the L.monocytogenes strains to observe bacterial activity in vivo through bioluminescent images. After dissection, researchers recovered virulent strains only from the murine gall bladder, which prompted them to further investigate luminal contents of the gall bladder. As a result, they found that the bacterium could replicate extracellularly in the lumen of the gall bladder in living mice. This is important because it can lead to more safe treatment options for Listeriosis, specifically for pregnant women.

A.) Infected mouse on day 3. B.) Luminal contents of the gall bladder. C.) Bioluminscent colonies recovered from the infected gall bladder. D.) Tissue Gram stain of an infected gall bladder of a mouse. Image retrieved from article (Hardy et al., 2004).

Hardy J., Francis K.P., DeBoer M., Chu P., Gibbs K. and Contag C.H. (2004). “Extracellular Replication of Listeria Monocytogenes in the Murine Gall Bladder,” Science (New York, N.Y.), 303(5659), pp. 851–3.