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Pathogenic Corynebacterium & Listeria: Features and Epidemiology

Explore the distinguishing features, virulence factors, and epidemiology of pathogenic Corynebacterium species along with insights into Listeria monocytogenes infections. Understand the mechanisms of action of toxins and survival strategies of these gram-positive bacilli. Discover the common routes of human exposure to Listeria and the population at risk.

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Pathogenic Corynebacterium & Listeria: Features and Epidemiology

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  1. Corynebacterium Erysipelothrix & Listeria

  2. Pathogenic Anaerobic Gram-Positive Bacilli

  3. Corynebacteria (Genus Corynebacterium) ØAerobic or facultatively anaerobic ØSmall, pleomorphic (club-shaped), gram-positive bacilli that appear in short chains (“V” or “Y” configurations) or in clumps resembling “Chinese letters” ØCells contain metachromatic granules (visualize with methylene blue stain) ØLipid-rich cell wall contains meso-diaminopimelic acid, arabino-galactan polymers, and short-chain mycolic acids ØLysogenic bacteriophage encodes for potent exotoxin in virulent strains

  4. Mycobacterium Nocardia Corynebacterium     Distinguishing Features of CMN Group

  5. Pathogenic Corynebacterial Species • Corynebacterium diphtheriae • Corynebacterium jeikeium • Corynebacterium urealyticum

  6. Corynebacterium urealyticum • ØUrinary tract infections (UTI’s); rare but important • ØUrease hydrolyzes urea; release of NH4+, increase in pH, alkaline urine, renal stones

  7. Corynebacterium jeikeium • ØOpportunistic infections in immunocompromised (e.g., patients with blood disorders, bone marrow transplants, intravenous catheters) • ØMultiple antibiotic resistance common (MDR) • ØCarriage on skin of up to 40% of hospitalized patients (e.g., marrow t-plants)

  8. Percentage of Individuals Colonized Corynebacterium jeikeium Carriers

  9. Corynebacterium diphtheriae • ØRespiratorydiphtheria (pseudomembrane on pharynx) and cutaneous diphtheria • ØPrototype A-B exotoxin acts systemically • Toxoid in DPT and TD vaccines • ØDiphtheria toxin encoded by tox gene introduced by lysogenic bacteriophage (prophage) • ØSelective media: cysteine-tellurite; serum tellurite; Loeffler’s • ØGravis, intermedius, and mitis colonial morphology

  10. Epidemiology of Diphtheria

  11. Incidence of Diphtheria in the USA

  12. Incidence of Diphtheria in Former Soviet Union

  13. Virulence Factors in Corynebacterium Species

  14. Diphtheria tox Gene in Beta Bacteriophage and Prophage

  15. See Handout on Exotoxins

  16. Mechanism of Action of Diphtheria Toxin: Inhibition of Protein Synthesis

  17. Catalytic Region A Subunit B Subunit Translocation Region Receptor-Binding Region Molecular Structure of Diphtheria Toxin

  18. Heparin-binding epidermal growth factor on heart & nerve surfaces

  19. Immune Status to C. diphtheriae and Sensitivity to Diphtheria Toxoid TOXIN TOXOID Diagnostic Schick Skin Test

  20. In vivo Detection of Diphtheria Exotoxin

  21. Listeria monocytogenes • Gram-positive beta-hemolytic bacillus • Multiply at refrigerator temperatures (4oC) • Tumbling motility at room temperature • CAMP Test positive (like Group B Streptococcus)

  22. Where do we find 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

  23. Epidemiology of Listeriosis

  24. Natural Reservoirs Common Routes for Human Exposure Population at Greatest Risk Epidemiology of Listeria Infections

  25. 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 humoralimmunity develop • Only cell-mediated immunity is protective

  26. Methods That Circumvent Phagocytic Killing See Chpt. 19

  27. Intracellular Survival & Replication of Listeria Phagocytosis Macrophage Listeriolysin O? Macrophage Intracellular Replication Actin Filaments

  28. Erysipelothrix rhusopathiae • Gram-positive non-motile bacillus; forms filaments • Occupational disease of meat and fish handlers, hunters, veterinarians • Preventable withprotective 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

  29. Epidemiology of Erysipelothrix Infection

  30. REVIEW

  31. Corynebacterium diphtheriae • ØRespiratorydiphtheria (pseudomembrane on pharynx) and cutaneous diphtheria • ØPrototype A-B exotoxin acts systemically • Toxoid in DPT and TD vaccines • ØDiphtheria toxin encoded by tox gene introduced by lysogenic bacteriophage (prophage) • ØSelective media: cysteine-tellurite; serum tellurite; Loeffler’s • ØGravis, intermedius, and mitis colonial morphology REVIEW

  32. Diphtheria tox Gene in Beta Bacteriophage and Prophage REVIEW

  33. See Handout on Exotoxins REVIEW

  34. Mechanism of Action of Diphtheria Toxin: Inhibition of Protein Synthesis REVIEW

  35. Corynebacterium jeikeium • ØOpportunistic infections in immunocompromised (e.g., patients with blood disorders, bone marrow transplants, intravenous catheters) • ØMultiple antibiotic resistance common (MDR) • ØCarriage on skin of up to 40% of hospitalized patients (e.g., marrow t-plants) REVIEW

  36. Corynebacterium urealyticum • ØUrinary tract infections (UTI’s); rare but important • ØUrease hydrolyzes urea; release of NH4+, increase in pH, alkaline urine, renal stones REVIEW

  37. Listeria monocytogenes • Gram-positive beta-hemolytic bacillus • Multiply at refrigerator temperatures (4oC) • Tumbling motility at room temperature • CAMP Test positive (like Group B Streptococcus) REVIEW

  38. Natural Reservoirs Common Routes for Human Exposure Population at Greatest Risk Epidemiology of Listeria Infections REVIEW

  39. 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 humoralimmunity develop • Only cell-mediated immunity is protective REVIEW

  40. Intracellular Survival & Replication of Listeria Phagocytosis Macrophage Listeriolysin O? Macrophage Intracellular Replication Actin Filaments REVIEW

  41. Erysipelothrix rhusopathiae • Gram-positive non-motile bacillus; forms filaments • Occupational disease of meat and fish handlers, hunters, veterinarians • Preventable withprotective 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 REVIEW

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