Listeria monocytogenes is a Gram-positive, motile, intracellular facultative anaerobe that inhabits a broad ecological niche. It is the aetiological agent of listeriosis, a rare but extremely severe systemic infection in humans.

Our current understanding of the epidemiology of human listeriosis would suggest that the organism is a common contaminant of food products, with as much as 15% of food contaminated. Once contaminated food has been ingested, invasion may take place at sites in the nasopharynx or the upper part of the alimentary tract. A wide variety of clinical syndromes have been associated with L. monocytogenes infection in both humans and animals due to the organism being an opportunistic pathogen with the ability to invade cells in vivo. Listeriosis is characterised by meningitis, septicaemia and foetal death and the current rate of infection in England and Wales is estimated to be around 150 cases per year.

Treatment. Treatment of listeriosis is usually by a combination of amoxycillin and gentamycin, however attempts at aiming to exclude all L.monocytogenes from the food chain are likely to contribute to the prevention of this disease.

Kindly provided by David Pearce, School of Biological Sciences University of Manchester