How is Listeria infection (listeriosis) transmitted?

Updated: Jan 09, 2018
  • Author: Terence Zach, MD; Chief Editor: Russell W Steele, MD  more...
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L monocytogenes is a gram-positive, motile, rod-shaped bacterium that is ubiquitous in the environment. L monocytogenes can be isolated in soil, wood, and decaying matter in the natural environment; however, the principal route of acquisition of Listeria is through the ingestion of contaminated food products. Listeria has been isolated from prepared meat (eg, hot dogs, deli meat), dairy products, unwashed raw vegetables, and seafood. Soft cheeses and unpasteurized milk have been the most frequently incriminated dairy products. [4, 5, 6, 7, 8, 9, 10]

Ingestion of Listeria by pregnant women can result in nausea, vomiting, diarrhea, fever, malaise, back pain, and headache. [11] Many pregnant women can carry Listeria asymptomatically in their GI tract or vagina. Maternal infection with Listeria can result in chorioamnionitis, premature labor, spontaneous abortion, or stillbirth. Fetal infection can occur via transplacental transmission. Vertical transmission can also occur from mother to infant via passage through an infected birth canal or ascending infection through ruptured amniotic membranes. [12, 13] Nosocomial outbreaks from one infected infant to others in the same nursery are rare but have been reported.

Two clinical presentations of neonatal infections occur: early onset (< 5 d) and late onset (>5 d). Early onset neonatal listeriosis is usually associated with sepsis or meningitis. Late-onset neonatal listeriosis frequently presents with purulent meningitis (Gaschignard, 2011). Listeriosis often involves many organs with microabscesses or granulomas. A disseminated rash with small, pale, granulomatous nodules is histologically characteristic of granulomatosis infantisepticum. Beyond the neonatal period, most children with Listeria infections have an underlying immunodeficiency or are immunocompromised. Older children with Listeria infections frequently develop meningitis. [14, 15, 16]

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