II. Pathophysiology
- Non-spore forming Gram Positive Rod (Diphtheroid similar to Corynebacterium)
- Facultative Anaerobe, and able to grow at cold Temperatures (4 to 10 C)
- Flagella which result in a tumbling-type of motility
- Listeriolysin O is a virulence factor produced by Listeria
- Activated in the acidic environment of Phagosomes (e.g. Macrophages)
- Results in cytolysis of Macrophages, resulting in release of Listeria monocytogenes
- Listeriolysin O allows for Listeria to survive within immune cells as a facultative Intracellular Organism
- Immunocompetent patients can destroy intracellular Listeria
- However, Immunocompromised patients are enable to fully eradicate intracellular Listeria
- References
- Gladwin, Trattler and Mahan (2014) Clinical Microbiology, Medmaster, Fl, p. 59-61
III. Causes: Sources
- See Foodbourne Illness
- Deli Meat
- Frozen Vegetables (2016 outbreak in U.S.)
- Unpasteurized milk (including derived soft cheese, cole slaw, butter)
IV. Risk Factors: Severe, invasive disease
- Elderly or Immunocompromised patients (e.g. Lymphoma, Corticosteroids, organ transplant, AIDS)
- Listeria is among the most common Meningitis causes in this cohort
- Pregnancy
- Typically, affects women in the third trimester, resulting in bacteremia and Sepsis
- Affects the fetus in nearly one quarter of cases resulting in neonatal death or premature birth
- Newborns
- Infection may be acquired via Vaginal Delivery in asymptomatic, colononized mothers
- Results in Neonatal Sepsis and Meningitis, most commonly presenting at 2 weeks of life
V. Symptoms
- Onset
- Gastrointestinal symptoms start within 9 to 48 hours
- Immunocompetent hosts typically have self-limited course
- Invasive disease onset delayed for 2 to 6 weeks
- Gastrointestinal infection
- Invasive infection (esp. Immunocompromised patients)
- Bacteremia
- Meningitis
- Endocarditis
- Pregnancy (presents with flu-like illness)
- Premature delivery
- Stillbirth
VI. Labs
- Missed on Stool Culture
VII. Management
- See Acute Diarrhea
-
Antibiotics
- Not typically used (self-limited disease in normal hosts)
- Consider in severe, invasive cases or high risk patients (5 days Amoxicillin or Septra has been used)
VIII. Resources
- CDC Listeria