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Staph and Strep

Staph and Strep. Cocci Morphology. Catalase Test. Enzyme Catalase (+) bubbles Staphylococcus (-) no bubbles Streptococcus Enterococcus Detoxify hydrogen peroxide H2O2  H2O + O2. Columbia - CNA. Selective for GP Colistin Nalidixic Acid Differential Blood hemolysis.

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Staph and Strep

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  1. Staph and Strep

  2. Cocci Morphology

  3. Catalase Test • Enzyme • Catalase • (+) bubbles • Staphylococcus • (-) no bubbles • Streptococcus • Enterococcus • Detoxify hydrogen peroxide • H2O2  H2O + O2

  4. Columbia - CNA • Selective for GP • Colistin • Nalidixic Acid • Differential • Blood hemolysis

  5. BAP: Hemolysis Gamma Alpha

  6. BAP Hemolysis: Beta

  7. Gram Stain: Staph

  8. MSA • Selective • 7.5 % NaCl, halotolerant • Staphylococci • Differential • pH indicator: phenol red • Mannitol • Fermentation • Acid end products • Yellow • Non fermentation = red

  9. MSA

  10. DNase • Differential • Dye • Methyl green • pH 7.5 • Enzyme • hydrolytic • DNase • Results • Clear zone = (+)

  11. Mueller-Hinton Agar (MH) • AB sensitivity • Novobiocin Disc • Sensitive > 18 mm • Resistant < 18 mm • Staph chart for ID

  12. Staph Tri-plates • Mannitol • Growth • NF • DNAse (+) • Novobiocin (S)

  13. Staph Tri-Plates • Mannitol • Growth • Fermentation • DNAse (+) • Novobiocin (S)

  14. Staph Tri-plate • Mannitol • Growth • NF • DNAse (-) • Novobiocin (R)

  15. Staph Tri-plate • Mannitol • Growth • Fermentation • DNAse (-) • Novobiocin (R)

  16. Coagulase Test • Staph aureus • Converts fibrinogen to fibrin • Immune defense • Protection from phagocytosis

  17. Rapid Staph Test • Staph aureus • Virulence Factors • Coagulase (+) • Fibrinogen  Fibrin • Clots • Protein A • Fc regions of IgG • Inhibits Ab • Results • Color Change • Clumping

  18. Anaerobic Systems • Facultative Anaerobes • Staph • Capnophiles • Strep

  19. Streptococcus • GP cocci • Chains • Catalase (-) • Capnophiles • Groups • Lancefield Groups • Surface Antigens

  20. Lancefield Strep Classifications • Group A • S. pyogenes • Group B • S agalactia • Group C • S. equi • Group D • Enterococcus faecalis • S. bovis • Group K • S. salivarius • Viridans • S. mutans • S. mitis • Pneumoocci • S. pneumoniae

  21. Catalase and MSA • Catalase (-) • MSA • No growth • Not halotolerant • Except • Enterococcus (-)

  22. Hemolysis Types

  23. Bacitracin and SXT Sensitivities

  24. Zone of Inhibition

  25. Ab Sensitivities • Bacitracin • Any zone = Sensitive • No clearing = Resistant • SXT • Zone > 20 mm = S • Zone < 20 mm = R

  26. Bile Esculin • Selective • Bile salts • Enteric organism growth • Differential • Hydrolyze esculin (CH2O) • Reacts with FeNH3-citrate • Results • Growth • Black precipitate

  27. CAMP Identify Group B Strep (GBS) CAMP factor enhances hemolysis Arrow Head produced for GBS

  28. Rapid Strep Test • Group A Strep • Immunoassay • Ag ID • Ab on test strip • Results • Color change

  29. Flow Chart

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