Clinical Background
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
