Listeriosis overview
|
Listeriosis Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Listeriosis overview On the Web |
|
American Roentgen Ray Society Images of Listeriosis overview |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Listeriosis is a bacterial infection caused by a gram-positive, motile bacterium, Listeria monocytogenes.[1] Listeriosis is relatively rare and occurs primarily in newborn infants, elderly patients, and patients who are immunocompromised.[2]
Pathophysiology
Most human infections follow consumption of contaminated food. Rare cases of nosocomial transmission have been reported.
When Listeria bacteria get into a food processing factory, they can live there for years, sometimes contaminating food products. The bacterium has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in foods that become contaminated after cooking or processing, such as soft cheeses, processed meats such as hot dogs and deli meat (both products in factory-sealed packages and products sold at deli counters), and smoked seafood. Unpasteurized (raw) milk and cheeses and other foods made from unpasteurized milk are particularly likely to contain the bacterium.
Listeria is killed by pasteurization and cooking; however, in some ready-to-eat foods, such as hot dogs and deli meats, contamination may occur after factory cooking but before packaging. Unlike most bacteria, Listeria can grow and multiply in some foods in the refrigerator.
Causes
According to the U.S. Centers for Disease Control and Prevention, listeriosis is an important public health problem in the United States.The bacteria (L. monocytogenes) that cause this disease are common in wild animals, domesticated animals, and in soil and water. The bacteria make many animals sick and commonly lead to miscarriage and stillbirth in domestic animals.
Diagnosis
Laboratory Findings
Diagnosis is confirmed only after isolation of Listeria monocytogenes from a normally sterile site, such as blood, or from amniotic fluid or the placenta in the setting of pregnancy. Listeria monocytogenes can be isolated readily on routine media, but care must be taken to distinguish this organism from other Gram-positive rods, particularly diphtheroids. Selective enrichment media improve rates of isolation from contaminated specimens. Serological tests are unreliable, and not recommended at the present time.
Treatment
Medical Therapy
Bacteremia should be treated for 2 weeks, meningitis for 3 weeks, and brain abscess for at least 6 weeks. Ampicillin generally is considered antibiotic of choice; gentamicin is added frequently for its synergistic effects. Overall mortality rate is 20-30%; of all pregnancy-related cases, 22% resulted in fetal loss or neonatal death, but mothers usually survive.
Prevention
The prevention of Listeria as a food illness involves effective sanitizing of food contact surfaces. Alcohol has proven to be an effective topical sanitizer against Listeria. Quaternary ammonium 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.
References
- ↑ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9.
- ↑ Hof H (1996). Listeria Monocytogenes in: Baron's Medical Microbiology (Baron S et al, eds.) (4th ed. ed.). Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.