Listeria - What is Listeria?

Listeria is a bacterial genus containing seven species. Named after the English pioneer of sterile surgery, Joseph Lister, Listeria species are Gram-positive bacilli and are typified by ''L. monocytogenes'', the causative agent of listeriosis.

Listeria ivanovii is a pathogen of ruminants, and can infect mice in the laboratory, although it is only rarely the cause of human disease.

Listeria monocytogenes is a bacterium commonly found in soil, stream water, sewage, plants, and food. Each bacterium is gram-positive and rod-shaped.

Listeria are known to be the bacteria responsible for listeriosis, a rare but potentially lethal food-borne infection: the case fatality rate for those with a severe form of infection may approach 25% (''Salmonella'', in comparison, has a mortality rate estimated at less than 1%).

They are incredibly hardy and able to grow in temperatures ranging from 4°C (39°F), the temperature of a refrigerator, to 37°C (99°F), the body's internal temperature.

The majority of Listeria bacteria are targeted by the immune system before they are able to cause infection. Those that escape the immune system's initial response, however, spread though intracellular mechanisms and are therefore guarded against circulating immune factors (AMI).

Now characterized as the exotoxin listeriolysin O. with the promotion of virulence factor ActA and aids the bacteria's migration to the host cell's outer membrane. Gelsolin, an actin filament severing protein, localizes at the tail of Listeria and accelerates the bacterium's motility. to contact adjacent cells which subsequently engulf the Listeria rocket and the process is repeated, perpetuating the infection.

The prevention of Listeria as a food illness involves effective sanitation of food contact surfaces. Alcohol has proven to be an effective topical sanitizer against Listeria.

Quaternary ammonium can be used in conjunction with alcohol as a food contact safe sanitizer with increased duration of the sanitizing action. Nonflammable Alcohol Vapour in carbon dioxide NAV-CO2 systems or sodium hypochlorite are frequently used to sanitize surfaces to prevent Listeria.

Refrigerated foods in the home should be kept below 4C to discourage bacterial growth. preventing listeria also can be done by carrying out an effecitve sanitation of food contact surfaces.

Listeria is an opportunistic pathogen: it is most prevalent in the elderly, pregnant mothers, and AIDS patients. With improved healthcare leading to a growing elderly population and extended life expectancies for AIDS patients, physicians are more likely to encounter this otherwise rare infection (only 7 per 1,000,000 healthy people are infected with virulent Listeria each year).

Further Reading

This article is licensed under the Creative Commons Attribution-ShareAlike License. It uses material from the Wikipedia article on "Listeria" All material adapted used from Wikipedia is available under the terms of the Creative Commons Attribution-ShareAlike License. Wikipedia® itself is a registered trademark of the Wikimedia Foundation, Inc.

Last Updated: Feb 1, 2011

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