Last updated: January 25, 2022

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Listeriosis is an infectious disease caused by the gram-positive bacterium Listeria monocytogenes. The bacteria are usually transmitted to humans through ingestion of contaminated food (especially raw milk products). In immunocompetent patients, the disease is mostly asymptomatic, although mild flu-like symptoms or febrile gastroenteritis may occur. Invasive disease due to bacteria spreading beyond the gastrointestinal tract results in most symptoms and generally develops in high-risk groups, including immunocompromised, elderly, and pregnant patients. The clinical manifestation is usually mild in pregnant women, but consequences for the fetus can be very severe (see congenital listeriosis). In immunocompromised and elderly patients, invasive disease can lead to sepsis and meningitis. Suspected listeriosis can be differentiated from other causes of infection through blood cultures. Antibiotic therapy is indicated for high-risk groups; ampicillin or penicillin G are the drugs of choice.

  • Pathogen: Listeria monocytogenes; a gram-positive, catalase-positive, rod-shaped, facultative intracellular, motile bacterium
  • Route of transmission
    • Acquired listeriosis: ingestion of contaminated food (listeria can grow in temperatures as low as -1.5 ºC) [1]
      • Raw milk products
      • Raw and smoked meat/fish
      • Industrially processed vegetables such as ready-made salads
    • Congenital listeriosis [2]
      • Transplacental transmission during pregnancy
      • Perinatal transmission (via infected vaginal secretions)
  • Incubation time:1–90 days (usually within a month) [3]
  • Risk factors

Most infections are asymptomatic or mild, especially in immunocompetent individuals. [6]

Testing is generally not needed in immunocompetent individuals, as the infection is self-limiting and symptoms will have resolved by the time listeriosis is diagnosed.

  • High-risk individuals should avoid food products made from unpasteurized milk and soft cheeses (e.g., brie, feta, and camembert).
  • Properly cook meat prior to consumption
  • Listeriosis is a notifiable disease in the United States.
  1. Pizarro-Cerda J, Kuhbacher A, Cossart P. Entry of Listeria monocytogenes in Mammalian Epithelial Cells: An Updated View. Cold Spring Harbor Perspectives in Medicine. 2012; 2 (11): p.a010009-a010009. doi: 10.1101/cshperspect.a010009 . | Open in Read by QxMD
  2. Dussurget O, Bierne H, Cossart P. The bacterial pathogen Listeria monocytogenes and the interferon family: type I, type II and type III interferons. Frontiers in Cellular and Infection Microbiology. 2014; 4 . doi: 10.3389/fcimb.2014.00050 . | Open in Read by QxMD
  3. Listeria . . Accessed: October 23, 2016.
  4. Vázquez-Boland JA, Krypotou E, Scortti M. Listeria Placental Infection. mBio. 2017; 8 (3). doi: 10.1128/mbio.00949-17 . | Open in Read by QxMD
  5. What is the incubation period for listeriosis?. Updated: January 10, 2013. Accessed: October 23, 2016.
  6. Lorber B.. Listeriosis. undefined. 1997; 24 : p.1-9.
  7. Castellazzi ML, Marchisio P, Bosis S. Listeria monocytogenes meningitis in immunocompetent and healthy children: a case report and a review of the literature. Italian Journal of Pediatrics. 2018; 44 (1). doi: 10.1186/s13052-018-0595-5 . | Open in Read by QxMD
  8. Zach T. Listeria Infection Clinical Presentation. In: Steele RW, Listeria Infection Clinical Presentation. New York, NY: WebMD. Updated: October 20, 2015. Accessed: October 23, 2016.
  9. Gelfand MS. Clinical manifestations and diagnosis of Listeria monocytogenes infection. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. updated: November 23, 2015. Accessed: October 23, 2016.
  10. Gelfand MS. Treatment, prognosis, and prevention of Listeria monocytogenes infection. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. updated: July 27, 2016. Accessed: October 23, 2016.
  11. Gelfand MS. Clinical manifestations and diagnosis of Listeria monocytogenes infection. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. updated: November 16, 2016. Accessed: March 22, 2017.

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