Liseria: Lifecycle

“During entry, the invasion protein InlA takes advantage of the adhesion molecule E-cadherin and the adherens junction machinery to adhere to target and invade polarized epithelial cells. Another invasion protein of the internalin family, InlB, subverts the signalling pathway of the hepatocyte growth factor receptor Met to induce endocytosis of the receptor and also to favour internalization of the bacteria in non-polarized epithelial cells. Once inside the cell, the haemolysin of L. monocytogenes–the listeriolysin O or LLO–is secreted to lyse the phagocytic vacuole, and when the bacteria is freed in the cytoplasm, the activity of the LLO is in part regulated by the infected cell itself, taking advantage of the pH sensitivity of the LLO that leads to its inactivation in the neutral eukaryotic cell cytoplasm. Finally, to induce bacterial movement in the cytoplasm, the L. monocytogenes surface protein ActA mimics the activity of the eukaryotic WASP family of proteins to recruit to the bacteria the actin nucleation machinery required for actin polymerization and for the formation of the actin structures (called ‘actin comet tails’) that propel the parasite in the cytosol and help it to invade neighbouring cells.”

References:

Picture: http://www.nature.com/nrmicro/journal/v4/n6/images/nrmicro1413-f1.jpg

Subversion of cellular functions by Listeria monocytogenes. [J Pathol. 2006] – PubMed – NCBI. (n.d.). National Center for Biotechnology Information. Retrieved April 18, 2013, from http://www.ncbi.nlm.nih.gov/pubmed/16362984

Listeria: Movement

“Listeria uses the cellular machinery to move around inside the host cell: It induces directed polymerization of actin by the ActA transmembrane protein, thus pushing the bacterial cell around”

“Listeria must then navigate to the cell’s periphery to spread the infection to other cells. Outside the body, Listeria has flagellar-driven motility, sometimes described as a “tumbling motility”. However, at 37 °C, flagella cease to develop and the bacterium instead usurps the host cell’s cytoskeleton to move. Listeria, inventively, polymerizes an actin tail.

Once at the cell surface, the actin-propelled Listeria pushes against the cell’s membrane to form protrusions called filopods”

References

How the Listeria monocytogenes ActA protein converts actin polymerization into a motile force. [Trends Microbiol. 1997] – PubMed – NCBI. (n.d.). National Center for Biotechnology Information. Retrieved April 18, 2013, from http://www.ncbi.nlm.nih.gov/pubmed/9234509

Encephalitis., & infections., a. p. (n.d.). Listeria. Online Textbook of Bacteriology. Retrieved April 18, 2013, from http://textbookofbacteriology.net/Listeria.html

Listeria: Nutrition

One of the most interesting things about Listeria is that it can survive with almost nothing to eat.

“One of the presumptions is that they’re living on some of the breakdown products of the cells in the population that die. That’s supported by the results that the cells sitting in the original waste material survive better than do those which have their buffer changed every four days.”

A study done on Listeria found that even after 28 days, there was quite a large amount of cells still living because they used the dead cell’s waste. Additionally, the cells go into a stage of dormancy, allowing them be in a state without growth or development. Furthermore, being dormant allows the cell to reduce its metabolizing, minimizing its energy usage.

References:

How does Listeria monocytogenes survive with nothing to live on?. (n.d.). THE MEDICAL NEWS | from News-Medical.Net – Latest Medical News and Research from Around the World. Retrieved April 18, 2013, from http://www.news-medical.net/news/2007/08/29/29219.aspx

Listeria: Habitat

Listeria can survive in a variety of locations. A common location it is found is in soil, where it can spread to crops and animals.

“Listeria has been found in hot dogs, deli meats, pasteurized or unpasteurized milk, cheeses (particularly soft-ripened cheeses like feta, Brie, Camembert, blue-veined, or Mexican-style queso blanco), raw and cooked poultry, raw meats, ice cream, raw vegetables, and raw and smoked fish”

Although cooking or pasteurizing will kill off Listeria, food can still be contaminated with this bacteria before packaging, thus workers must follow strict sanitation guidelines to prevent it.

References:

Picture: http://www.nature.com/nrmicro/journal/v7/n9/images/nrmicro2171-f1.jpg

Listeria monocytogenes in multiple habitats and host populations [Foodborne Pathog Dis. 2006] – PubMed – NCBI. (n.d.). National Center for Biotechnology Information. Retrieved April 18, 2013, from http://www.ncbi.nlm.nih.gov/pubmed/17199514

Listeria: Relationship with humans

What is Listeria?

Listeria is a bacteria that can cause a food borne disease called Listeriosis

How does some one get infected with Listeriosis?

Infection of Listeria occurs when one eats food that is contaminated with Listeria

Who does Listeriosis affect the most?

Listeriosis affects mainly people with a weakened immune system.

“The overt form of the disease has a mortality greater than 25%”

“Salmonella, in comparison, has a mortality rate estimated at less than 1%”

• pregnant women
• newborns
• adults with weakened immune systems
• elderly

General symptoms

• cramps
• diarrhea
• headache
• mild flu-like illness (e.g., chills, fatigue, muscle and joint pain)
• nausea
• persistent fever
• vomiting

Effects during pregnancy

• If the mother is infected before the first 3 months of the pregnancy, there is a chance of miscarriage
• If the mother is infected after the first 3 months, the baby may experience
  • acute illness
  • premature birth
  • stillbirth
  • low birth weight
  • meningitis

   

References:

Listeriosis – Causes, Symptoms, Treatment, Diagnosis – Infection – Body & Health. (n.d.). Site Map – Body & Health. Retrieved April 18, 2013, from http://bodyandhealth.canada.com/channel_condition_info_details.asp?channel_id=1020&disease_id=346&relation_id=70907

Salmonella Food Poisoning – Symptoms, Causes, Treatments – Better Medicine. (n.d.). Local Health – Health and Medical Information You Can Trust – LocalHealth.com – Better Medicine. Retrieved April 18, 2013, from http://www.localhealth.com/article/salmonella-food-poisoning

Encephalitis., & infections., a. p. (n.d.). Listeria. Online Textbook of Bacteriology. Retrieved April 18, 2013, from http://textbookofbacteriology.net/Listeria.html

Listeria: Taxonomy

Kingdom:          Bacteria

Division:            Firmicutes

Class:                   Bacilli

Order:                  Bacillales

Family:                Listeriaceae

Genus:                  Listeria

Species:                L. welshimeri

L. grayi

L. innocua

L. ivanovii

L. monocytogenes

L. seeligeri

L. murrayi