Gram positive bacillus.
Exhibits tumbling motility at room temperature.
Easily grown on agar.
Ubiquitous and found in soil, animals and can colonize human gastrointestinal tract without symptoms.
Principal manifestation of infections are meningitis, meningoencephalitis and bacteremia.
Other reported infections include endocarditis, wound infections, pneumonia, ocular infections, gastroenteritis, maternal-neonatal infection and abortions.
Causes approximately 1% of bacterial meningitis in neonates and approximately 5% of bacterial meningitis in patients older than 16 years.
Most patients cases of Listeria monocytogenes bacterial meningitis occur in patients older than 50 years or in those with cellular immuno deficiency.
The gastrointestinal tract is the usual portal of entry.
It is a food borne pathogen associated with consumption of contaminated coleslaw, raw vegetables, milk, cheese, contaminated turkey franks, alfalfa tablets, cantaloupe, diced celery, hog head cheese, and processed meats.
In addition to contaminated food, this theory has been isolated from dust, soil, water, sewage, and decaying vegetable matter.
Listeria is uncommon in areas where regulated food hygiene safety is required.
Monocytogenes meningitis is more common among immunocompromised persons than among immunocompetent persons.
Most cases of listeria meningitis are due to patients receiving biologic therapies such as infliximab or rituximab.
Typically sporadic infections.
The Morbidity and Mortality Weekly Report revealed 1651 cases of the foodborne illness reported between 2009 2011, with 292 deaths or fetal losses.
More than half of the above cases were in adults age 65 years or older, and 14% pregnancy related.
In the above study 74% of patients younger than 65 years and immunocompromise medical condition.
Soft cheeses, contaminated cantaloupe, precut celery and sushi rolls have been implicated In such infections. Food borne infections have been reported.
Responsible for serious illnesses in neonates.
Refrigerated contaminated foods can be a source of infections and include: cheese, cabbage and milk.
Treatment of choice for systemic disease is ampicillin or penicillin G combined with an aminoglycoside.