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Lecture pp5&6staphylococcus

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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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