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Staphylococcus

Staphylococcus. Classification. Family Genus Species. Micrococcaceae. Micrococcus and Staphylococcus. S. aureus S. saprophyticus S. epidermidis M. luteus. more than 20 species. Gram-Positive Cocci. FAMILY Streptococcaceae (catalase negative).

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Staphylococcus

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  1. Staphylococcus

  2. Classification • Family • Genus • Species Micrococcaceae Micrococcus and Staphylococcus S. aureus S. saprophyticus S. epidermidis M. luteus more than 20 species

  3. Gram-Positive Cocci FAMILYStreptococcaceae(catalasenegative) • GroupA:-hemolytic Streptococcuspyogenes • GroupB:-hemolytic (occasionallyor)S.agalactiae • GroupC:-hemolytic ( or) S.anginosus,S.equismilis • GroupD: or hemolytic ()S.bovis • GroupF:-hemolyticS.anginosus • GroupG:  -hemolyticS.anginosus • Viridansstreptococci:(nogroupspecificCHO) • orhemolyticS.mutans and • S.salivarius,S.sanguis,S.mitis andS.millerigroups • Streptococcuspneumoniae(nogroupCHO)(-hemolytic) • Enterococcus(GroupD CHO)hemolytic (or) • Enterococcusfaecalis,E.faecium • FAMILYMicrococcaceae(catalase positive) • Coagulase-positiveStaphylococcusaureus • Coag.-neg. Staphylococcusepidermidis, S.saprophyticus

  4. Morphology

  5. Morphology Staph vs. Strep Gram-positive cocci in clusters

  6. Staphylococcus Streptococcus

  7. Staphylococcus

  8. See Overheads ~~~~~~~~~~ TSS Foodborne Intoxication ~~~~~~~~~~

  9. 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)

  10. 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

  11. 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

  12. Virulence Factors: Exotoxins • Enterotoxin • Exfoliative toxin (epidermolytic toxin) • Pyrogenic exotoxins

  13. Pathogenesis • Pass skin – first line of defense • Benign infection • Phagocytosis • Antibody • Inflammatory response • Chronic infections • Delayed hypersensitivity

  14. Clinical Manifestations/Disease • SKIN • folliculitis • boils (furuncles) • carbuncles • impetigo (bullous & pustular) • scalded skin syndrome • Neonates and children under 4 years

  15. Clinical Manifestations/Disease • Other infections • Primary staphylococcal pneumonia • Food poisoning vs. foodborne disease • Toxic shock syndrome

  16. Metastatic Infections • Pulmonary and cardiovascular infection • Bacteremia • Osteomyelitis • disease of growing bone

  17. Coagulase-Negative Staphylococci • Staphylococcus epidermidis • S. saprophyticus

  18. Staphylococcal Lab ID & Diagnostic Tests • Microscopic • Lab isolation • Coagulase positive • S. aureus

  19. Mannitol Salts Agar (MSA) Staphylococcus aureus

  20. Differential Characteristics Catalase 2H2O2 O2 + 2H2O Streptococcivs. Staphylococci

  21. Catalase POS Catalase NEG Staphylococcus

  22. S. aureus Differential Characteristics Coagulase Fibrinogen  Fibrin

  23. Staphylococcus aureus Coagulase POS Coagulase NEG

  24. Treatment • Drain infected area • Deep/metastatic infections • semi-synthetic penicllins • cephalosporins • erythromycin • clindamycin • Endocarditis • semi-synthetic penicillin + an aminoglycoside

  25. 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

  26. REVIEW

  27. Gram-Positive Cocci FAMILYStreptococcaceae(catalasenegative) • GroupA:-hemolytic Streptococcuspyogenes • GroupB:-hemolytic (occasionallyor)S.agalactiae • GroupC:-hemolytic ( or) S.anginosus,S.equismilis • GroupD: or hemolytic ()S.bovis • GroupF:-hemolyticS.anginosus • GroupG:  -hemolyticS.anginosus • Viridansstreptococci:(nogroupspecificCHO) • orhemolyticS.mutans and • S.salivarius,S.sanguis,S.mitis andS.millerigroups • Streptococcuspneumoniae(nogroupCHO)(-hemolytic) • Enterococcus(GroupD CHO)hemolytic (or) • Enterococcusfaecalis,E.faecium • FAMILYMicrococcaceae(catalase positive) • Coagulase-positiveStaphylococcusaureus • Coag.-neg. Staphylococcusepidermidis, S.saprophyticus REVIEW

  28. Which features are only found in S. aureus? S. aureus S. epidermidis REVIEW

  29. REVIEW

  30. REVIEW

  31. REVIEW

  32. REVIEW

  33. REVIEW

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