Staphylococcus Department of pathogenic Biology of Gannan Medical College

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

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

Staph saprophyticus Staph. epidermidi Staph. aureus

3. Classification: Table. Major properties of three species of taphylococci Main property Staph. aureus Staph. epidermidi Staph saprophyticus Pigmentation Golden yellow WhiteCitrine Coagulase+-- Hemolysin+-- Leukocidins+-- SPA+-- Pathogenicity+ + +-/ +-

4. Antigenic structure

(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

SPA IgG Fc receptor PHAGOCYTE BACTERIUM

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

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

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

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

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

Leukocidin Kill PMNs and M 

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

Toxic shock syndrome toxin-1 (TSST-1)  Induces multisystsm effects  superantigen effects

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

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

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

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.