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
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.
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).
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Last Updated: Feb 1, 2011