1. Listeria & Erysipelothrix
Filename: Listeria.ppt

2. Outline Microbes Diseases Corynebacterium,Listeria, Erysipelothrix
Diphtheria,Listeriosis, Erysipeloid

3. Listeriosis

4. Listeria monocytogenes
short , motile,non-spore - forming, Grm + rods, - hemolytic, looks like Group B streptococcus but group B is catalase neg and non-motile.
found in wild and domestic animals excreted into soils
healthy human carriers 5-10 %
source of infection is food and animal contact.

5. Listeria Infections Neonatal sepsis or meningitis
Spontaneous abortion or still birth
Sepsis or meningitis in immunocompromised patients
Puerperal sepsis
Persons at risk: Pregnant, post partum, new born, organ transplants

6. Listeriosis Disease of humans Sepsis Meningitis + encephalitis
25% mortality

7. Listeria Pathogenesis
Ingested raw contaminated food
Penetrates cell of intestine
common event
most have T cells
Facultative intracellular pathogen
Immunocompromised host
Transmitted congenitally

8. Listeriosis Diagnosis
Monocytosis
Peripheral blood & cerebrospinal fluid
Gram stain
Gram positive rods in CFS
Culture
Blood, CSF, skin lesions

9. Listeria: Virulence Factors
Internalin an invasion factor controlled by the inl A gene
The organisms are taken into the cell by forced phagocytosis, become enclosed in a vesicle and rupture it.
Listeriolysin - alpha hemolysis hly gene.
Lecithinase - hemolysin Phospholipase

10. Listeria: Food poisoning
MILK and dairy products. This species grows at refrigerator temp. 5-12o C
Isolated by cold enrichment.

11. Test for Listeria in Milk
Add fluorescent-labelled antibodies specific for Listeria monocytogenes to milk
Pass through a flow cytometer. fluid is passed through a small opening
Listeria detected by a laser beam
NO CULTURE NEEDED!!!

12. Listeriosis Prevention
Persons at risk
avoid soft cheeses and unpasteurized milk and processed meat that cannot be cooked.
thoroughly cook all meats especially hot dogs
left over meat should be cooked to steaming.

13. Listeriosis Control Hygienic food processing Antimicrobial agents
contaminated vegetables
vinegar in salads
Antimicrobial agents
Not cephalosporins
Ampicllin + aminoglycoside
bacteriostatic

14. Erysipeloid

15. Erysipelothrix pathogenesis
Skin lesions
fingers or hand
violet or wine coloured
Occasionally septicemia
endocarditis
afebrile arthritis

16. Erysipelothrix rhusiopathiae
Gram positive rods
Grow aerobically
prefer 7% carbon dioxide
Non motile
Non hemolytic
Produce hydrogen sulfide

17. Erysipelothrix Epidemiology
Found in mammals, poultry & fish
Farmers, vets, slaughterhouse workers, fish handlers

18. Erysipelothrix Diagnosis & Control
Typical lesions
Occupation
Blood culture if sepsis
Control
Self limiting
Penicillin if complications

19. The End

20. Performance Objectives
Key terms, concepts
short answers

21. Key Terms

22. Key Terms

23. Key Organisms
Corynebacterium
Listeria
Erysipelothrix

24. Key Concepts

25. Epidemiology of Listeriosis
Disease/bacterial factors
Transmission
Who is at risk
Geography/ season
Incidence
Modes of control

26. Short Answers
Construct a table of the virulence factors associated with listeriosis and the biological activity of each
Describe the clinical manifestations of listeriosis
Construct a table listing the common Corynebacteria and the associated diseases.