Pseudomonas Flashcards
Pseudomonas is commonly encountered as a _____ pathogen
Nasocomial
Pseudomonas likes to be in ____ env
Moist
Pseudomonas aeruginosa manifests in
Lung optimistic infx Skin Urinary tract Ear Eye
Pseudomonas morphology
Aerobic Gram negative Rods Identified in agar (non fastidious) Has polar flagellum Many pili (type 4)
Alginate
Extracellular polysaccharide (mucous)
Produced by all pseudomonas
Esp seen in cystic fibrosis
Impt role in biofilm formation
Centrimide agar
Selective media allows growth of pseudomonas but not others
Lactose fermentation test
Shows e colo n most enteric bacteria bc they ferment lactose
Pseudomonas are nonfermentative
Cytochrome oxidase test
Pseudomonas has cytochrome enzyme so will cause reagent to turn black
Coloured pigments
Pseudomonas will turn blue yellow or rust when in culture with the pigments
Number — cause of ventilator associated pneumonia
#2 Staph aureus is #1
Number — gram neg cause for UTI
2,
Ecoli is one
P aeurginoas is associated most with ppl who have
Cystic fibrosis Or Burn patients Or Ppl with neutropenia
Collectins
Surfactant proteins A, D
Soluble molecules involved in innate resistance to p aeruginosa
Bacterial attachment is mediated by
Alginate
Pili n flagellum
Outer membrane proteins
Lipopolysaccharide (LPS) binds to CFTR cystic fibrosis transmembrane conductance regulator
Stages of biofilm formation (5)
Reversible attachment Irreversible attachment Microcolony formation 3S structures (stalks n towers) form Dispersion or detachment of bacteria
Quorum sensing system 2 types
Las
Rhl
Both use acyl homoserine lactomes as signalling molecules
Promote formation of biofilm
Ahl system
Ahl activates nf-kb protein complex
Produces cox2
That results in prostaglandin production
This induces mucous secretion vasodilation and edema
Ahl induces apoptosis of neutrophils and macrophages
Ahl increases production of inflammatory cytokines
Alginate is made of — and fx
D mannurinic acid
L glucuronic acid
Fx to anchor bacterial epithelial cell and to mucin
Protects from deposition opsinozation n phagocyte engulfment
Associated with chronic infx
Exotixin a
Enzyme
Immunosuppressant
Causes cel death by disrupting actin
Contributes to pathogen entry
Infx by injection
Exoenzymes s t u y
Introduced directly from bacterial cytosol into host cytoplasm
Requires direct cell contact
ExoS
Disrupt cell machiney
May activate monocytes
Targets endosomes and Golgi and ER
ExoU
Cleaves membrane phospholipids
Type 3 secretion system results in
Epithelial cell damage - facilitates bacterial spread n tissue invasion plus necrosis
Epithelial cell death - translocation of pore
Done by exoS&U
Happens when proteins are introduced to target cells
Elastases
Cause spread of infx
LasA n LasB act together to degrade elastin and damage elastin containing tissues
Cause damage to lung parenchyma
Alkaline protease cause tissue destruction
Phospholipase C is heat liable hemolysin that causes tissue destruction
Rhamnolipid is heat stable hemolysin
Acute infx
Tissue damage by proteases and toxins
Cell to cell signalling allows for cell density dependent production of extracellular factors
Chronic infx
In cystic fibrosis
Alginate protects from host
Low production of extra virulence factors
Tissue damage due to chronic inflammation
Pneumonia
1’ cause is bacterial invasion
2’ cause is bacteremia
Clinical manifestations
Swimmers ear Eye infx Skin folloxulitis Cns - meningitis n brain abscess Endocarditis- heart valves Pneumonia Bone n joint infx Urinary tract infx
Treatment
Combined use of antibiotics
Monotherapy good for some strains
Resistance
Intrinsic or acquired
