Ok s. aureus mehre 92

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Bacteriology2, Session 1, 26bahman1392, Professor Havaii(PHD)

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Ok s. aureus mehre 92

  1. 1. STAPHYLOCOCCI
  2. 2. STAPHYLOCOCCUS • • • • • • • • Introduction Classification Antigenic Structure Staphylococcal Enzymes Staphylococcal Toxins Pathogenesis Resistance to antibiotics Treatment
  3. 3. Staphylococcus • • • • • • F. Micrococcaceae G. Staphylococcus G. Micrococcus G. Stomatococcus G. Planococcus (facultative anaerobic) (only aerobic) (facultative anaerobic) (only aerobic)
  4. 4. INTRODUCTION • Staphyloccocci - derived from Greek “stapyle” (bunch of grapes) • Gram positive cocci arranged in clusters • Hardy organisms surviving many non physiologic conditions • Include a major human pathogen and skin commensals
  5. 5. Gram Stain of Staphylococcus Culture Gram-positive cocci predominately in clusters
  6. 6. Spread of Hospital Strain of Staphylococcus aureus Nurse (Carrier) Doctor: Boil Salesman: Carrier and Paronychia Son: Impetig o
  7. 7. Properties of Staphylococcus species Species S. aureus Catalase Coagulase positive S. epidermidis positive Mannitol Novobiocin positive positive sensitive negative negative sensitive S. saphrophyticus positive negative negative resistant
  8. 8. Grouping for Clinical Purposes • 1. Coagulase positive Staphylococci – Staphylococcus aureus • 2. Coagulase negative Staphylococci – Staphylococcus epidermidis – Staphylococcus saprophyticus
  9. 9. A. Staphylococcus aureus • Major human pathogen • Habitat - part of normal flora in some humans and animals • Source of organism - can be infected human host, carrier, or environment
  10. 10. 2. Staphylococcus epidermidis • Skin commensal • Infection of an implanted device such as heart valve, intravenus catheter. • Ass. With infection of prosthetic • Causes urinary tract infection in cathetarised patients • Usually resistant to many drugs.
  11. 11. 3. Stapylococcus saprophyticus • Skin commensal • Imp. Cause of UTI in sexually active young women • UTI in men (usually after age 50) • Cystitis, pyelonephritis
  12. 12. Resistance to antibiotics – β- lactamase production - plasmid mediated Has made S. aureus resistant to penicillin group of antibiotics - 90% of S. aureus • Resistance to Naficillin-OxacillinMethicillin • (Chromosomal mediated) • Tolerance • Resistance to Tetracyclin- ErythromycinAminoglycosides ( plasmid mediated )
  13. 13. • Tested in lab using methicillin • Referred to as methicillin resistant S. aureus (MRSA) • Emerging problem in the world • In Sri Lanka prevalence varies from 20- 40% in hospitals • Drug of choice - vancomycin • In Japan emergence of VIRSA(vancomycin intermediate resistant S. aureus) • No effective antibiotics discovered -We might have to discover
  14. 14. Antigenic structure • • • • Capsule Peptidoglycan Teichoic acid Protein A
  15. 15. Staphylococcus Structural Virulence Factors = peptidoglycan = capsule = PNSG (biofilm) = clumping factor = fibronectin binding protein = protein A = collagen binding protein = teichoic acid
  16. 16. Structural Carbohydrates and Virulence Peptidoglycan Inflammatory Teichoic Acid Inflammatory & allergen Capsule* Anti-phagocytic PNSG* Biofilm * - Antibodies to these carbohydrates are protective
  17. 17. Staphylococcal binding sites • The binding sites allow staphylococci to persist in areas where these substances abound. • Fibronectin, • C1q • Lamanin (glycoprotein in mammalian basement membranes) • Colagen
  18. 18. S. aureus Exoproteins and Virulence Hemolysins: alpha-hemolysin beta-hemolysin gamma-hemolysin delta-hemolysin Proteases Coagulase Hyaluronidase(s) Staphylokinase Lipase(s) Protease V8 tissue damage at site of infection tissue damage correlates with virulence spreading factors destroy host defense
  19. 19. Staphylococcal Enzymes • • • • • • • Coagulase Catalase Hyaluronidase Fibrinolysine Lipases Nucleases Penicillinase
  20. 20. Toxins - Cytotoxins (α , β ,γ) - Leukocidin - Exfoliative toxins (ETA , ETB) - Enterotoxins (A-F , G-I and three subtype C) - SEB (super Ag) - Toxic Shock Syndrom toxin-1 (super Ag)
  21. 21. α , β ,γ -hemolysin • • • • Toxic for : leukocytes , erythrocytes, macrophages and platelets Lymphocytes
  22. 22. DISEASES • Due to direct effect of organism – Local lesions of skin – Deep abscesses – Systemic infections • Toxin mediated – Food poisoning – toxic shock syndrome – Scalded skin syndrome
  23. 23. Sites of Staphylococcus Infections and Toxic Reactions Brain and Eye Infections Endocarditis Scalded Skin Syndrome (toxin) Nasopharynx 4+ Pneumonia Food Poisoning (toxin) Toxic Shock Syndrome vagina 4+ Pyoderma Bone/Joint Infection
  24. 24. Conditions Leading to S. aureus Infections Skin damage: burns, cuts, sutures Reduced Chemotaxis: burns, diabetes, cancer Reduced Phagocytosis: diabetes, complement deficiency, immunoglobulin deficiency, genetic defect in phagocytes Age: very young or very old
  25. 25. Staphylococcus aureus Pyodermas Impetigo - crusting vesicle formation of the skin Folliculitis - hair follicles infected Furnuncles - boil Carbuncle - multiple skin lesions connected by sinuses in the connective tissue Paronychia - infection of the nail bed Cellulitis - spreading connective tissue infection Eye Infections -
  26. 26. Staphylococcus aureus: Bulbus Impetigo
  27. 27. Staphylococcus aureus: Bulbous Impetigo
  28. 28. Staphylococcus aureus: Pustular Impetigo
  29. 29. Folliculitis • Superficial folliculitis • Infection of hair follicles • Commonly caused by staph. aureus • Children • Scalp & limb • Rarely painful • Heals in a week
  30. 30. Photo of Arm Showing Folliculitis
  31. 31. Folliculitis Caused by Staphylococcus aureus
  32. 32. Staphylococcus aureus: Folliculitis
  33. 33. Furuncle (Boil) • Acute • Staph. aureus • Small, follicular noduler -- Pustule-necrotic--discharge pus • Painful • Constitutional symptoms ‫میگذارند‬ ‫علئمی که روی تمام بدن تاثیر‬
  34. 34. Furuncle Caused by Staphylococcus aureus
  35. 35. Furuncle (Boil) Caused by Staphylococcus aureus
  36. 36. Staphylococcus aureus: Furuncle on Back of Neck
  37. 37. Carbuncle • Extensive infection of a group of contagious follicles • Staph. aureus • Middle or old age • Predisposing factors – Diabetes – Malnutrition – During prolonged steroid therapy
  38. 38. • Painful, hard lump • Suppuration begins after 5-7 days • Pus discharge from multiple follicular orificies • Large deep ulcer
  39. 39. Staphylococcus aureus: Carbuncle on Chin
  40. 40. Staphylococcus aureus: paryonchia Pus
  41. 41. Blepharitis Caused by Staphylococcus aureus
  42. 42. Staphylococcus aureus: Leading Cause of Blepharitis
  43. 43. Keratitis Caused by Staphylococcus aureus
  44. 44. Staphylococcus aureus: Keratitis
  45. 45. Systemic Infections • 1. With obvious focus – Osteomyelitis, arthritis • 2. No obvious focus • heart (infective endocarditis) • Brain(brain abscesses)
  46. 46. Staphylococcus aureus: Osteomyelitis L2 L3 Day 0 = No changes Day 35 = destruction of L2 ( , ), exotoses of L2 & L3 ( ), compression ( )
  47. 47. B. TOXIN MEDIATED DISEASES • 1. Staphylococcal food poisoning – – – – Due to production of entero toxins (A-F, G-I, K-M) SEB (super Ag) heat stable entero toxin acts on gut produces severe vomiting following a very short incubation period – Resolves on its own within about 24 hours
  48. 48. Causes of Food Poisoning - - circa 1980 Parasitic Viral Chemical UNKNOWN Other C. botulinum Shigella Salmonella Staphylococcus C. perfringens
  49. 49. 2. Toxic shock syndrome • High fever, diarrhoea,vomiting, shock and erythematous skin rash which desquamate • Mediated via ‘toxic shock syndrome toxin’ • 10% mortality rate • Described in two groups of patients – ass. With young women using tampones during menstruation – Described in young children and men
  50. 50. Staphylococcus TSST Causes Desquamation
  51. 51. Rash Associated with TSST Notice: men get toxic shock syndrome, only ~20% are due to vaginal infection
  52. 52. Erythomatous Membranes of Toxic Shock Syndrome
  53. 53. Toxic Shock Syndrome: Cutaneous and Soft Tissue Involvement Woman’s side showing extensive tissue rash due to TSST.
  54. 54. 3. Scalded skin syndrome • Disease of young children • Mediated via exfoliative toxins • Mild erythema and blistering of skin followed by shedding of sheets of epidermis • Heals 7 - 14 day • Don’t grow staph. from blister fluid
  55. 55. Staphylococcus Exfoliative Toxin Properties Exfoliative Toxin A Exfoliative Toxin B Size (Daltons) 24,000 24, 000 Temperature stable 100C labile 60οC EDTA labile stable DNA chromosome plasmid
  56. 56. Scalded Skin Syndrome Involving Exfoliative Toxin Peeling skin
  57. 57. Staphylococcus aureus: Scalded Skin Syndrome
  58. 58. Scalded-Skin Syndrome: S. aureus Exfoliative Toxin Toxin produced during rather limited infection from either plasmid or chromosomal toxin gene. This condition is typically reversible with antibiotic therapy.
  59. 59. Thanks for your attention

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