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52 Cards in this Set
- Front
- Back
part of our normal flora and the most common opportunistic pathogen
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e. coli
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four disease that E. coli can cause
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1. gastrointestinal infections
2. UTI 3. bateremia 4. maningitis |
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three characteristics of E. coli that contribute to its pathogenicity
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1. K1 capsule (serum resistance)
2. Pili (UPEC) 3. shiga-like (cause of Gi symptoms) |
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causes 95% of all non-hospital acquired UTIs
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E. coli
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Many UTI bacteria are capable of binding
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mannosides - common constituents of uroepithelial cells and UTI
and are either mannose sensitive or not |
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an infection with UPEC is considered an infection when there is how much bacteria in urine
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10 to the 5 / ml
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a term used to describe the syndrome involving dysuria (burning feeling during urination), urgency, and occasionally suprapubic tenderness
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cystitis
usually involves lower urinary tract |
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resuts from urinary tract infection that has disseminated to kidney - flank pain, tenderness, and feer, dysuria, etc
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acute pylenophritis
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binds glycolipis on uroepithelial cells and erythrocytes and encoded by the pap operon
associated with E. coli |
P pili (MR = mannonse resitant)
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stochastic switching of phenotypic trait to provide phenotypic diversity inside and outside the host
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phase variation - E. coli associated with UTI
controlled by variety of mechanism strand slippage, methylation, recombination, influenced by enviromental factos |
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neo-natal meningitis
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20% - 40% of individuals care a type of E.coli that can colonize a new born via vertical transmission -
E.coli has resistance due to the KI capsule - crosses BBB to survive in CSF, proliferate, and cause tissue damage |
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E. coli associated bacteremia - often has serum resitance due to the production of
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K1 capsule
K1 capsule is made of sialic acids which are like host glycoproteins. the capsule is like that of neisseria meningitidis |
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leading cause of nosocomial bacteremia
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E. coli - crosses from UT tract ot blood
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e.coli has what kind of gram stain
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Gram negative
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Klebsiella pneumoniae has what kind of gram stain
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gram neg opportunistic
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how does the klebsiella pneumoniae's capsule contribute to the increased pathogenicity
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1. reduced phagocytosis
2. reduced complement susceptibility |
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what is used to help identify K. pneumoniae based on mucoid colony
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capsule
the capsule decreases phagocytosis and complement activation |
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differs from Klebsiella in that it is motile and generally less heavily encapsulated
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enterbacter cloacae
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does e. cloace cause diarrhea?
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no DIARRHEA!
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the two characteristic that are known to contribute to pathogenicity of proteu vulgaris
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1. flagella
2. urease synthesis |
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infections are seen secondary to broad spectrum antibiotic therapy or secondary to instrumentaiton - pneumonia is often contracted after use of contaminated respirator
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serratia marcessens
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serratia is different from the other enterobacteriaceae in that it is
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less likely to colonize GI tract and more assocaiated with respiratory and urinary tract (GI tract is imporatant reservoir among neonates)
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produces Ig-specific protease that influence pathogenicity
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serratia
also associated with septic arthritis |
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three acute infections caused by p. aeruginosa
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1. bacteremia in immune compormised patients
2. eye infections 3. burn infections |
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associate with Cystic fibrosis where pts are mor susceptible to a chronic bacterial infections
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p. auruginosa
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cannot ferment sugars. requires aerobic incubation. can grow via anaerobic respiration with nitrate as an electron acceptor, or ferment amino acid arginine
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p. aeruginosa
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ExoA exotoxin
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ADP-ribosylates elongation factor 2 (EF-2) which stops protein synthesis and elicits apoptosis of affected cells - P. aerugosa
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these are ADP-ribosylating enzymes that targes host regulatory proteisn and is secreted P. aeruganosa
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ExoS and ExoT
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cytotoxic exotoxin which ahs phospholipase activity; causes irreversible damage to cellular membranes and rapid necrotic death
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ExoU - P. auruginosa
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secretes elastase and phopholipases which breaks down elastin and phospholipids in lung surfactant in host cell membranes
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p. aeruginoa
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most frequently found in the water of cooling towers, resides w/in free-living amoeba
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Legionella pneumophilia
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sLegionella pneumophilia causes
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peneumonia
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Legionella pneumonia exhibits what kind of growh t
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intracellular and parasitism in amoebae
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transmission of Legionella pneumophilia
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airborn route from enviroment not from infected people
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Diagnosis of L. pneumonnia
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diret flourescnet Ab test in sputum -
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3 gram negative opportunistic pathogens which are lactose fermenting
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E. coli
K. pneumonia E. cloacae |
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why is p. aeruginosa described as obligate aerobe
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it does not ferment sugars - but can grow nitrate as an alternative alectron acceptor and grow on arginine fermentatively.
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3 surface determinants of E. coli
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LPS (O-antigen)
Flagella (H antigen) Capsule (K antigen) |
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virulence factors which are encoded on a plasmid in E. coli
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Hemolysin
Heat labile toxin (LT) heat stable (ST) |
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verotxin secreted by E.coli is also called
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shiga-like toxin
encoded on a lysogenic phage - interferes w/ protein synthesis via RNA cleavage (subunit A) and impacts cytoskeleton (subunit B) |
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causes HUS (hemolytic uremic syndrome)
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seen in about 7% of E. coli infections
hemolytic anemia, thrombocytopenia, acute renal failure etc.. |
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E. coli O157:H7 is a serotype which what kind of diarrhea
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bloody due to the shiga-like toxin
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shows Type III secretion system
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E. coli - enterohemorrhagic ecoli
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LEE
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pathogenenicity island which encodes the T3SSS, intimin, and tir
it is the locus for enterocyte effaceement seen in enterohemorrhagic E.coli |
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locus for enterocyte efacement
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LEE
"pathogeniccity island" EsB: pores in eukaryotic membrane EsA: type III filmaments TIR: E.Coli attachment Intimin: tiR binding protien on surface - these are effector protiens, LEE also involves a secretion apparatus |
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Tir
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involved in T3SS : allows for E coli attachment
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how does the T3SS system work
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protein moves across bacterial cytoplasm and outer membrane AND across host cell membrane through a needle into host cytoplasm
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shiga-like toxin secreted by and encoded on
how does it work |
secreted by E. coli
encoded on phage intrerferes with protein synthesis via its RNA cleavage activity (subunit A) and may impact cytoskeleton (subunity B) |
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Hemolysin secreed by enterhemmorhagic E.coli does what
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nutrient acquisition by by cytotoxic-pore formation in cells
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how does Sorbitol MacConkey Agar distinguis between commensal E. coli and O157:H7
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O157:H7 is sorbitol-negative while commensal E.coli are sorbitol-positive
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are E. coli, salmonella shigella all lactose what
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E. coli is lact +
salmonella and shigella is Lac - good diagnostic test |
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what is the serologic test for O157
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direct or latex agglutination test
or H7 seology an dtoxin analysis send to reference library |