Corynebacteria

1. Corynebacteria Filename: Coryne.ppt

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

3. Corynebacterium: Habitat • Skin • upper respiratory tract • GI tract • Urogenital tract of humans

4. C. diphtheriaeDiphtheria C.pseudotuberculosishumans sheep, cattle, suppurative lymphadenitis C. ulceranshumans pharyngitis cattle -mastitis C. haemolyticumpharyngitis cutaneous infection C.pyogenes cattle, sheep, swine suppurative infection C.pseudodiphtheriticumendocarditis Cornyebacterium: Pathogens

5. C. xerosis opportunistic infections Group J K immunocompromised host

6. Related Organisms Listeria monocytogenes • Listeriosis • Erysipelothrix rhusiopathiae • Erysipeloid

7. Diphtheria

8. DiphtheriaLaboratory diagnosis • Speedy diagnosis • Differentiate from commensals • “diphteroids” • nose & throat • C. xerosis C. hofmanni • Throat swabs (confirmatory) • Blood Tellurite • Virulence test

9. Corynebacterium • Aerobic gram + rods • -pleomorphic: club-shaped • -pallisades • -snapping cell division • -metachromatic granules • methylene blue stain • volutin: polyphosphate

10. Cellular Morphology • Gram positive rods • “Snapping division” • Palisade cells • “Chinese letters” Erysipelothrix

11. Tellurite: black colonies Not diagnosticallly significant tellurite inhibits many organisms but not C. diphtheriae Loeffler best colonial morphology Dextrose horse serum (1887) now Dextrose beef serum Specialized media

12. Blood tellurite • Selective & differential medium • Corynebacteria are resistant to tellurite • Reduced to tellurium • Forms deposit in colonies • Colonies appear dark • Biotypes • gravis, intermedius, mitis

13. Corynebacterium Biotypes • C diphtheriaegravis • C diphtheriaeintermedius • C diphtheriaemitis • Helpful for epidemiological tracing • Culture identified by biochemical tests.

14. Diphtheria • Nasopharyngeal diphtheria • Pharyngeal • Larygngeal • Cutaneous diphtheria • Systemic complications DIAGNOSIS MUST BE CLINICAL!!!!

15. Pharyngeal diptheria • Inflammation • similar to strept throat • Leucocytes • infiltrated • killed • embedded in fibrin clot • TOXIN !!

16. Diphtheria Symptoms • Pharyngitis • Hypoxia • Choking • “Garitillo” • Fever (103 F) • Lymphadenitis All SIGNS & SYMPTOMS CAUSED BY TOXIN

17. Diphtheria Pseudomembrane • No True membrane • Very few live cells • Deposit of dead cells and protein

18. COVERS tonsils, uvula, palate nasopharynx larynx. Pseudomembrane • CONTAINS • bacteria • lymphocytes • plasma cells • fibrin • dead cells

19. DiphtheriaSystemic complications • Nerves • toxic peripheral neuropathy • paralysis of short nerves • mouth, eye, facial extremities • Cardiac • Congestive heart failure • high amount of toxin 48-72 hours • Low amount of toxin 2-6 weeks

20. Virulence Factors • Diphtheria toxin !!! • blocks protein synthesis • Dermonecrotic toxin • sphingomyelinase • increases vascular permeability • Hemolysin • Cord factor -Toxic trehalose • corynemycolic acid, corynemyolenic acid • 6,6’-di-O-mycoloyl- a,a’-D-trehalose

21. DiphtheriaToxin • Blocks protein synthesis • Protein 63Kd • controlled by Tox gene • lysogenic phage Beta-corynephage • expressed if [iron] low • 2 components A-B

22. Regulation of Diphtheria Toxin High [Fe 2+] NO Toxin Produced P o tox Corynebacteriophage beta Fe 2+ + apo DtxR [Fe 2+*DtxR] p dtxR C diphtheriae dtxR= repressor protein

23. P o tox Corynebacteriophage beta Regulation of Diphtheria Toxin Low [Fe 2+] Toxin Produced!!! Fe 2+ + apo DtxR [Fe 2+*DtxR]

24. Toxin • Part A • Active site • N terminal • Enzyme • Part B • Binding site • Binds to membrane receptor • Transmembrane

25. Diphtheria toxin: Part A • Active site • Enzyme • Blocks protein synthesis • ADP-ribosyl transferase • elongation factor 2 (EF2) • Specific for mammalian cells • Prokaryotes have different EF2

26. Diphtheria Toxin: Part B • Binding Site • Binds to cell receptor • Bound receptor internalized • Endosome • Hydrolysed by protease • Disulfide broken • Part A released

27. A A A B B B A B Activation of Diphtheria Toxin

29. Toxingenicity Tests In Vitro Elek test In Vivo Animal inoculation rabbit skin test-necrosis guinea pig challenge test- lethal low [Fe 2+] induces toxin

30. Elek test

31. Animal inoculation Inject 2 mice with 5ml C.diphtheria cells one mouse protected with 1000 units C.diphtheriae antitoxin Autopsy - adrenals hemorrhagic

32. Control • Immunization diphtheria toxoid • Schick test • check for antibodies • Passive immunity • Antibodies • Antibiotics • Penicillin & erythromcyin

33. Schick Test for Diptheria

34. Epidemics • Immune individuals • may be carriers • antibiotics • Non immune individuals • Exposed • passive immunity antibodies • Not exposed • immunize with toxoid

35. Diphtheria: Russian Federation

36. Diphtheria in the Soviet Union and NIS Emerging infectious diseases: 4(4) 1998 Vitek & Wharton

37. Diphtheria Incidence

38. Diphtheria in the Russian Federation

39. The End

40. Performance Objectives Key terms, concepts short answers

41. pseudomembrane Key Terms

42. Schick test Elek Test Diphtheria toxin larnygeal diphtheria pharyneal diphtheria Key Terms

43. Corynebacterium Listeria Erysipelothrix Key Organisms

44. Key Concepts

45. Epidemiology of Diphtheria • Disease/bacterial factors • Transmission • Who is at risk • Geography/ season • Incidence • Modes of control

46. Short Answers • Construct a table of the virulence factors associated with diphtheria and the biological activity of each • Use a series of no more than four diagrams to describe the mechanism of action of diphtheria toxin • Describe the clinical manifestations of diphtheria • Construct a table listing the common Corynebacteria and the associated diseases.