LISTERIOSIS OUTBREAK

Listeriosis Outbreak Caused by Contaminated Cantaloupes

Listeriosis Outbreak Caused by Contaminated Cantaloupes

Introduction

A foodborne disease outbreak is defined as the event that two or more people contract by the same contaminated food or drink. Public health officials investigate outbreaks to control them and prevent more people becoming ill during the outbreak, and to know how to prevent similar outbreaks occur in the future. The paper discusses the recent foodborne listeriosis outbreak due to contaminated cantaloupes in the United States of America. It details out the infectious organism involved and determine how the infection spread across several states of United States.

Name of the organism involved

Listeriosis monocytogenes is a bacterium that develops intracellular causing listeriosis. It is one of the pathogens causing food-borne infections which are more virulent, with a mortality rate between 20 to 30%, higher than almost all other food intoxications. Listeria infections represent a significant risk for pregnant women, which may not have obvious symptoms. The fetus can become infected before birth, causing abortion from the second month of pregnancy, although most commonly in the fifth and sixth month. Infection later in pregnancy may result in exposure during childbirth, sometimes leading to the infection of the newborn, which can be fatal. L. monocytogenes is a bacillus Gram positive, named after the English surgeon Joseph Lister. it is a small (0.4 to 0.5 microns wide x 0.5 to 1.2 long) unbranched and facultative anaerobe able to grow over a wide range of temperatures (1 ° C to 45 ° C) and high salt concentration. It is catalase positive and has no capsule or spore. It has flagella peritrichous, through which it presents mobility at 30 ° C or less but is still at 37 ° C, temperature at which their flagella are inactivated (FDA, 2011).

2. Main Traits of the Organism

L. monocytogenes is a facultative intracellular pathogen that can grow in macrophages, the epithelial cells and fibroblasts in suitable environment. After the ingestion of contaminated food, L. monocytogenes can survive exposure to proteolytic enzymes, gastric acid and bile salts. Mainly, it contains a protein called internalin , which interacts with the cell receptor for host cell adhesion, this is called E-cadherin which induces phagocytosis, these being specific to each tissue. The presence of internalinas facilitates entry of the microorganism cells. The body reacts by creating a sort of phagosome to encapsulate the bacteria but this produces listeriolysin O and phospholipases C that allows the bacteria to destroy the phagosome hydrolyzing the lipid membrane (FDA, 2011).

This listeriolysin is encoded by the gene hly. Being in the cytosol L. monocytogenes utilizes a surface protein called ActA which generates the intracellular actin polymerization.

These filaments are rearranged in a long tail which extends from one end of the bacterium. By the movement of the queue, the microorganism migrates through the cytoplasm into the host cell membrane. On the periphery, they form protrusions (phyllopod) that can penetrate adjacent cells and allow the entry of the bacteria ...