2. Corynebacterium
Erysipelothrix
& Listeria

3. Pathogenic Anaerobic Gram-Positive Bacilli

4. 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

5. C32H62O3 = Corynemycolic acid
C32H64O3 = Corynemycolenic acid
Cord factor = فاکتور طناب، ماده ای سمی است که از طریق دیواره به بیرون از سلول ترشح می شود و با کمک آنتی ژن (اچ)درسلولهای مخاطی فرورفته باعث ترکا ندن میتوکندریهای آنها و بالاخره ممانعت ازفسفریلاسیون وتنفس در این سلولها می گردد.

6. Distinguishing Features of CMN Group
Corynebacterium
Mycobacterium
Nocardia 

7. Pathogenic Corynebacterial Species
Corynebacterium diphtheriae
Corynebacterium jeikeium
Corynebacterium urealyticum

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

9. 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)

10. Corynebacterium jeikeium Carriers
Percentage of Individuals Colonized

11. Corynebacterium diphtheriae
ØRespiratory diphtheria (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

12. Epidemiology of Diphtheria

13. Incidence of Diphtheria in the USA

14. Incidence of Diphtheria in Former Soviet Union

15. Virulence Factors in Corynebacterium Species

16. Diphtheria tox Gene in Beta Bacteriophage and Prophage

17. See Handout on Exotoxins

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

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

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

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

23. In vivo Detection of Diphtheria Exotoxin

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

26. 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

27. Epidemiology of Listeriosis

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

29. Listeriosis Neonates, elderly & immunocompromised
Granulomatosis infantiseptica
Transmitted to fetus transplacentally
Early septicemic form: 1-5 days post-partum
Delayed meningitic form: days following birth
Intracellular pathogen
Cell-mediated and humoral immunity develop
Only cell-mediated immunity is protective

30. Methods That Circumvent Phagocytic Killing
See Chpt. 19

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

33. 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

34. Epidemiology of Erysipelothrix Infection

36. REVIEW

37. Corynebacterium diphtheriae
ØRespiratory diphtheria (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

38. Diphtheria tox Gene in Beta Bacteriophage and Prophage
REVIEW

39. See Handout on Exotoxins
REVIEW

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

41. 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

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

43. 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

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

45. Listeriosis Neonates, elderly & immunocompromised
Granulomatosis infantiseptica
Transmitted to fetus transplacentally
Early septicemic form: 1-5 days post-partum
Delayed meningitic form: days following birth
Intracellular pathogen
Cell-mediated and humoral immunity develop
Only cell-mediated immunity is protective
REVIEW

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

47. 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
REVIEW