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49 Cards in this Set
- Front
- Back
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what is a sterile site? |
-the nonfermenter is the only isolate |
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how is Genus identification made? |
-made through biochemical tests |
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what are the con's in a definitive ID in a nonfermenter? |
Con: costly & time consuming |
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how can you make a non-fermenter identification? |
Growth on McConkey: non-lactose fermenters Gram stain: gram neg rod Oxidase pos: most but not all strict aerobes O-F media: non-fermenter |
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key identifiers of P.aeruginosa |
-growth at 42 C -cetrimide resistant -pyocanin (pigment) |
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key identifiers of S.maltophilia |
-DNAse positive -oxidase NEGATIVE |
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key identifiers of Acinetobacter: |
-oxidase NEGATIVE -non motile -very inert -few biochemical reactions |
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if a non-fermenter is considered to breakdown carbohydrates oxidatively this means: |
-oxidizer or saccharolytic |
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if a non-fermenter is considered to not be able to breakdown carbohydrates than this means: |
-biochemically inert - nonoxidizers -asaccharolytic |
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non-fermenters account for how many clinical infections? |
-15% |
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general characteristics of a non-fermenter: |
-long, thin gram (-) bacilli or coccobacilli - most oxidase positive -nonreactive in TSI or KIA agar -OF media can distinguish between nonfermenters & weak fermenters -resistance to antibiotics |
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nonfermenters can be grouped based on reactions to what 3 test? |
1. growth on MacConkey agar 2. oxidase reaction 3. glucose oxidation (OF test) -possible 8 combinations of results used to group |
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characteristics of Pseudomonads: |
-Gram neg bacilli or coccobacilli -motile with polar or polar tuft flagella -oxidase & catalase POSITIVE -usually grow on MacConkey agar -usually oxidize carbohydrates ` |
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what are the virulence factors of P.aeruginosa? |
-phosphorylase hemolysin C -proteases -capsule -exotoxin S |
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Phosphorylase hemolysin C: (P.aeruginosa) |
-destroys pulmonary surfactant |
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Proteases (P.aeruginosa): |
-when present will cause hemorrhagic skin lesions |
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Capsule (p.aeruginosa): |
-polysaccharide or mucopolysaccharide in CF |
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Exotoxin S (P.aeruginosa) |
-halts protein synthesis, promotes tissue destruction |
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clinical infections caused by P.aeruginosa |
-bacteremia with ecthyma gangrenosum of the skin -wound infections -pulmonary disease (cystic fibrosis) -nosocomial UTIs -endocarditis -infections of burns -otitis externa- necrotizing skin rash (hot tub syndrome) |
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P.aeryginosa have the tendency to.... |
-invade vascular walls of vessels (systemic) |
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P.aeruginosa account for how many bacteremias and about how many nosocomial bacteremias? |
- 6.2% of all bacteremias -up to 75% of nosocomial bacteremias |
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poor prognostic factors of P.aeruginosa: |
-septic shock granulocytopenia -inappropriate antibiotic therapy -septic metastases |
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Additions virulence factors of P.aeruginosa: |
-adhesion: pili, adhesions -exoenzyme S (exoS) -exotoxin A (exoA) -elastases -hemolysins -leukocidin -alginate
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Adhesion- (P.aeruginosa-virulence factor) |
-pili -has two adhesion types |
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what are the two types of adhesions? |
-bind to mucin/ epithelial cells -bind to mucin only |
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exoenzymes S (exoS) |
-target is GTP-binding proteins -causes tissues destruction in lung infections |
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exotoxin A (exoA0 |
-same mechanism as diphtheria toxin (diff recptor) -binds to & inactivates elogation factor 2 (EF2), causing inhibition of protein synthesis & eventual cell death |
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Elastases: LasA, LasB, alkaline protease |
-destroy elastin containing lung tissues & elastin in blood vessel walls leading to pulmoary hemorrhages |
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what are the different hemolysins? |
-rhamnolipid -phospholipase C -leukocydin -alginate (polysaccharide) |
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rhamnolipid |
-able to solubilize phospholipids of lung surfactant -also inhibits ciliary function of respiratior epithelial cells |
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Phospholipase C |
-breaks down lipids & lecithin especially those solubilized by rhamnolipid |
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Leukocydin |
-lethal for WBCs -not hemolytic |
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Alginate (polysaccharide) |
SLIME: viscous gel around bacteria |
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what does the slime do? (alginate) |
-protects from phagocytosis -impairs diffusion of antibiotics -usually only in strains isolated from lungs of cystic fibrosis patients |
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what are the key identifications of pseudomonads? |
-most B hemolytic on blood agar -produce green metallic sheen from pyocyanin pigment -most produce pyoverdin -most stains produce a fruity, grapelike odor |
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pyocyanin pigment |
-green metallic sheen -antibacterial -damages epithelial tissue |
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pyoverdin |
-fluroescent pigment |
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what is the fruity, grapelike odor caused by? |
2-aminoacetophenone |
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Pseudomonas fluorescens & Pseudomonas putida are members of what group? |
-members of fluorescent group of pseudomonads |
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members of the fluorescent group of pseudomonads produce what? |
-produce pyoverdin |
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what is not produced by P.fluorescens & P.putida? |
- neither produce pyocyanin |
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P.fluorescens & P.putida both rarely cause clinical disease so therefore they... |
they both have low virulence |
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what three pseudomonas produce pyoverdin pigment? |
P.fluorescens, P. putida, & P. aeruginosa -all produce pyoverdin |
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what color is pyoverdin pigment? |
yellow-green, brown |
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what pseudomona only produces pyocyanin & grows at 42 C? |
-P. aeruginosa |
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what pseudomona is gelatin positive? |
-Ps. fluorescens |
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what Pseudomona is gelatin negative? |
-P. Putida |
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Pseudomona mendocina |
-not thought to cause human infections -Maltose neg -mannitol neg |
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Pseudomona Stutzeri |
-endocarditis & septicemis -dry wrinkled colonies -Maltose positive -Mannitol positive |
