Ok  s. aureus  mehre 92
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Ok s. aureus mehre 92

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

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

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Ok  s. aureus  mehre 92 Ok s. aureus mehre 92 Presentation Transcript

  • STAPHYLOCOCCI
  • STAPHYLOCOCCUS • • • • • • • • Introduction Classification Antigenic Structure Staphylococcal Enzymes Staphylococcal Toxins Pathogenesis Resistance to antibiotics Treatment
  • Staphylococcus • • • • • • F. Micrococcaceae G. Staphylococcus G. Micrococcus G. Stomatococcus G. Planococcus (facultative anaerobic) (only aerobic) (facultative anaerobic) (only aerobic)
  • 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
  • Gram Stain of Staphylococcus Culture Gram-positive cocci predominately in clusters
  • Spread of Hospital Strain of Staphylococcus aureus Nurse (Carrier) Doctor: Boil Salesman: Carrier and Paronychia Son: Impetig o
  • 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
  • Grouping for Clinical Purposes • 1. Coagulase positive Staphylococci – Staphylococcus aureus • 2. Coagulase negative Staphylococci – Staphylococcus epidermidis – Staphylococcus saprophyticus
  • 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
  • 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.
  • 3. Stapylococcus saprophyticus • Skin commensal • Imp. Cause of UTI in sexually active young women • UTI in men (usually after age 50) • Cystitis, pyelonephritis
  • 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 )
  • • 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
  • Antigenic structure • • • • Capsule Peptidoglycan Teichoic acid Protein A
  • Staphylococcus Structural Virulence Factors = peptidoglycan = capsule = PNSG (biofilm) = clumping factor = fibronectin binding protein = protein A = collagen binding protein = teichoic acid
  • Structural Carbohydrates and Virulence Peptidoglycan Inflammatory Teichoic Acid Inflammatory & allergen Capsule* Anti-phagocytic PNSG* Biofilm * - Antibodies to these carbohydrates are protective
  • 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
  • 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
  • Staphylococcal Enzymes • • • • • • • Coagulase Catalase Hyaluronidase Fibrinolysine Lipases Nucleases Penicillinase
  • 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)
  • α , β ,γ -hemolysin • • • • Toxic for : leukocytes , erythrocytes, macrophages and platelets Lymphocytes
  • 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
  • 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
  • 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
  • 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 -
  • Staphylococcus aureus: Bulbus Impetigo
  • Staphylococcus aureus: Bulbous Impetigo
  • Staphylococcus aureus: Pustular Impetigo
  • Folliculitis • Superficial folliculitis • Infection of hair follicles • Commonly caused by staph. aureus • Children • Scalp & limb • Rarely painful • Heals in a week
  • Photo of Arm Showing Folliculitis
  • Folliculitis Caused by Staphylococcus aureus
  • Staphylococcus aureus: Folliculitis
  • Furuncle (Boil) • Acute • Staph. aureus • Small, follicular noduler -- Pustule-necrotic--discharge pus • Painful • Constitutional symptoms ‫میگذارند‬ ‫علئمی که روی تمام بدن تاثیر‬
  • Furuncle Caused by Staphylococcus aureus
  • Furuncle (Boil) Caused by Staphylococcus aureus
  • Staphylococcus aureus: Furuncle on Back of Neck
  • Carbuncle • Extensive infection of a group of contagious follicles • Staph. aureus • Middle or old age • Predisposing factors – Diabetes – Malnutrition – During prolonged steroid therapy
  • • Painful, hard lump • Suppuration begins after 5-7 days • Pus discharge from multiple follicular orificies • Large deep ulcer
  • Staphylococcus aureus: Carbuncle on Chin
  • Staphylococcus aureus: paryonchia Pus
  • Blepharitis Caused by Staphylococcus aureus
  • Staphylococcus aureus: Leading Cause of Blepharitis
  • Keratitis Caused by Staphylococcus aureus
  • Staphylococcus aureus: Keratitis
  • Systemic Infections • 1. With obvious focus – Osteomyelitis, arthritis • 2. No obvious focus • heart (infective endocarditis) • Brain(brain abscesses)
  • Staphylococcus aureus: Osteomyelitis L2 L3 Day 0 = No changes Day 35 = destruction of L2 ( , ), exotoses of L2 & L3 ( ), compression ( )
  • 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
  • Causes of Food Poisoning - - circa 1980 Parasitic Viral Chemical UNKNOWN Other C. botulinum Shigella Salmonella Staphylococcus C. perfringens
  • 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
  • Staphylococcus TSST Causes Desquamation
  • Rash Associated with TSST Notice: men get toxic shock syndrome, only ~20% are due to vaginal infection
  • Erythomatous Membranes of Toxic Shock Syndrome
  • Toxic Shock Syndrome: Cutaneous and Soft Tissue Involvement Woman’s side showing extensive tissue rash due to TSST.
  • 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
  • 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
  • Scalded Skin Syndrome Involving Exfoliative Toxin Peeling skin
  • Staphylococcus aureus: Scalded Skin Syndrome
  • 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.
  • Thanks for your attention