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Staph Morphology
Gram + cocci
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Staph division pattern
Divide on two planes, x and y axis
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Staph motility
Non-motile
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Staph and oxygen
Facultative anaerobe
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Staph and spores
Staph makes no spores
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Staph test how with catalase
Positive
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How does S. aureus test on coagulase
Positive
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S. aureus express what kind of capsule
5 or 8
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Where does staph. aureus colonize
Anterior nares, also skin
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What kind of bacteria is staph. aureus in terms of pathogenicity
Opportunistic pathogen
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Staph. aureus causes:
skin infection, pneumonia, endocarditis, osteomyelitis, would infection
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Staph. epidermidis inhabits:
- skin (normal microbiota, may protect against other pathogens)
- Can grow on artificial materials used in medicine
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What does staph. epidermidis infect?
Prosthetic devices, (heart valves and catheters)
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Staph. saprophyticus found where/causes
Normal flora, causes urinary tract infection in young women (cystitis)
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Staph. epidermidis tests how with coagulase
Negative (epidermidis is representative of coag-neg staph.)
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Staph. saprophyticus tests how with coagulase
Negative
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Staph. aureus diseases:
- SSSS (Staph. scalded skin syndrome)
- Food poisoning
- Skin infection (impetigo, folliculitis, furuncles/carbuncles)
- Tissue/wound infection
- Bacteremia/Endocarditis
- Pneumoniae
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Scaled skin syndrome (SSSS)
- Aka Ritter's disease Affects infants/children
- Clear w/o lasting effect, 7-10 days
- Staph. aureus disease
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Bullous Impetigo
- Staph. aureus culture from blisters
- Staph. aureus disease
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Food poisoning
- 1. Food stored poorly
- 2. Enterotoxin produces by S. aureus in food
- 3. Food consumed
- 4. Bacteria dies, toxin does it's thing (heat/acid resistant)
- 5. Illness ends with removal of toxins
- BACTERIA NOT NEEDED FOR ILLNESS, JUST TOXIN
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Staph skin infections
Impetigo, Folliculitis, Furuncles/Carbuncles
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Impetigo
Formation of pustules on skin, often rupture and form crusty lesionsStaph. aureus disease
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Folliculitis
- Pus-filled (pyogenic) infection of hair follicles (in eyelash is a stye)
- Staph. aureus disease
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Furuncles/Carbuncles
- Progression of folliculitis, carbuncles are clusters of furuncles.
- Staph. aureus disease
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Tissue/Wound infection
- Staph. aureus is great at this
- Gets in threw trauma
- Hard to prevent
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Bacteremia/endocarditi
- Staph. aureus, common cause
- Associated with use of dirty needles
- Infection of heart can be deadly (endo)
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Pneumonia
- Staph. aureus form can be deadly
- Spread orally or blood-borne
- Is highly oppurtunistic (attacks cystitc fibrosis or viral influenza)
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Important Staphyl enzymes
- Immune evasion/binding: Staphylokinase, Fibrinogen-binding protein, Protein A, Super Antigen
- Important Diagnostic Enzymes: Coagulase, Catalase
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Staphylokinase
- Activates plasminogen to form plasmin which digests fibrin clots
- This disrupts fibrin meshwork (keeps infection localized)
- Cleaves C3b, IgG
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Fibrinogen-binding protein
- Binds C3 to prevent lysis by complement
- Staph.
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Coagulase:
- Important for staph diagnostics
- Identifies Staph. aureus
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Catalase
Identifies between staph (+) and Strep (-)
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Protein A is a:
Super-antigen
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Protein A use in research
Binds to all antibodies, can be used to collect them all from a mixture if affixed to glass beads
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Staph. aureus uses what kind of toxin:
AB toxins: Panton-Valentine Leukocidin
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AB toxins
- A: active protein
- B: binding protein
- B gets A into cell, A produces virulence
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Panton-Valentine Leukocidin
- PV Leuko. made by <5% of Staph. aureus, most MRSA though
- Encoded by prophage
- Made up of LukS and LukF
- Make pores on phagocytic cell walls
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All 3 common types of Staph. aureus can be grown:
BAP @ 37C
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Differential/selective Media for Staph
- Mannitol-salts medium:
- High salt (7.5% NaCl)
- Inhibits most organism, Staph can grow though (selective)
- S. aureus ferments mannitol causing yellow (differential)
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What kinds of hymolysis can Staph. aureus show
Beta or Non-hemolytic (Gamma)
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Pigments forms by Staph
- S. aureus: gold colored
- S. epidermidis: white (no-pig)
- S. saprophyticus: white (no-pig)
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What does coagulase do?
- Converts fibrinogen to insoluble fibrin
- Bound: causes staphylococci to clump
- Free: reacts with globulin plasma factor to make staphylothrombin
- Can cause protective fibrin layer around staph. abscess
- Found in Staph. aureus
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How to conduct coagulase test
Dilute human blood plasma, mix with staph cells, look for clot.
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