Listeria monocytogenes presentation pdf.pdf

Listeria monocytogenes presentation pdf.pdf

1. Listeria
monocytogenes
case study

2. Case13: meningitis by Listeria monocytogenes
A 55-year-old male farmer patient was hospitalized because of headache,
fever, and confusion. He reports eating left over cold salads and drank
unpasteurized milk. He had received a liver transplant 7 months earlier, and
takes immunosuppressive drugs to prevent organ rejection. CSF was
collected. Gram-positive bacilli grew in cultures of the blood and CSF.

3. GUIDED QUESTIONS
1.Whatisthemostlikelyagentresponsibleforthispatient’s
meningitis?
2.Whatarethesourcesofthisorganism?
3.Whatvirulencefactorsareassociatedwiththisorganism?

4. Q1:What is the most likely agent responsible for this
patient’s meningitis?
The most likely agent responsible for this patient's
meningitis is Listeria monocytogenes. This conclusion
is based on the patient’s symptoms (headache, fever,
confusion), history of consuming unpasteurized milk
and cold salads (common sources of Listeria), and the
presence of Gram-positive bacilli in the CSF and blood
cultures. Additionally, the patient's
immunocompromised status due to
immunosuppressive drugs post-liver transplant
increases susceptibility to Listeria infection.

5. Q2:What are the sources of this organism?
Sources of Listeria monocytogenes:
-Food Products: Unpasteurized milk and dairy products, soft cheeses, cold salads, deli meats, hot
dogs, and smoked seafood are common sources.
-Environmental: Soil, water, and decaying vegetation can harbor Listeria, potentially contaminating
crops and livestock.
-Animals: Listeria can be found in the intestines of many animals, leading to contamination of meat
products and dairy.

6. What is the pasteurization???????
Pasteurization is a process that involves heating a liquid, usually milk, to a specific temperature for
a set period to kill harmful bacteria and pathogens without significantly affecting the taste or
nutritional value. The process is named after Louis Pasteur, who developed it in the 19th century.

7. Q3:What virulence factors are associated with this
organism?
▪Internalin (InlA& InlB):
•It binds to glycoprotein receptors on the epithelial cells lining the gastro-intestinal tract.
•It facilitates ingestion of organism by macrophages, endothelial cells etc
•It become internalized in a membrane-bound vacuole.
▪ListeriolysinO (LLO):
•formation of pores avoiding intracellular killing.
•Major virulence factor
▪Actin polymerization (ActA):
•Actin tails enable Listeria to be motile and spread directly from cell to cell.
•Rocket-like tails containing F-actin
•Helps the bacteria move within and between cells
▪Phospholipases (Plc):
•Helps the bacteria escape host cell vacuole and cause membrane disruption
•It helps cell to cell spread of the bacteria

9. Thank you for your attention!!!!!