staphylococcus department of pathogenic biology of gannan medical college
TRANSCRIPT
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StaphylococcusStaphylococcus
Department of pathogenic Biology of Gannan Medical College
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Biological Biological characteristicscharacteristics
Gram positive cocci
arranged in irregular
grape – like clusters
Non-sporing and Non-
molite
1. Morphology:
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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
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Staph saprophyticus Staph. epidermidi
Staph. aureus
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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 + + + -/ + -
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4. Antigenic structure
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(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
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SPASPAIgGIgG
Fc receptorFc receptor
PHAGOCYTEPHAGOCYTE
BACTERIUMBACTERIUM
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(2) polysaccharide (lipoteichoic acid LTA)
polysaccharide A ------- Staph. Aureus
polysaccharide B ------- Staph. epidermidis
(3) Capsular Polysaccharide
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5. Resistance:
resistant to dry; heat (80 ,30min); ℃
salt(10~15%)
sensitivity to: basic-dyes(crystal violet);
antibiotics and sulfonamides (antibiotic
resistance)
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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
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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
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Staphylolysin
Impairment of membrane permeadility;
cytotoxic effects on phagocytic and tissue cells
Protein
five kinds: ~
Staphylolysin-: main pathogenic
substance
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Leukocidin
Kill PMNs and M
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Protein
nine types: A-H
Heat stable (boiling for 30 min)
Cause a food poisoning characterized by
severe vomiting and diarrhea
Enterotoxin
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Toxic shock syndrome toxin-1 (TSST-1)
Induces multisystsm effects
superantigen effects
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Exfoliative toxin
Causes the scalded skin syndrome in
neonates, which results in widespread
blistering and loss of the epidermis.
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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
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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
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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.