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Staphylococcus

Staphylococcus. Department of pathogenic Biology of Gannan Medical College. Biological characteristics. 1. Morphology:. Gram positive cocci arranged in irregular grape – like clusters Non-sporing and Non-molite. 2. Culture. Facultative anaerobes

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Staphylococcus

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  1. Staphylococcus Department of pathogenic Biology of Gannan Medical College

  2. Biological characteristics 1. Morphology: • Gram positive cocci • arranged in irregular • grape – like clusters • Non-sporing and Non-molite

  3. 2. Culture • Facultative anaerobes • temperature : 28~38℃ (37℃); pH : 4.5~9.8 (7.4) • blood agar-----haemolysis • Colony : 1~2 mm, circular, smooth, shiny surface, opaque, various pigments

  4. Staph. aureus Staph. epidermidi Staph saprophyticus

  5. 3. Classification: Table. Major properties of three species of taphylococci

  6. 4. Antigenic structure

  7. (1) SPA (staphylococcal protein A) • cell wall protein MW 13,000~42,000 • it combines nonspecifically with the Fc-portion of human IgG • antiphagocytosis • coagglutination • damage platelet • activate B cell

  8. PHAGOCYTE Fc receptor SPA IgG BACTERIUM

  9. (2) polysaccharide (lipoteichoic acid LTA) • polysaccharide A ------- Staph. Aureus • polysaccharide B ------- Staph. epidermidis (3) Capsular Polysaccharide

  10. 5. Resistance: • resistant to dry; heat (80℃,30min); salt(10~15%) • sensitivity to: basic-dyes(crystal violet); • antibiotics and sulfonamides (antibiotic resistance)

  11. Pathogenicity 1.pathogenic factor • Surface structure：SPA ; Peptidoglycan; Capsule • Enzyme ：Coagulase；Fibrnolysin; Heat- stable nuclease; Hyaluronidase; Lipase • Toxin；Staphylolysin；Leukocidin ； Enterotoxin ；Toxic shock syndrome toxin-1 (TSST-1) ；Epidermolytic toxin

  12. Coagulase • A enzyme that convers fibrinogen in citrated human or rabbit plasma into fibrin • Extracellular coagulase • an extracellular enzyme which activates a coagulase-reacting factor (CRF) normally present in plasma , causing the plasma to clot by theconversion of fibrinogen to fibrin (in tube). • Bound coagulase---------fibrinogen • to inhibit the phagocytosis of macrocytes and damage of bacteriacide substances in humor by coating the organisms with fibrin

  13. Staphylolysin • Impairment of membrane permeadility; cytotoxic effects on phagocytic and tissue cells • Protein • five kinds: ~  • Staphylolysin-: main pathogenic substance

  14. Leukocidin Kill PMNs and M

  15. Enterotoxin • Protein • nine types: A-H • Heat stable (boiling for 30 min) • Cause a food poisoning characterized by severe vomiting and diarrhea

  16. Toxic shock syndrome toxin-1 (TSST-1) • Induces multisystsm effects • superantigen effects

  17. Exfoliative toxin Causes the scalded skin syndrome in neonates, which results in widespread blistering and loss of the epidermis.

  18. 2.pathogensis • local infection • skin infection: hair folliculitis; boil; carbuncle; impetigo • organ infection: pneumonia; meningitis. • Systemic infection: Septicemia; pyemia • toxin diseases • Food poisoning (enterotoxin) • TSS(Toxic shock syndrome) • SSSS(staphylococcal scalded skin syndrome) • Staphylococcal enteritis

  19. Laboratory diagnosis • specimen: pus ; sputum ; blood ; food/faeces or vomit (food poisoning) ; mid-stream urine (pyelonephritis or cystisis) • direct smear :gram stain • isolation and identification: blood agar • coagulose test • Enterotoxin test and animal test

  20. Treatment Since strains of Staph. aureus vary in sensitivity to different antibiotics, treatment should be base on the results of sensitivity test made on a culture of the strain isolated from the patient.

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