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40 Cards in this Set
- Front
- Back
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Enterobacteriaceae
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normal gut flora, opportunistic pathogens
primary pathogens 1. salmonella 2. shigella 3. yersinia 4. E. coli (some strains) |
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E characteristics
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gram negative bacilli
facultative oxidase negative ferment glucose |
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E growth media
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selective - bile salts & dyes
differential- lactose & pH coliforms = ferment lactose pathogens = lactose negative |
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Coliforms
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e. coli and related enteric bacteria (NOT pathogens) that may indicate fecal contamination in drinking water supplies
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E antigens
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O antigen = lipopolysaccharide
K antigen = capsular polysaccharide H antigen = flagella |
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E pathogenesis
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colonize epithelial surface and produce toxins
1. ETEC 2. EPEC 3. EHEC invade mucosal epithelium 1. shigella 2. Enteroinvasive E. coli invade gut lymphoid tissue, systemic dissemination 1. salmonella species 2. yersinia species |
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Bacterial Type III Secretion
1. salmonella 2. shigella 3. e. coli 4. yersinia 5. pseudomonas |
bacterial effector proteins directly into target cells
*evolved from flagella found in GRAM NEGATIVE encoded on 'pathogenicity islands' *present only in PATHOGENS Pathogenic function 1. disruption of host cell signaling 2. disturbance of inflammatory response 3. disturbance of cytoskeletal dynamics |
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Enterotoxigenic E. coli
*incubation 1-3 days *self-limiting 5 days |
acute watery diarrhea
colonize small intestine via fimbriae production of enterotoxins 1. heat labile toxin: like cholera, cAMP increases 2. heat stable toxin: increases cGMP |
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ETEC Dx, Tx, Epi
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clinical dx
maintain hydration, give antisecretory agents, antibiotics human are source can give prophylaxic antibiotics for travellers |
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Enteropathogenic E. coli
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persistent inflammatory non-bloody diarrhea
colonization of epithelial cells actin polymerization- via type III secretion sporadic disease and outbreaks in infants under 2 years of age |
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Enterohemorrhagic E. coli
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evolved from EPEC
bloody diarrhea and Hemolytic Uremic Syndrome (death, hemolytic anemia, thrombocytopenia, kidney failure-thrombus in glomeruli) colonization of colon and production of SHIGA toxin (AB structure with N glycosidase activity) inhibition of protein synthesis in target cells |
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EHEC dx, tx
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culture of SORBITOL non-fermenting
NO antibiotics (will increase risk of HUS and shiga release) supportive therapy for HUS *transfusions and dialysis *early aggressive hydration can decrease risk of HUS |
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EHEC epi
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serious disease in children and elderly
foodborne-person to person CATTLE are reservoir improperly cooked beef, unpasteurized juice, veggies, other food resistant to acidity, not many organisms needed to infect (100 bacteria = disease) |
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Shigella species
1. s. sonnei 2. s. flexneri 3. s. dysenteriae 4. s. boydii |
non-lactose fermenter
non-motile DYSENTERY - acute bloody diarrhea *severe intestinal cramping and tenesmus and high fever |
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Shigella pathogenesis
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resistant to gastric acidity
invasion of colonic mucosal epithelial cells extensive tissue damage cell to cell spread |
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S dx, tx, epi
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stool culture
Ab (very contagious and will shorten duration) humans are source very low infective dose (10) common in US |
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Salmonella enterica
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NON-lactose fermenter
h2s production |
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SE non-typhi
*uncommon bacteremia |
acute gastroenteritis
occasionally becomes systemic associated with compromised defense and AB use |
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SE non-typhi Pathogenesis
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colonization of small intestine
invasion of epithelial cell type III secretion 1. inject effector cells 2. actin binding 3. inositol signaling change |
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SE non-typhi DX & TX
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stool culture
blood culture in systemic disease no AB for healthy, AB for ICZ infection from animal, second to CJ for diarrhea |
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SE type Typhi
Enteric Fever- Typhoid Fever bacteremia |
virulence from capsular polysaccharide
10 days incubation, insidious onset prolonged fever- ROSE SPOT lesions, complication in 3rd week 1. ulceration 2. hemorrhage 3. perforation of intestine 4. metastatic infection |
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SE type Typhi Pathogenesis
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invasion of intestinal epithelial cells
survives in macrophage and monocyte seeds in gut lymphoid tissue- becomes metastatic from there |
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SE type Typhi Dx, Tx, Epi
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blood culture, serology, AB
human source, TYphoid Mary live attenuated vaccine (multiple doses) or purified virulence polysaccharide vaccine (single intramuscular inj) |
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Yersinia Entercolitica
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gram negative coccobacilli
lactose non-fermenting slower growth than other enteric enterocolitis = 1 to 3 week |
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YE pathogenesis
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invasion of peyer's patches
disruption of phagocytic process heat stable enterotoxin |
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YE culture, treatment, epi
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culture on enteric agar
self-limited acquired from animal - PORK |
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E. coli expressing K1 capsular polysaccharide
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Antiphagocytic K1 capsular polysaccharide
poorly immunogenic (capsule allows it to survive intracellularly in human brain microvascular endothelial cells |
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EColi K1
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culture from CSF, blood
AB therapy most common etiology of neonatal meningitis |
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UTI
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e.coli (80%)
s. saprophyticus (20%) do leukocyte esterase assay (dipstick) |
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UTI in women
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sexual activity
pregnancy |
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Klebsiella pneumoniae
(opportunistic enteric pathogen) |
lots of capsular polysaccharide production
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Enterobacter cloacae
(opportunistic enteric pathogen |
IV fluid contamination, pneumonia, surgical wound infection
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Serratia marcescens
(opportunistic enteric pathogen |
multiple AB resistance
sepsis, pneumonia, UTI |
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Proteus Mirabilis
(opportunistic enteric pathogen |
urease production, swarming motility, UTI
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SEPSIS mechanism
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GRAM NEGATIVE
1. LPS- Lipid A bound by serum LBP 2. this complex binds to CD14 and TLR4 on monocytes 3. TNF, IL-1 production and secretion via monocytes GRAM POSITIVE same, via peptidoglycan, lipoproteins, pyrogenic exotoxins |
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Noscomial Sepsis
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Gram Positive
-staphy and enterococcus Gram Negative -e.coli, klebsiella, enterobacter, pseudomonas Fungi -candida albicans TX= antimicrobial therapy supportive recombinant activated protein C |
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Pseudomonas aerugnosa
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GRAM NEGATIVE Bacillus
oxidase positive green pigments persists in soil and moist environments |
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PA disease
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opportunistic infections
pneumonia in CF patients burn wounds/sepsis nosocomial pneumonia, UTI, sepsis |
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PA pathogenesis
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adherence to mucins, ECM
biofilm formation antiphagocytic polysaccharide capsule exotoxin A ADP ribosyl transferase modifies EF2- inhibits protein translation |
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PA dx, tx
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culture
AB (has innate and acquired resistance) |
