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Health Dictionary

Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.

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Listeria

Introduction

This page is about microbiologic aspects of the organism(s).  For clinical aspects of the disease, see Listeriosis.
Overview

Overview

Listeriosis is caused by the bacterium Listeria monocytogenes, a flagellated, catalase-positive, facultative intracellular, anaerobic, nonsporulating, Gram-positive bacillus. Listeria is commonly found in soil, water, vegetation and fecal material.[1]

Cause

Cause

  • Listeriosis is caused by the bacterium Listeria spp.
  • Listeria monocytogenes is the most common species associated with development of listeriosis.
  • The genus Listeria contains ten species:
  • L. fleischmannii
  • L. grayi
  • L. innocua
  • L. ivanovii
  • L. marthii
  • L. monocytogenes
  • L. rocourtiae
  • L. seeligeri
  • L. weihenstephanensis
  • L. welshimeri
  • Of note, Listeria dinitrificans was previously thought to be part of the Listeria genus, but it has been reclassified into the new genus Jonesia.[2]
Taxonomy

Taxonomy

Bacteria; Firmicutes; Bacilli; Bacillales; Listeriaceae; Listeria; Listeria monocytogenes.

Microbiological Characteristics

Microbiological Characteristics

Natural Reservoir

Natural Reservoir

  • In the environment, Listeria monocytogenes is commonly found in soil, water, vegetation and fecal material.
  • Animals may be asymptomatic carriers of Listeria.[1]
  • L. monocytogenes has been associated with foods such as raw milk, pasteurized fluid milk, cheeses (particularly soft-ripened varieties), ice cream, raw vegetables, fermented raw-meat sausages, raw and cooked poultry, raw meats, and raw and smoked fish.[3]
  • Listeria has the ability to grow at temperatures as low as 0°C, allows its multiplication in refrigerated foods. At refrigerated temperature such as 4°C, the amount of ferric iron in the environment promotes the growth of L. monocytogenes.[4]
Gallery
Electron micrograph of a Listeria bacterium in tissue.Adapted from Public Health Image Library (PHIL), Centers for Disease Control and Prevention.[5]
Electron micrograph of a Listeria bacterium in tissue.Adapted from Public Health Image Library (PHIL), Centers for Disease Control and Prevention.[5]
References

References

  1. ↑ 1.0 1.1 “Risk assessment of Listeria monocytogenes in ready-to-eat foods” (PDF).
  2. ↑ M. D. Collins, S. Wallbanks, D. J. Lane, J. Shah, R. Nietupskin, J. Smida, M. Dorsch and E. Stackebrandt. Phylogenetic Analysis of the Genus Listeria Based on Reverse Transcriptase Sequencing of 16S rRNA. International Journal of Systematic and Evolutionary Microbiology. April 1991 vol. 41 no. 2 240–246
  3. ↑ Fleming, D. W., S. L. Cochi, K. L. MacDonald, J. Brondum, P. S. Hayes, B. D. Plikaytis, M. B. Holmes, A. Audurier, C. V. Broome, and A. L. Reingold. 1985. Pasteurized milk as a vehicle of infection in an outbreak of listeriosis. N. Engl. J. Med. 312:404-407.
  4. ↑ Dykes, G. A., Dworaczek (Kubo), M. 2002. Influence of interactions between temperature, ferric ammonium citrate and glycine betaine on the growth of Listeria monocytogenes in a defined medium. Lett Appl Microbiol. 35(6):538-42.
  5. ↑ 5.0 5.1 “Public Health Image Library (PHIL), Centers for Disease Control and Prevention”.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]