Lecture pp5&6staphylococcus

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  • Clockwise from Top Left Staphylococcal Scalded Skin Syndrome (SSSS) Bullous impetigo (localized form of SSSS) Pustular impetigo Septic embolization Toxic Shock Syndrome (TSS)
  • Lecture pp5&6staphylococcus

    1. 1. Staphylococcus
    2. 2. Classification • Family • Genus • Species Micrococcaceae Micrococcus and Staphylococcus S. aureus S. saprophyticus S. epidermidis M. luteusmore than 20 specie s
    3. 3. Gram-Positive Cocci Enterococcus (Group D CHO) γ hemolytic (α or β) Enterococcus faecalis, E. faecium FAMILY Micrococcaceae (catalase positive) Coagulase-positive Staphylococcus aureus Coag.-neg. Staphylococcus epidermidis, S. saprophyticus FAMILY Streptococcaceae (catalase negative) Group A: β-hemolytic Streptococcus pyogenes Group B: β-hemolytic (occasionally α or γ) S. agalactiae Group C: β-hemolytic (α or γ) S. anginosus, S. equismilis Group D: α or γ hemolytic (β) S. bovis Group F: β-hemolytic S. anginosus Group G: β -hemolytic S. anginosus Viridans streptococci: (no group specific CHO) α or γ hemolytic S. mutans and S. salivarius, S. sanguis, S. mitis and S. milleri groups Streptococcus pneumoniae (no group CHO)(α-hemolytic)
    4. 4. Morphology
    5. 5. Morphology Staph vs. Strep Gram-positive cocci in clusters
    6. 6. StreptococcusStaphylococcus
    7. 7. Staphylococcus
    8. 8. See Overheads ~~~~~~~~~~ TSS Foodborne Intoxication ~~~~~~~~~~
    9. 9. MICROBIAL PATHOGEN ADHESIN RECEPTOR Staphylococcus aureus LLiippootteeiicchhooiicc aacciidd Unknown Staphylococcus spp. SSlliimmee llaayyeerr Unknown Group A Streptococcus LLTTAA--MM pprrootteeiinn ccoommpplleexx FFiibbrroonneeccttiinn Streptococcus pneumoniae Protein N-acetylhexosamine-gal Escherichia coli Type 1 fimbriae CFA 1 fimbriae P fimbriae D-MMaannnnoossee GM ggaanngglliioossiiddee P blood grp glycolipid Other Enterobacteriaceae Type 1 fimbriae D-Mannose Neisseria gonorrhoeae Fimbriae GD1 ganglioside Treponema pallidum P1, P2, P3 Fibronectin Chlamydia spp. Cell surface lectin N-acetylglucosamine Mycoplasma pneumoniae Protein P1 Sialic acid Vibrio cholerae Type 4 pili Fucose and mannose
    10. 10. Cell-Associated Virulence Factors • Capsule or slime layer (glycocalyx) • Peptidoglycan (PG) • Teichoic acid is covalently linked to PG and is species specific: S. aureus ribitol teichoic acid (polysaccharide A) S. epidermidis glycerol teichoic acid (polysaccharide B) • Protein A is covalently linked to PG • Clumping factor (bound coagulase)
    11. 11. Virulence Factors Extracellular Enzymes • Coagulases (bound or free) Antigenic • Hyaluronidase “spreading factor” of S. aureus • Nuclease Cleaves DNA and RNA in S. aureus • Protease Staphylokinase (fibrinolysin) • Lipases • Esterases
    12. 12. Virulence Factors: Exotoxins • Cytolytic (cytotoxins; cytolysins)  Alpha toxin - hemolysin • Reacts with RBCs  Beta toxin • Sphingomyelinase  Gamma toxin • Hemolytic activity  Delta toxin • Cytopathic for: – RBCs – Macrophages – Lymphocytes – Neutrophils – Platelets • Enterotoxic activity  Leukocidin
    13. 13. • Enterotoxin • Exfoliative toxin (epidermolytic toxin) • Pyrogenic exotoxins Virulence Factors: Exotoxins
    14. 14. Pathogenesis • Pass skin – first line of defense  Benign infection • Phagocytosis • Antibody • Inflammatory response Chronic infections • Delayed hypersensitivity
    15. 15. Clinical Manifestations/Disease • SKIN  folliculitis  boils (furuncles)  carbuncles  impetigo (bullous & pustular)  scalded skin syndrome •Neonates and children under 4 years
    16. 16. Clinical Manifestations/Disease • Other infections  Primary staphylococcal pneumonia  Food poisoning vs. foodborne disease  Toxic shock syndrome
    17. 17. Metastatic Infections •Bacteremia •Osteomyelitis disease of growing bone • Pulmonary and cardiovascular infection
    18. 18. Coagulase-Negative Staphylococci • Staphylococcus epidermidis • S. saprophyticus
    19. 19. Staphylococcal Lab ID & Diagnostic Tests • Microscopic • Lab isolation • Coagulase positive  S. aureus
    20. 20. Mannitol Salts Agar (MSA) Staphylococcus aureus
    21. 21. Catalase 2H2O2  O2 + 2H2O Streptococci vs. Staphylococci Differential Characteristics
    22. 22. Catalase POS Staphylococcus Catalase NEG
    23. 23. S. aureus Coagulase Fibrinogen  Fibrin Differential Characteristics
    24. 24. Coagulase NEG Coagulase POS Staphylococcus aureus
    25. 25. Treatment • Drain infected area • Deep/metastatic infections  semi-synthetic penicllins  cephalosporins  erythromycin  clindamycin • Endocarditis  semi-synthetic penicillin + an aminoglycoside
    26. 26. Prevention • Carrier status prevents complete control • Proper hygiene, segregation of carrier from highly susceptible individuals • Good aseptic techniques when handling surgical instruments • Control of nosocomial infections
    27. 27. REVIEW
    28. 28. Gram-Positive Cocci Enterococcus (Group D CHO) γ hemolytic (α or β) Enterococcus faecalis, E. faecium FAMILY Micrococcaceae (catalase positive) Coagulase-positive Staphylococcus aureus Coag.-neg. Staphylococcus epidermidis, S. saprophyticus FAMILY Streptococcaceae (catalase negative) Group A: β-hemolytic Streptococcus pyogenes Group B: β-hemolytic (occasionally α or γ) S. agalactiae Group C: β-hemolytic (α or γ) S. anginosus, S. equismilis Group D: α or γ hemolytic (β) S. bovis Group F: β-hemolytic S. anginosus Group G: β -hemolytic S. anginosus Viridans streptococci: (no group specific CHO) α or γ hemolytic S. mutans and S. salivarius, S. sanguis, S. mitis and S. milleri groups Streptococcus pneumoniae (no group CHO)(α-hemolytic) REVIEW
    29. 29. REVIEW Which features are only found in S. aureus? S. epidermidis S. aureus
    30. 30. REVIEW
    31. 31. REVIEW
    32. 32. REVIEW
    33. 33. REVIEW
    34. 34. REVIEW

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