Pneumostaph45

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Pneumostaph45

  1. 1. Streptococcus pneumoniae Staphylococci Faculty: Dr. Alvin Fox www.freelivedoctor.com
  2. 2. <ul><li>S. pneumoniae </li></ul><ul><li>diplococci </li></ul><ul><li>Pneumococcus </li></ul><ul><li>autolysin </li></ul><ul><li>bile solubility test </li></ul><ul><li>optochin susceptibility </li></ul><ul><li>capsule </li></ul><ul><li>Quellung reaction </li></ul><ul><li>Staphylococcus aureus </li></ul><ul><li>opportunistic diseases </li></ul><ul><li>food poisoning/enterotoxins </li></ul><ul><li>toxic shock syndrome </li></ul><ul><li>toxic shock toxin </li></ul><ul><li>exfoliative toxin/scalded skin syndrome </li></ul><ul><li> ,  ,  ,  cytotoxins </li></ul><ul><li>leucocidin </li></ul><ul><li>lipase </li></ul><ul><li>hyaluronidase </li></ul><ul><li>protein A </li></ul><ul><li>coagulase (+) or coagulase (–) </li></ul><ul><li>Staphylococcus epidermidis </li></ul>KEYWORDS www.freelivedoctor.com
  3. 3. S. pneumoniae www.freelivedoctor.com
  4. 4. S. pneumoniae <ul><li>leading cause of pneumonia </li></ul><ul><ul><li>particularly young and old </li></ul></ul><ul><ul><li>after damage to upper respiratory tract </li></ul></ul><ul><ul><ul><li>* e.g. following viral infection </li></ul></ul></ul><ul><li>bacteremia </li></ul><ul><li>meningitis </li></ul><ul><li>middle ear infections (otitis media) </li></ul>www.freelivedoctor.com
  5. 5. S. pneumoniae <ul><li> hemolytic </li></ul><ul><li>pneumolysin </li></ul><ul><ul><li>degrades red blood cells under aerobic conditions </li></ul></ul><ul><li>grows well on sheep blood agar </li></ul><ul><li>no group antigen </li></ul>www.freelivedoctor.com
  6. 6. Diagnosis - spinal fluid <ul><li>direct Gram staining </li></ul><ul><li>detection of capsular antigen </li></ul>www.freelivedoctor.com
  7. 7. Autolysis - identification Bile peptidoglycan cell membrane lipoteichoic acid teichoic acid -choline autolysin www.freelivedoctor.com
  8. 8. C polysaccharide <ul><li>Teichoic acid </li></ul><ul><ul><li>Precipitates in serum </li></ul></ul><ul><ul><li>C-reactive protein </li></ul></ul>www.freelivedoctor.com
  9. 9. Not optochin sensitive optochin sensitive Identification www.freelivedoctor.com
  10. 10. Capsule <ul><li>prominent </li></ul><ul><ul><li>virulent strains </li></ul></ul><ul><li>anti-phagocytic </li></ul><ul><li>carbohydrate antigens </li></ul><ul><ul><li>vary among strains </li></ul></ul>www.freelivedoctor.com
  11. 11. Capsule <ul><li>immunity </li></ul><ul><ul><li>serotype specific </li></ul></ul><ul><li>vaccine contains multiple serotypes </li></ul><ul><li>only for susceptible population </li></ul>www.freelivedoctor.com
  12. 12. Quellung reaction <ul><li>using antisera </li></ul><ul><li>capsule &quot;fixed&quot; </li></ul><ul><li>visible microscopically </li></ul>www.freelivedoctor.com
  13. 13. Pathogenesis <ul><li>Teichoic acid </li></ul><ul><ul><li>complement activation </li></ul></ul><ul><ul><li>large numbers of inflammatory cells at infection site </li></ul></ul>www.freelivedoctor.com
  14. 14. Therapy <ul><li>S. pneumoniae </li></ul><ul><ul><li>most strains susceptible to penicillin </li></ul></ul><ul><ul><li>resistance is common </li></ul></ul>www.freelivedoctor.com
  15. 15. STAPHYLOCOCCI <ul><li>Gram positive </li></ul><ul><li>Facultative anaerobes </li></ul><ul><li>Grape like-clusters </li></ul><ul><li>Catalase positive </li></ul><ul><li>Major components </li></ul><ul><li>of normal flora </li></ul><ul><ul><li>skin </li></ul></ul><ul><ul><li>nose </li></ul></ul>www.freelivedoctor.com
  16. 16. Staphylococcus aureus www.freelivedoctor.com
  17. 17. One of commonest opportunistic infections - hospital and community : <ul><li>pneumonia </li></ul><ul><li>osteomyelitis </li></ul><ul><li>septic arthritis </li></ul><ul><li>bacteremia </li></ul><ul><li>endocarditis </li></ul><ul><li>abscesses/boils </li></ul><ul><li>other skin infections </li></ul>www.freelivedoctor.com
  18. 18. Food poisoning <ul><li>not an infection </li></ul><ul><li>food contaminated by humans </li></ul><ul><ul><li>growth of bacteria </li></ul></ul><ul><ul><li>production of enterotoxin </li></ul></ul><ul><li>onset and recovery both occur within few hours </li></ul>www.freelivedoctor.com
  19. 19. Food poisoning <ul><li>Vomiting </li></ul><ul><li>nausea </li></ul><ul><li>diarrhea </li></ul><ul><li>abdominal pain </li></ul>www.freelivedoctor.com
  20. 20. Toxic shock syndrome <ul><li>fever </li></ul><ul><li>rash </li></ul><ul><li>desquamation </li></ul><ul><li>vomiting </li></ul><ul><li>diarrhea </li></ul>www.freelivedoctor.com
  21. 21. Toxic shock syndrome <ul><li>Toxic shock toxin </li></ul><ul><ul><li>Dissemination </li></ul></ul><ul><li>Organism </li></ul><ul><ul><li>no dissemination </li></ul></ul>www.freelivedoctor.com
  22. 22. S. aureus <ul><li>babies </li></ul><ul><ul><li>scalded skin syndrome </li></ul></ul><ul><ul><ul><li>exfoliatin </li></ul></ul></ul>www.freelivedoctor.com
  23. 23. Lytic exotoxins: <ul><li> toxin </li></ul><ul><li> (sphingomyelinase C) </li></ul><ul><li> toxin </li></ul><ul><li> toxins </li></ul><ul><ul><li>detergent-like </li></ul></ul><ul><li>leucocidins </li></ul>www.freelivedoctor.com
  24. 24. Protein A inhibits phagocytosis Protein A immunoglobulin Fc receptor BACTERIUM PHAGOCYTE www.freelivedoctor.com
  25. 25. Spread <ul><li>tissue-degrading enzymes </li></ul><ul><ul><li>lipase </li></ul></ul><ul><ul><li>hyaluronidase </li></ul></ul>www.freelivedoctor.com
  26. 26. Identification <ul><li> hemolytic </li></ul><ul><li>sheep blood agar </li></ul><ul><li>yellow pigmented (aureus) </li></ul><ul><li>mannitol fermentation </li></ul><ul><li>coagulase-positive </li></ul><ul><li>reference laboratories </li></ul><ul><li>phage-typing </li></ul>www.freelivedoctor.com
  27. 27. Staphylococcus epidermidis <ul><li>major component, skin flora </li></ul><ul><li>opportunistic infection </li></ul><ul><li>- less common than S.aureus </li></ul><ul><li>nosomial infections </li></ul><ul><ul><li>shunts, catheters </li></ul></ul><ul><li>artificial heart valves/joints </li></ul>www.freelivedoctor.com
  28. 28. Identification <ul><li>Non-hemolytic </li></ul><ul><ul><li>sheep blood agar </li></ul></ul><ul><ul><li>Non-pigmented </li></ul></ul><ul><li>Does not ferment mannitol </li></ul><ul><li>Coagulase negative </li></ul>www.freelivedoctor.com
  29. 29. Staphylococcus saprophyticus <ul><li>urinary tract infections </li></ul><ul><li>coagulase-negative </li></ul><ul><ul><li>not usually differentiated from S. epidermidis </li></ul></ul>www.freelivedoctor.com
  30. 30. Antibiotic therapy <ul><li>Resistance to penicillin </li></ul><ul><ul><li>penicillinase </li></ul></ul><ul><li> lactam antibiotics (including methicillin [MRSA]) </li></ul><ul><ul><li>often ineffective </li></ul></ul><ul><ul><li>modified penicillin binding proteins </li></ul></ul><ul><li>Vancomycin </li></ul><ul><ul><li>current drug of choice </li></ul></ul><ul><ul><li>resistance has been observed </li></ul></ul>www.freelivedoctor.com
  31. 31. GRAM POSITIVE COCCI S. aureus  hemolytic mannitol yellow + - Staphylococcus (Clusters) Streptococcus (pairs & chains) Catalase BETA: Bacitracin S. pyogenes (group A) CAMP/ Hippurate S. agalactiae (group B) Hemolysis Coagulase S. epidermidis nonhemolytic (usually) mannitol white ALPHA: Optochin /Bile Solubility S. pneumoniae GAMMA: Bile Esculin 6.5% NaCl Group D* Enterococcus Bile Esculin 6.5% NaCl Group D* Non- Enterococcus (*can also be alpha hemolytic) Note: S. viridans is Is alpha hemolytic and negative for all the tests below below + + + + + + + - - Summary Figure (Identification Scheme) www.freelivedoctor.com

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