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A Brief Class on Staphylococcus

A Brief Class on Staphylococcus

Published in: Health & Medicine

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  • 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. Staphylococcus aureusMORPHOLOGY Gram poitive ,Arranged in grape like clusters,Non motile, Non sporing, Non capsulated 1 micrometer in diameter
  • 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. On Nutrient agar 2-4mm diameter colony.circular ,smooth ,convex ,Most strains produce golden yellow pigment
  • 6. Colonies of staphylococcus aureus
  • 7. On Blood agar Produce beta hemolytic colonies
  • 8. Colonies of staphylococcus albus
  • 9. Colonies of staphylococcus cetreus
  • 10. Colonies on biood agar
  • 11.  Selectivemedia is Mannitol salt agar Produce yellow colonies on mannitol salt agar
  • 12. Selective media-mannitol salt agar
  • 13. Biochemical propertis Catalase + Oxidase – Coagulase +
  • 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. 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. TOXINS & ENZYMESStaph aureus produce a number of toxins & extra cellular enzymesTOXINS1. Cytolytic toxin2. Entero toxin3. Toxic shock syndrome toxin4. Exfoliative(epidrmolytic toxin)
  • 17. CYTOLYTIC TOXIN2 Types HEMOLYSIN & LEUCOCIDINSHEMOLYSIN Lyse RBCs 4 types ie, alpha, beta ,gamma & deltaLEUCOCIDINS Damage polymorphonuclear lecocytes
  • 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. 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. Exfoliative (epidermolytic)toxin Responsible for staphylococcal scaled skin disease Here the outer layer of epidermis gets separated from the underlying tissue
  • 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. Other enzymes Lipases Hyaluronidase Nuclease
  • 23. STAPHYLOCOCCAL DISEASESSkin & soft tissue infections Folliculitis Furancles(boils) Wound infections Brest abscess Carbuncles Cellulitis Styes
  • 25. Multiple carbuncles
  • 26. Abscess
  • 27. Wound infection
  • 28. cellulitis
  • 29. faurancles
  • 30. boils
  • 31. styes
  • 32. Brest abscess
  • 33. impetigo
  • 34. MUSCULOSKELETALINFECTIONS Osteomyelitis Arthritis etc
  • 35. osteomyaliytis
  • 36. RESPIRATORY INFECTIONS Tonsillitis Pharyngitis Sinusitis Otis Broncho npneumonia Lung abscess Empyemia
  • 37. Lung abscess
  • 38. tonsillitis
  • 39. CNS INFECTIONS Brainabscess Meningitis etc
  • 40. meningitis
  • 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. Food poisoning
  • 44. Toxic shock syndrome
  • 45. Scaled skin disease
  • 46. Staphylococcal infections
  • 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. 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. BICHEMICHAL REACTIONS Catalase - positive Oxidase - negative Coagulase -positive DNase -positive Phosphatase - positive Mannitiol fermentation -positve
  • 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. Slide coagulase test
  • 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. Tube coagulase test
  • 54. Mannitol fermentation
  • 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