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A Brief Class on Staphylococcus

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  1. 1. STAPHYLOCOCCUS Gram positive cocci arranged in grape like clusters Commonest cause of localized suppurative lesions in humans Habitat includes skin ,hair,anterior nasal area Imp sps- S.aureus, S.epidermidis,S.saprophyticus etc
  2. 2. Staphylococcus aureusMORPHOLOGY Gram poitive ,Arranged in grape like clusters,Non motile, Non sporing, Non capsulated 1 micrometer in diameter
  4. 4. CULTURAL CHARACTERS Grow readly on ordinary media Temp range-10-42 degree Celsius, Optimum-37 Ph-7.4-7.6 They are aerobes and facultative anaerobes Common media are Nutrient agar & Blood agar
  5. 5. On Nutrient agar 2-4mm diameter colony.circular ,smooth ,convex ,Most strains produce golden yellow pigment
  6. 6. Colonies of staphylococcus aureus
  7. 7. On Blood agar Produce beta hemolytic colonies
  8. 8. Colonies of staphylococcus albus
  9. 9. Colonies of staphylococcus cetreus
  10. 10. Colonies on biood agar
  11. 11.  Selectivemedia is Mannitol salt agar Produce yellow colonies on mannitol salt agar
  12. 12. Selective media-mannitol salt agar
  13. 13. Biochemical propertis Catalase + Oxidase – Coagulase +
  14. 14. Following properties are imp todistigush S.aureus from other nonpathogenic sps Coagulase production Mannilol fermentation Golden yellow pigment Liquefy gelatin Phosphatase production DNase production
  15. 15. ANTIGENIC STRUCTURE &VIRULANCE FACTORSANTIGENIC STRUCTURECapsule Some strains have a capsule. That inhibit phagocytosis, they inhibit opsonisation Capsulated strains are more virulentPeptidoglycan Give rigidity to the cell wall, activtes complimentTeichoic acid Major antigenic component Protect cell from compliment mediated opsonisationProtein A It has chemotactic,antiphagocytic & anti complimentary action
  16. 16. TOXINS & ENZYMESStaph aureus produce a number of toxins & extra cellular enzymesTOXINS1. Cytolytic toxin2. Entero toxin3. Toxic shock syndrome toxin4. Exfoliative(epidrmolytic toxin)
  17. 17. CYTOLYTIC TOXIN2 Types HEMOLYSIN & LEUCOCIDINSHEMOLYSIN Lyse RBCs 4 types ie, alpha, beta ,gamma & deltaLEUCOCIDINS Damage polymorphonuclear lecocytes
  18. 18. ENTERO TOXIN Responsible for staphylococcal food poisoning Nosiea,vomitting & diarrhea in 2-6 hrs after consumption of contaminated food Meat ,fish ,milk & milks products are the main foods responsible for this condition Source of infection is a food handler who is a carrier.
  19. 19. TOXIC SHOCK SYNDROMETOXIN Causing toxic shock syndrome It is a fatal multi system disease with fever ,hypotension,myalgia,vomitting, diarrhea, erythematous rashes etc It is potentially a a fatal diasease
  20. 20. Exfoliative (epidermolytic)toxin Responsible for staphylococcal scaled skin disease Here the outer layer of epidermis gets separated from the underlying tissue
  21. 21. ENZYMESCOAGULASE It is the most important enzyme which brings the clotting of human or rabbit plasma 2 types of coagulase engyme- Bound coagulase-which is bound to the cell wall Free coagulase-which is liberated free in to the surrounding medium This enzyme can be demonstrated by COAGULASE TEST Coagulase test is the standard criteria for the identification of Staph aureus SLIDE Test (For bound coagulase) & TUBE Test(for free coagulase) are there
  22. 22. Other enzymes Lipases Hyaluronidase Nuclease
  23. 23. STAPHYLOCOCCAL DISEASESSkin & soft tissue infections Folliculitis Furancles(boils) Wound infections Brest abscess Carbuncles Cellulitis Styes
  24. 24. CARBUNCLES
  25. 25. Multiple carbuncles
  26. 26. Abscess
  27. 27. Wound infection
  28. 28. cellulitis
  29. 29. faurancles
  30. 30. boils
  31. 31. styes
  32. 32. Brest abscess
  33. 33. impetigo
  34. 34. MUSCULOSKELETALINFECTIONS Osteomyelitis Arthritis etc
  35. 35. osteomyaliytis
  36. 36. RESPIRATORY INFECTIONS Tonsillitis Pharyngitis Sinusitis Otis Broncho npneumonia Lung abscess Empyemia
  37. 37. Lung abscess
  38. 38. tonsillitis
  39. 39. CNS INFECTIONS Brainabscess Meningitis etc
  40. 40. meningitis
  41. 41. Endo vascular infections Bacteremia Septicemia Pyemia EndocarditisURINARY INFECTIONS Staph are uncommon in UTI, but may cause infections in association with lacal instrumentation, implants or diabetes
  43. 43. Food poisoning
  44. 44. Toxic shock syndrome
  45. 45. Scaled skin disease
  46. 46. Staphylococcal infections
  47. 47. LAB DIAGNOSISSPECIMENSSpecimens are to be depend on the type of lesions1. Pus(suppurative lesions)2. Sputum(respiratory infections)3. Blood(endo vascular)4. CSF(CNS infections)5. Urine (UTI)6. Feces,vomit,remains of suspected food(food poisoning)7. Nasal swab(carriers)
  48. 48. METHODSDirect microscopySmears of material shows gram positive cocci in clustersCultureInoculated on to BLOOD AGAR ,NUTRIENT AGAR etcLook for typical colony morphology,hemolysis,pigmentation etc
  49. 49. BICHEMICHAL REACTIONS Catalase - positive Oxidase - negative Coagulase -positive DNase -positive Phosphatase - positive Mannitiol fermentation -positve
  50. 50. COAGULASE TEST Itis the main lab test used to differenciate staph aureus from other sps of 2 types –slide test & tube testSlide coagulase testFew colonies are emulsified in a drop of normal saline on a slide and mixed with a drop of rabbit or human plasma.Clumping indicates positive reaction
  51. 51. Slide coagulase test
  52. 52. TUBE COAGULASE test Done to detect free coagulase 0.1 ml broth culture of the isolate is added to 0.5 ml of human or rabbit plasma in a narrow test tube. The tubes incubated at 37 degree Celsius for 3-6 hrs If positive ,the plasma clots & does not flow when the tube is tilted
  53. 53. Tube coagulase test
  54. 54. Mannitol fermentation
  55. 55. tretment Benzyl penicillin is most effective Methicillin ,cloxacillin etc can be used in penicillinase producing strainsMRSA(Methicillin resistant staph aureus)They are causing grate problem to cliniciansThey are resistant to penicillins & other beta lactam antibioticsThey can be treated by vancomycin &teicoplaninTreatment of carriers by local application of antibiotics like as bacitracin