Listeria

Listeria

 

Listeria monocytogenes is transmitted by consumption of contaminated foods.

Epidemiology

  • Increased incidence since the 1990s
  • Transmission – food-borne via contaminated milk and dairy products, various meats and fresh produce

Organism

  • Gram-positive rod
  • Organism produces flagella at room temperature, but not at 37ºC (body temperature)
  • L. monocytogenes is the only recognized human pathogen in Listeria species
  • Very hardy organism capable of growing at both 4ºC and 37ºC
  • >14 serotypes

Risk Factors

  • Cancer
  • Immunocompromised state (corticosteroids, transplant drugs)
  • HIV/AIDS
  • Age >60 years
  • Alcohol/chronic liver disease
  • Diabetes mellitus
  • Pregnancy

Clinical Presentation

  • Initial symptoms are typically fever, muscle aches, nausea, or diarrhea
    • If infection spreads, then more serious symptoms may develop
  • Sepsis
  • Central nervous system infection
    • Meningitis
    • Meningoencephalitis
  • Gastroenteritis
  • Localized infection
    • Skin
    • Intra-abdominal
  • Manifestations in pregnancy
    • Sepsis
    • Spontaneous or septic abortion
    • Still birth

Treatment

  • Difficult to treat; high fatality (30% rate)
  • Antibiotics are mandated for symptomatic disease

Prevention

  • Wash vegetables, heat foods to 160º, avoid soft cheese, do not drink raw (unpasteurized) milk