Listeria infection general information; etiology, transmission, pathogenesis, symptoms, Listeriosos, risk groups, pregnant patients, infection in fetus and neonate, infection in elderly, diagnosis, treatment, prevention

1. Listeria infection

2. Etiology
• Species L. monocytogenes
• Gr+
• Aerobic
• Motile with its 1-5 flagella
• Non-spore forming
• Rodlike

3. Transmission
• L. monocytogenes infects many domestic and wild animals
• Transmitted to humans by eating infected animals or animal
products

4. Pathogenesis
• Enters the human body by ingesting the contaminated food
• Has virulence factor listeriolysin O that allows it to escape the
phagolysosomes of macrophages and avoid intracellular killing

5. Symptoms of Listeriosis
• Mild symptoms:
• Fever
• Muscle aches
• Nausea
• Diarrhea
• Severe symptoms:
• Meningitis
• Mental changes
• Brain abscess
• Death

6. People at risk of infection
• Pregnant women
• Fetus and neonate
• Elderly and immunocompromised

7. Infection in pregnant woman
• Usually occurs in third semester when the cell-mediated
immunity decreases
• The bacteria infects the fetus and 22% of these infections
result in neonatal death
• Surviving babies are often born prematurely with active
infection
• Prophylaxis: pregnant women should avoid milk, soft cheeses,
butter and deli meals

8. Infection in fetus and neonate
• Infection is acquired in utero
• Can also be contracted from an asymptomatic mother, with
vaginal colonization with Listeria during vaginal birth
• This type of infection results in neonatal meningitis presenting
about 2 weeks post-partum
• Listeria monocytogenes causes 20% of all neonatal meningitis

9. Infection in elderly and
immunocompromised
• Is the second most common cause of meningitis, after
Pneumococcus, in people over 50 years old
• Immunocompromised patients at risk are:
• Patients with lymphoma
• Patients receiving organ transplantation
• Patients on corticosteroids
• Patients with AIDS

10. Infection in immune
component hosts
• Listeria monocytogenes is a facultative intracellular organism
• In immune component host it is not likely to cause infection
due to cell-mediated immunity

11. Diagnosis
• Confirmed by lumbar puncture
• Cerebrospinal fluid analysis reveals a high number of
neutrophils, increased protein level, decreased glucose level
• Positive gram stain showing gram-positive rods

12. Treatment
• Fluid 0,9% NaCl
• By antibiotics:
• Ampicillin
• Children: 75 mg/kg/day
• Adults: 150 mg/kg/day
• Trimethoprimsulfamethoxazole
• Children: 2x100mg/day
• Adults: 2x400mg/day

13. Prevention
• Cook food properly at high temperature
• Treating/pasteurizing fluids
• Avoid food or fluids that might have been in contact with
animals or human waste

14. Sources
• http://www.medicinenet.com/listeria/article.htm
• Lange: medical microbiology
• Andreas Russ: Arzneimittel pocket