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Staphylococcus

Staphylococcus. Hugh B. Fackrell Filename: staph.ppt. Outline. Definition Extracellular products Diseases suppuration intoxications. Staphylococcus. Gram +ve cocci in clusters catalase +ve facultative anaerobes sensitive to lysostaphin endopeptidase resistant to lysozyme

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Staphylococcus

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  1. Staphylococcus Hugh B. Fackrell Filename:staph.ppt

  2. Outline • Definition • Extracellular products • Diseases • suppuration • intoxications

  3. Staphylococcus • Gram +ve cocci in clusters • catalase +ve facultative anaerobes • sensitive to lysostaphin endopeptidase • resistant to lysozyme • ribitol or glyercol teichoic acids

  4. Staphylococcus: structure • Gram positive spheres in grape-like clusters • Staphylo= grapes • Coccus = spheres

  5. TOXINS Hemolysins Leucocidin ( Leukocidin) Enterotoxins Exfoliative toxins TSS toxin ENZYMES DNAse Coagulase Fibrinolysin Lipases Hyaluronidase Extracellular Products of Staphylococci

  6. Staphylococcus aureus produces the enzyme Endonuclease

  7. Staphlylococcal Coagulase • Coagulase: enzymes that cause clotting of blood plasma • Measured by • tube test (Free coagulase) • slide test (Bound coagulase) • Differentiation of Staphylococcal pathogens • S.aureus coagulase positive

  8. Coagulase vs FibrinolysinCompeting Enzymes • Coagulase: forms clots • Fibrinolysin: dissolves clots • Staphylococcus produces coagulase early • protection against phagocytosis • When cell numbers high make fibrolysin • break out of protection

  9. Resistant to bile salts • Most strains grow in the presence of 40% bile salts • colonize intestine • Most strains grown the presence of 15% NaCl • Colonize the skin

  10. Major Staphylococcal Pathogens • Staphylococcus aureus • infections & intoxications • Staphylococcus epidermidis • “stitch abcesses” • Staphylococcus saprophyticus • urinary tract infections

  11. Staphylococci are NOT highly invasive • S aureus:50% are carriers • found in nose area • S. epidermidis: universal • present on skin • 95% have immunity to Staphylococci

  12. Predisposing factors • Break in the skin • operations, burns, abrasions • blockage of sweat glands • Chronic diseases • cancer, diabetes, cirrhosis • Staphylococcal pneumonia

  13. Staphylococcal diseases • Suppurative Diseases • pus • infiltration of WBC of polymorphonuclear leucocytes • Toxic poisonings

  14. Staphylococcal Suppurative Diseases • boils, furuncles, carbuncles • wound infections • deep tissue abcesses • osteomyelitis • pneumonia, empyema • (intrapleural abcesses) • endocarditis, pericarditis • meningitis • purulent arthritis

  15. Staphylococcal mastitis • Udder infections in dairy cattle • Penicillin resistant Staphylococci • Before antibiotics • Streptococcus group B & Group C

  16. Deep Tissue Abcesses • Often resist antibiotics • Surgical intervention • Drainage • Antitoxins

  17. Staphylococcal Intoxications • Enterotoxin • food poisoning • Toxic shock syndrome • Hemolysins • Epidermolytic toxin • “scalded skin syndrome” • Leucocidin

  18. Staphylococcal Hemolysins • Discovered because they Destroy RBCs • 4 types • alpha: lethal cardiovascular • beta: “ hot cold” sphingomyelinase • aggregates platelets • gamma: slightly dermonecrotic • lethal in rabbits • delta: bee venom

  19. Platelet Damage by Toxins

  20. Staphylococcal Food Poisoning • Secreted protein • produced at room temp • produced aerobically and anaerobically • milk & meat products excellent media • Food handlers - carriers

  21. Staphlylococcal Food Poisoning Signs & Symptoms • Symptoms • Nausea • Abdominal pain • Projectile vomiting • Diarrhea • Onset: average 3 hours • 1-6 hours • Duration: 24 hours

  22. Enterotoxin • Several different forms • Protein 24,000 MW • Resistant to • acids • proteases in digestive tract • boiling for 2 hours • Gene carried by lysogenic phage

  23. Toxic Shock Syndrome • First reported 1980 • young women during menstruation • tampons containing methacrylate supported growth of S. aureus and production of toxin • Shock & death

  24. The End

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