The pathogenesis of infection by Listeria monocytogenes

Area of Science:

• Microbiology
• Pathogen Biology
• Infectious Diseases

Background:

• Listeria monocytogenes is a Gram-positive bacterium causing severe human and animal infections.
• It is a facultative intracellular pathogen that invades macrophages and tissue cells, proliferating within hosts.
• The molecular mechanisms of its intracellular parasitism are largely understood.

Purpose of the Study:

• To elucidate the molecular basis of Listeria monocytogenes' intracellular parasitism.
• To detail the virulence factors and genetic organization responsible for infection.
• To describe the pathogenesis and spread of Listeria monocytogenes within host organisms.

Main Methods:

• Analysis of chromosomal genes encoding virulence factors like internalin, listeriolysin O, phospholipases, and ActA.
• Description of host cell invasion, phagosomal escape, and cytoplasmic entry.
• Explanation of cell-to-cell spread via actin polymerization.

Main Results:

• Listeria monocytogenes utilizes specific virulence factors encoded by operons for intracellular survival and proliferation.
• The bacteria spread from cell to cell using actin polymerization, facilitating systemic infection.
• Infection targets the liver, leading to hepatocyte lysis, prolonged septicemia, and potential spread to the placenta and brain.

Conclusions:

• Listeria monocytogenes employs a sophisticated intracellular parasitic strategy involving specific virulence factors and host cell manipulation.
• The bacterium's ability to spread intracellularly and systemically contributes to severe disease outcomes, including meningoencephalitis.
• Despite treatment, listeriosis remains a significant threat with high mortality, particularly in immunocompromised individuals.