Staphylococcus Department of pathogenic Biology of Gannan Medical College.
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Transcript of Staphylococcus Department of pathogenic Biology of Gannan Medical College.
StaphylococcusStaphylococcus
Department of pathogenic Biology of Gannan Medical College
Biological Biological characteristicscharacteristics
Gram positive cocci
arranged in irregular
grape – like clusters
Non-sporing and Non-
molite
1. Morphology:
2. Culture2. 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
White Citrine
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
SPASPAIgGIgG
Fc receptorFc receptor
PHAGOCYTEPHAGOCYTE
BACTERIUMBACTERIUM
(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)
Pathogenicity1.pathogenic factor
Surface structure : SPA ; Peptidoglycan;
CapsuleEnzyme : Coagulase ; Fibrnolysin; Heat-
stable nuclease; Hyaluronidase; LipaseToxin ; Staphylolysin ; Leukocidin ;
Enterotoxin ; Toxic shock syndrome
toxin-1 (TSST-1) ; Epidermolytic toxin
CoagulaseA 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 agarcoagulose testEnterotoxin 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.