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Corynebacterium Erysipelothrix       &    Listeria
Pathogenic AnaerobicGram-Positive Bacilli
1. Corynebacteria (Genus Corynebacterium)Aerobic or facultatively anaerobicSmall, pleomorphic (club-shaped), gram-positi...
Distinguishing Features of CMN Group               Corynebacteriu   Mycobacterium   Nocardia                    m
Pathogenic Corynebacterial SpeciesCorynebacterium diphtheriaeCorynebacterium jeikeiumCorynebacterium urealyticum
Corynebacterium urealyticumUrinary tract infections (UTI’s); rare butimportantUrease hydrolyzes urea; release of NH4+,in...
Corynebacterium diphtheriaeRespiratory diphtheria (pseudomembrane onpharynx) and cutaneous diphtheriaPrototype A-B exoto...
Epidemiology of  Diphtheria
Virulence Factors in Corynebacterium Species
Diphtheria tox Gene in Beta Bacteriophage    and Prophage
See Handout on Exotoxins
Mechanism of Action of Diphtheria Toxin:       Inhibition of Protein Synthesis
Molecular Structure of Diphtheria Toxin             Catalytic Region                                A Subunit             ...
Heparin-binding epidermal growth factor on heart & nerve surfaces
Diagnostic Schick Skin TestImmune Status to C. diphtheriae and  Sensitivity to Diphtheria Toxoid         TOXIN    TOXOID
In vivo Detectionof Diphtheria Exotoxin
2. Genus Listeria
2.Listeria monocytogenes• Small, Gram +, nonsporing rod• End-over-end tumbling motility when grown at  20-25°C, not at 37°...
Listeriosis• Humans, domestic animals  described in ≥ 40 species of animals  usually follows ingestion  outbreaks, spor...
ListeriosisNeonates, elderly & immunocompromisedGranulomatosis infantiseptica  • Transmitted to fetus transplacentally  ...
Distribution of Listeria?Intestinal tract of mammals & birds (especially chickens)Persists in soilSoft cheeses & unwash...
Epidemiology of Listeria Infections Natural     Common Routes for       Population atReservoirs    Human Exposure         ...
Virulence Factors and Pathogenesis -                   Motility• Actin-mediated motility (ActA)  host cell actin polymeri...
Virulence Factors and Pathogenesis• After entry to epithelial  cells  escapes phagosome,   multiplies in cytoplasm  exoc...
Virulence Factors and Pathogenesis -                Listeriolysin• Major virulence factor: listeriolysin  thiol-activated...
Virulence Factors and Pathogenesis• Bacteria encountering plasma  membrane continue to move  forward   produce protrusion...
Virulence Factors and Pathogenesis -             Actin-based Motility• Bacteria in cytoplasm  polymerize actin, form  tail...
Intracellular Survival & Replication of Listeria        Phagocytosis                                         Macrophag    ...
Immune Response• In infected mice, bacteria first appear in MØ, then  invade hepatocytes   most replication probably occu...
bacteria released from lysed host cells killed bv activated MØT cell-deficient mice survive infection: cytotoxic T-cell ...
Erysipelothrix rhusopathiaeGram-positive non-motile bacillus; forms filamentsOccupational disease of meat and fish handl...
Epidemiology of  Listeriosis
Epidemiology of Listeria Infections Natural     Common Routes for   Population atReservoirs    Human Exposure     Greatest...
ListeriosisNeonates, elderly & immunocompromisedGranulomatosis infantiseptica  • Transmitted to fetus transplacentally  ...
Methods That Circumvent Phagocytic              Killing                               See Chpt. 19
Intracellular Survival & Replication of Listeria      Phagocytosis                                           Macrophage   ...
3. Erysipelothrix rhusopathiaeGram-positive non-motile bacillus; forms filamentsOccupational disease of meat and fish ha...
Epidemiology of Erysipelothrix   Infection
Pathogenic anaerobe gram positive bls 206
Pathogenic anaerobe gram positive bls 206
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Transcript of "Pathogenic anaerobe gram positive bls 206"

  1. 1. Corynebacterium Erysipelothrix & Listeria
  2. 2. Pathogenic AnaerobicGram-Positive Bacilli
  3. 3. 1. Corynebacteria (Genus Corynebacterium)Aerobic or facultatively anaerobicSmall, pleomorphic (club-shaped), gram-positivebacilli that appear in short chains (“V” or “Y”configurations) or in clumps resembling “Chineseletters”Cells contain metachromatic granules (visualizewith methylene blue stain)Lipid-rich cell wall contains meso-diaminopimelic acid, arabino-galactan polymers,and short-chain mycolic acidsLysogenic bacteriophage encodes for potentexotoxin in virulent strains
  4. 4. Distinguishing Features of CMN Group Corynebacteriu Mycobacterium Nocardia  m
  5. 5. Pathogenic Corynebacterial SpeciesCorynebacterium diphtheriaeCorynebacterium jeikeiumCorynebacterium urealyticum
  6. 6. Corynebacterium urealyticumUrinary tract infections (UTI’s); rare butimportantUrease hydrolyzes urea; release of NH4+,increase in pH, alkaline urine, renal stones
  7. 7. Corynebacterium diphtheriaeRespiratory diphtheria (pseudomembrane onpharynx) and cutaneous diphtheriaPrototype A-B exotoxin acts systemically • Toxoid in DPT and TD vaccinesDiphtheria toxin encoded by tox gene introducedby lysogenic bacteriophage (prophage)Selective media: cysteine-tellurite; serumtellurite; Loeffler’sGravis, intermedius, and mitis colonial morphology
  8. 8. Epidemiology of Diphtheria
  9. 9. Virulence Factors in Corynebacterium Species
  10. 10. Diphtheria tox Gene in Beta Bacteriophage and Prophage
  11. 11. See Handout on Exotoxins
  12. 12. Mechanism of Action of Diphtheria Toxin: Inhibition of Protein Synthesis
  13. 13. Molecular Structure of Diphtheria Toxin Catalytic Region A Subunit B Subunit Translocation Region Receptor-Binding Region
  14. 14. Heparin-binding epidermal growth factor on heart & nerve surfaces
  15. 15. Diagnostic Schick Skin TestImmune Status to C. diphtheriae and Sensitivity to Diphtheria Toxoid TOXIN TOXOID
  16. 16. In vivo Detectionof Diphtheria Exotoxin
  17. 17. 2. Genus Listeria
  18. 18. 2.Listeria monocytogenes• Small, Gram +, nonsporing rod• End-over-end tumbling motility when grown at 20-25°C, not at 37°C• Facultative anaerobe, ß-hemolytic• CAMP Test positive (like Group B Streptococcus)
  19. 19. Listeriosis• Humans, domestic animals described in ≥ 40 species of animals usually follows ingestion outbreaks, sporadic cases related to food asymptomatic fecal carriage common, especially for those in contact with domestic animals Incidence increases in summer, when outbreaks of food-borne disease are more common.
  20. 20. ListeriosisNeonates, elderly & immunocompromisedGranulomatosis infantiseptica • Transmitted to fetus transplacentally • Early septicemic form: 1-5 days post-partum • Delayed meningitic form: 10-20 days following birthIntracellular pathogen • Cell-mediated and humoral immunity develop • Only cell-mediated immunity is protective
  21. 21. Distribution of Listeria?Intestinal tract of mammals & birds (especially chickens)Persists in soilSoft cheeses & unwashed raw vegetablesRaw or undercooked food of animal origin  Luncheon meats  Hot dogsLarge scale food recalls have become common
  22. 22. Epidemiology of Listeria Infections Natural Common Routes for Population atReservoirs Human Exposure Greatest Risk
  23. 23. Virulence Factors and Pathogenesis - Motility• Actin-mediated motility (ActA) host cell actin polymerized growth of tail by actin polymerization at end of bacterium propels it through cytoplasm• Uptake: induced phagocytosis internalin similar to M protein of S. pyogenes (antiphagocytic), dissimilar functions
  24. 24. Virulence Factors and Pathogenesis• After entry to epithelial cells escapes phagosome, multiplies in cytoplasm exocytosis from epithelial cell followed by phagocytosis by MØ, PMN multiplication followed by death of phagocytes, secondary phagocytosis systemic spread
  25. 25. Virulence Factors and Pathogenesis - Listeriolysin• Major virulence factor: listeriolysin thiol-activated cytolysin, hemolysin mediates escape from phagocytic vesicle• LLO mutants: LD50 5 logs higher than WT, do not survive in MØ
  26. 26. Virulence Factors and Pathogenesis• Bacteria encountering plasma membrane continue to move forward  produce protrusions extending into adjacent cell: listeriopods  escape listeriopod in double- membrane vesicle, enter cytoplasm of adjacent cell• Mediated by phospholipase
  27. 27. Virulence Factors and Pathogenesis - Actin-based Motility• Bacteria in cytoplasm polymerize actin, form tails  hollow mesh forms on surface, left behind as bacterium moves forward  invade adjacent cells• Actin nucleating factor: ActA  ActA localized at one end of the bacterium, not found in tail
  28. 28. Intracellular Survival & Replication of Listeria Phagocytosis Macrophag e Listeriolysin O? Macrophag e Intracellula Actin r Filaments Replication
  29. 29. Immune Response• In infected mice, bacteria first appear in MØ, then invade hepatocytes  most replication probably occurs in liver  infection of MØ leads to presentation of antigens with MHC class I, stimulating cytotoxic T cell response  cytotoxic T cells (and NK cells) kill infected hepatocytes
  30. 30. bacteria released from lysed host cells killed bv activated MØT cell-deficient mice survive infection: cytotoxic T-cell response helps clear hepatocytes, not essentialincreased susceptibility in mice unable to produce IFN-: suggests importance of activated MØ
  31. 31. Erysipelothrix rhusopathiaeGram-positive non-motile bacillus; forms filamentsOccupational disease of meat and fish handlers,hunters, veterinarians  Preventable with protective gloves & clothingErysipeloid in humans; erysipelas in swine & turkeys  Organisms enter through break in skin  Nonsuppurative, self-limiting skin lesions with erythema and eruption  Peripheral spread may lead to generalized infection, septicemia and/or endocarditis  Organisms can be isolated from skin biopsy
  32. 32. Epidemiology of Listeriosis
  33. 33. Epidemiology of Listeria Infections Natural Common Routes for Population atReservoirs Human Exposure Greatest Risk
  34. 34. ListeriosisNeonates, elderly & immunocompromisedGranulomatosis infantiseptica • Transmitted to fetus transplacentally • Early septicemic form: 1-5 days post-partum • Delayed meningitic form: 10-20 days following birthIntracellular pathogen • Cell-mediated and humoral immunity develop • Only cell-mediated immunity is protective
  35. 35. Methods That Circumvent Phagocytic Killing See Chpt. 19
  36. 36. Intracellular Survival & Replication of Listeria Phagocytosis Macrophage Listeriolysin O? Macrophage Intracellular Actin Replication Filaments
  37. 37. 3. Erysipelothrix rhusopathiaeGram-positive non-motile bacillus; forms filamentsOccupational disease of meat and fish handlers,hunters, veterinarians  Preventable with protective gloves & clothingErysipeloid in humans; erysipelas in swine & turkeys  Organisms enter through break in skin  Nonsuppurative, self-limiting skin lesions with erythema and eruption  Peripheral spread may lead to generalized infection, septicemia and/or endocarditis  Organisms can be isolated from skin biopsy
  38. 38. Epidemiology of Erysipelothrix Infection
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