Staphylococcus (2)

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  • 1. Staphylococcus Eva L. Dizon, M.D.,FPPS,FPIDSP

2. Staphylococcus Staphyle- Bunch of grapes 0.5 to 1 um Non motile Aerobic or Facultative Anaerobic Catalase positive Grow in media containing 10% NaCl at temp 18 to 40 C Present on the skin and mucuos membrane 3. Species

  • S. aureus
  • S. epidermidis
  • S. saphrophyticus
  • S. capitis
  • S. haemolyticus
  • Micrococcus sp
  • Stomatococcus mucilaginosus
  • Alloiococcus otitidis

4. Physiology and Structure 5. Structure 6. 7. Structure CAPSULE - loose fitting polysaccharide layer(slime layer) - protects bacteria by inhibitingchemotaxis and phagocytosis - facilitates adherence of bacteria tocatheters and synthetic materials PEPTIDOGLYCAN - half of the cell wall - consist of layers of glycan chains withalternating subunits of N acetylmuramicacid and N- acetylglucosamine - has endotoxin like activity 8. Structure TEICHOIC ACID-phosphate containing polymersbound to peptidoglycan layer or tocytplasmic membrane - mediates the attachment ofstaphylococcus to mucosal surfaces S. aureusRibitol teichoic acid with N-acetylglucosamine( Polysaccharide A)S. epidermidisglycerolteichoic acid with glucosyl residues (polysaccharide B)- 9. PROTEIN A-covalentlylinked to peptidoglycan - has affinity to Fc receptor of Ig- blocks opsonization and phagocytosis 10. Structure CYTOPLASMIC MEMBRANE-osmotic barrier for thecell and provides an anchorage for thebiosynthetic and respiratory enzyme COAGULASE and other SURFACE PROTEIN -Clumping factor or Bound coagulasebinds fibrinogen convert to insolublefibrin causing staphylococcus toclump - collagen , elastin and fibronectin bindingprotein 11. Toxins

  • A.5 Cytolytic or membrane damage toxin
  • Alpha
  • Beta
  • Gamma
  • Delta
  • Panton Valentine
  • B.2 Exfoliative toxin
  • C.8 Enterotoxin
  • D.Toxic Shock Syndrome Toxin(TSST 1)

12. Cytotoxins Lyse neutrophilsrelease of lysosomal enzymesdamage sorrounding tissues Alpha toxin disrupts the smooth muscle in bloodvessels- toxic to erythrocytes, hepatocytes,platelets, cultivated cells - integrates to host cell membrane poresefflux of K and influx of Na,Caosmotic swellingcell lysis - septic shock 13. Cytotoxin Beta Toxin-Sphingomyelinase C - specific for sphingomyelin andlysophosphatidylcholine - toxic to RBC, WBC,Macrophage and fibroblast - catalyze hydrolysis ofmembrane phospholipids insusceptible cells - tissue destruction and abscess formation Delta toxin-disrupts cell membrane - toxic to variety of cells 14. Cytotoxin

  • Gamma toxin and Panton Valentine
  • -both damage membrane of susceptible cells
  • - lyze nuetrophils and macrophages
  • - cell lysis is mediated by pore formation
  • Cause necrotizing skin infection
  • -PVL -potent leukotoxicity

15. Exfoliative toxin

  • ETA - heat stable
  • ETB heat labile
  • Serine protease
  • Exposuresplitting of desmosomes or intercellular bridges in the stratum granulosum epidermis
  • Common in neonates ETA and ETB binds to GM4 like glycolipids present in neonates

16. Enterotoxin

  • A-E, G-I
  • Stable to heating , resistant to hydrolysis
  • Enterotoxin A most commonly associated with disease
  • Enterotoxin C and D- contaminated milk products
  • Enterotoxin B- Pseudomembranous colitis
  • Superantigens

17. 18. TSST-1

  • Formerly pyrogenic exotoxin C and entertoxin F
  • Induce cytokine release from macrophage and T lymphocytes
  • Increase sensitivity to endotoxin
  • Produce leakage of endothelial cells
  • Penetrate mucosal barrier

19. Staphylococcal enzymes convert fibrinogen react with globulinplasma factorinsoluble fibrin to formstaphylothrombin Clumping Cause formation of fibrin layeraround abscess protecting staphylococcus from phagocytosis Coagulase BoundFree 20. Staphylococcal enzymes

  • Catalase - catalyze the conversion of toxic hydrogen peroxide to water and oxygen
  • Hyalurodinase - hydrolyzes hyaluronic acid in acellular matrix of connective tissuespread

21. Staphylococcal enzymes

  • Fibrinolysin- staphylokinase . Dissolve fibrin clot- aid in bacterial spreading
  • Lipases hydrolyse lipid to ensure survival in sebaceous areas of the body
  • Nuclease
  • Penicillinase- plasmid
  • Fatty acid modifying enzyme (FAME)- antibacterial lipid- prolonged bacterial survival

22. Epidemiology

  • Transient colonizer of skin
  • Nasal carriage anterior nasopharynx
  • Persistent carrier hospital personnel
  • Killed by high temperature and disinfectant
  • Direct contact, fomites
  • Handwashing

23. Sites of infection 24. Ritters disease or SSSS

  • Perioral erythema spreadbody bullous desquamation
  • Nikolsky sign
  • Bullous impetigo localized form of SSSS - localized blister - culture positive

25. SSSS most commonly in children and neonates. Starts abruptly with perioral (around the mouth) erythema with sunburn-like rash rapidly turning bright red spreading to bullae (large vesicle appearing as a circumscribed area) in 2-3 days and desquamating (peeling) within 5 days. 26. Staphylococcal food poisoning

  • Ham , salted pork, custard, potato sald, ice cream
  • Hands, Nasal carriage
  • I.P. 4 hrs
  • Vomiting, diarrhea, abd. pain

27. Toxic shock syndrome

  • Growth of organism in vagina or wound release of TSST-1
  • Fever, macular erythematous rashes, hypotension, multiorgan involvement, desquamation of palm and sole

28. TSS 29. Cutaneous infection

  • Impetigo
  • Folliculitis
  • Furuncle
  • Carbuncle
  • Wound infection

30. Folliculitis - superficial folliculitis is essentially a staphylococcalimpetigo in which a small area of erythema develops around a hair follicle and subsequently becomes a dome-shaped pustule. Carbuncle - a deep-seated pyogenic infection of the skin and subcutaneous tissues. 31. Impetigo - a contagious superficial pyoderma, caused by S. aureus and Streptococcus pyogenes, that begins with a superficial flaccid vesicle whichruptures and forms a thick yellowish crust, most commonly occurring in the face. 32. Others

  • Bacteremia
  • Endocarditis
  • Pneumonia
  • Empyema
  • Osteomyelitis
  • Septic arthritis

33. Pneumonia 34. S.Epidermidis and CNS

  • Endocarditis- native or artificial valves
  • Catheter and shunt infection
  • Prosthetic joint infection
  • UTI

35. Laboratory diagnosis Microscopy Culture Grow rapidly within 24 hours Large, golden, smooth colonies Blood Agar- hemolysis Selective media- add NaCl 7.5% Mannitol fermented by S. aureus Serology InsensitiveAntibody against teichoic acid Bacteremia. EndocarditisAfter 2 weeks 36. Culture S. aureus 37. S. epidermidisS. saphrophyticus 38. Coagulase test Showing positive (upper tube) and negative (lower tube) coagulase tests. 39. Mannitol Salt Agar test 40. Identification

  • Biochemical testing CoagulaseHeat stablenuclease Alkaline phospatase
  • Mannitol fermentation test

41. Treatment and Prevention

  • Semisynthetic penicillinase resistant penicillin
  • Resistance ( mecgene A codes for PBP 2)

42. 43. 44. Thank You