The bacterium which has always been a matter of concern for the government and the food and Agricultural industry, Listeria monocytogenes, is the causative agent of Listeriosis.
Eating food contaminated with L. monocytogenes, usually the ready-to-eat foods including seafood’s, vegetables, fruits, dairy products and meat, can result in Listeriosis, an uncommon but potentially fatal disease. In today’s fast life we eat such type of refrigerated food everyday. This fact calls for the necessity to know about this organism.
The majority of Listeriosis cases occur among pregnant women, the elderly, and persons with weakened immune systems such as those suffering from AIDS, Diabetes or Cancer. Illness in pregnant women can result in miscarriage, stillbirth, or severe illness leads to death of a newborn infant.
The organism is found the GI tract of warm blooded animals. It adheres to the cells by means of D-Galactose residues on its surface and the D-Galactose receptors on the epithelial surface. Induced phagocytosis with the help of membrane bound protein Internalin, leads to the entry of this bacterium into the cell. Inside the cell it forms listeriolysin which protects it from the phagosome and also eventually causes the lysis of phagosome and release of the bacteria. Polymerizing of the actin in the cell by these bacteria develops large filaments which serve as tails for L. monocytogenes. The bacterium move from cell to cell with the help of these tails.
Thus replication in cytoplasm and invading other adjacent cells ultimately leads to infection.
Listeriosis begins often with influenza-like symptoms, and sometimes with diarrhea, which might occur within 1 week after eating contaminated food. Symptoms might progress to include high fever, severe headache, and neck stiffness, convulsions and sometimes even meningitis causing death.
An incidence of around four cases per million populations was quoted in the UK, and an overall annual incidence in the USA of 7.1 cases per million populations.Public health scientists have always had an interest in prevention of food contamination for a hundred years and more.
The major preventive measures include using only pasteurized dairy products, eating only thoroughly cooked or reheated meat, poultry or seafood, washing all fruits and vegetables with water before eating and following the label instructions on products that must be refrigerated or that have a "use by" date.
The infection can be detected by serum culture under routine investigation in pregnancy or after arrival of symptoms in other individuals. It is treated with penicillin or ampicillin or with both together with amino glycosides.The US Department of Agriculture and the Food Safety and Inspection Service have published ways to prevent the infection by Listeria.
If these instructions are followed strictly, Listeriosis would be wiped out completely and this would in turn yield to dramatic public health benefits.
References:
1) Bergey’s Manual, Volume: 1
2) Todar’s online Textbook of Bacteriology
3) http://biology.kenyon.edu/Microbial_Biorealm/bacteria/gram-positive/listeria/listeria.htm#classif
4) http://www.med.ufl.edu/biochem/dlpurich/ACTPRIM.htm
5) Food Microbiology
6) http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/actin.htm
7) http://www.cdc.gov/ncidod/dbmd/diseaseinfo/listeriosis_g.htm
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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