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Pyogenic Coccus

Pyogenic Coccus. The Staphylococci. Morphology & Identification. Gram positive Facultative anaerobes Grape like-clusters Catalase positive Major components of normal flora skin nose. Gram Positive cocci - staphylococci. Pus. Catalase test （过氧化氢酶）. (-) (+).

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Pyogenic Coccus

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  1. Pyogenic Coccus

  2. TheStaphylococci

  3. Morphology & Identification • Gram positive • Facultative anaerobes • Grape like-clusters • Catalase positive • Major components of normal flora • skin • nose

  4. Gram Positive cocci - staphylococci Pus

  5. Catalase test（过氧化氢酶） (-) (+)

  6. Pathogenesis & Immunity of Staphylococcus aureus

  7. Antigenic Structure

  8. Protein A inhibits phagocytosis PHAGOCYTE Fc receptor Protein A immunoglobulin BACTERIUM

  9. Toxins & Enzymes • Catalase • Coagulase • Hyaluronidase and Lipase • Hemolysin or sphingomyelinase C • Leukocidin • Exfoliative Toxin • Toxic Shock Syndrome Toxin (superantigen) • Enterotoxins

  10. Pathogenesis

  11. Pathogenesis of staphylococcal infections Stye:麦粒肿 Carbuncle:痈 Impetigo：脓疱疮

  12. Infections associated with indwelling devices

  13. Superantigens and the non-specific stimulation of T cells

  14. Clinical Findings-Suppurative • A. (Skin) Furuncle; Protein A, Leukocidin, Hemolysin Stye; lipase Impetigo; contagious Epidermal necrolysis Exfoliative Dermatitis (6,7,8); Exfoliative toxin Mastitis Abscess (deep tissue); granulation; coagulase, hyaluronidase (burn, wound) • B. Systemic : Bactermia (from abscess, wound, burn) , Osteomyelitis (tibia) ,Pneumonia

  15. Clinical Findings-Food poisoning • not a human infection • food contaminated from humans • growth • enterotoxin • onset and recovery both occur within few hours • Vomiting/ nausea/ diarrhea/ abdominal /pain

  16. Toxic shock syndrome • fever • scarlatiniform rash • desquamation • vomiting • diarrhea • myalgias

  17. S. aureus • babies • scalded skin syndrome • exfoliatin

  18. Pseudomembranous Colitis

  19. Laboratory • A. Direct examination; Gram Stain • B. Primary media; BAP • C. Differential Tests. • Mannitol Salts • Coagulase • DNase • D. Phage typing • E. Antibiotic Sensitivity (plasmid, B lactamase) • penicillin /methicillin/vancomycin

  20. S. aureus on BAP

  21. Mannitol Salt Agar

  22. DNase test 0.1% Toluidine blue O (+): Pink 1N HCl (+) :

  23. S. aureus on potassium tellurite agar

  24. Lysostaphin test Staphylococcus Micrococcus

  25. API STAPH Kit

  26. Staphylococcus epidermidis • major component skin flora • opportunistic infections • less common than S.aureus • nosocomial infections • heart valves • Identification • Non-hemolytic (sheep blood agar) • Does not ferment mannitol • Non-pigmented • Coagulase-negative

  27. Staphylococcus saprophyticus • urinary tract infections • coagulase-negative • not differentiated from S. epidermidis

  28. The Streptococcus

  29. Streptococcus

  30. Morphology & Identification • facultative anaerobe • Gram-positive • Chainsor pairs • Catalasenegative (staphylococci are catalase positive)

  31. Cell surface structure of S pyogenes and extracellular substances

  32. S. pyogenes lipoteichoic acid F-protein fibronectin epithelial cells

  33. M protein • major target • natural immunity • strain variation • antigenicity • re-infection • occurs with different strain

  34. r r r r r r M protein IMMUNE Complement IgG M protein NON-IMMUNE peptidoglycan fibrinogen

  35. Capsules • Anti-phagocytic • mucoid strains

  36. Streptococci • Lancefield groups • one or more species per group • surface antigens

  37. groupablestreptococci • A, B and D • most important • C, G, F • rare

  38. Non-groupable • S. pneumoniae • pneumonia • viridans streptococci • e.g. S. mutans • dental caries

  39. Toxins & Enzymes

  40. Hemolysis alpha beta gamma

  41. Classofication of Streptococci of Particular Medical Interest

  42. Pathogenesis of S pyogenes infections.

  43. Group A streptococcal infections affect all ages peak incidence at 5-15 years of age

  44. S. pyogenes -suppurative • non-invasive • pharyngitis • skin infection, impetigo • invasive bacteremia • toxic shock-like syndrome • "flesh eating" bacteria • pyrogenic toxin

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