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31 Cards in this Set
- Front
- Back
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Salmonella: bacteria characteristics
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Gram negative rod
H2S positive Lac negative Peritrichous flagella (motile) |
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Typhoid vs. non-typhoid
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Typhoid: systemic; has a capsule; causes septicemia; disseminates to liver and spleen; requires long-term ABs; carrier state possible from biliary duct
Non-typhoid: rare septicemia; no capsule; self-limiting; zoonotic |
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Salmonella pathogenesis
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Facultative intracellular
Invades host cell with T3SS Invades M cells and epithelial cells Evades macrophages by preventing lysosomal-endosomal fusion |
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T3SS used by...
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Salmonella
Shigella Yersinia EPEC EHEC |
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These pathogens lyse endosomal membrane and grow in host macrophage cytoplasm
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Shigella
Listeria |
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Shigella: bacteria characteristics
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Gram negative rod
Non-motile Lac (-) H2S (-) Produces shiga toxin |
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HUS (hemolytic uremic syndrome) caused by...
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Shigella
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Shigella: pathogenesis
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Invades M cells of gut
Lives in macrophages, replicates Lyses endsome and lives in cytoplasm Can infect epithelium basolaterally Can move between cells via actin-based motility Causes inflammation, compromised intestinal barrier |
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Shiga toxin
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Produced by shigella dysenteriae and EHEC
Prevents absorption of glucose, nutrients from lumen Associated with HUS |
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Campylobacter jejuni: bacteria characteristics
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Gram negative CURVED rod
Flagellated (motile) Grows on microaerophilic (charcoal) Produces cytolethal distending toxin *Curved, Cytolethal toxin, Cell Cycle arrest, Campy* |
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Campylobacter jejuni pathogenesis
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Causes inflammatory diarrhea
Produces cytolethal distending toxin that causes cell cycle arrest |
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Listeria monocytogenes: bacteria characteristics
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Gram positive rod
Facultative intracelluar Actin-based motility Has flagella, but not active at body temp |
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Actin-based motility
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Shigella
Listeria monocytogenes |
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Enteroinvasive pathogens
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Salmonella
Shigella Campylobacter jejuni Listeria monocytogenes |
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Listeria pathogenesis and symptoms
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Lyses macrophage endosome and lives in cytosol
Actin-based motility - causes inflammation **Commonly causes vomiting, not diarrhea** Important in pregnancy |
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Enterotoxigenic bacteria
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Vibrio cholera
C. difficile |
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Vibrio cholera: bacteria characteristics
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Gram neg curved
Highly motile - darting motility - polar flagellum |
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Vibrio cholera: epidemiology and symptoms
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Water is reservoir
Lives on surfaces High infectious dose But can have hyperinfectious types Acute onset Rice water stool Hypokalemia, cardiac arrhythmia, renal failure, hypovolemia and hypotensive shock |
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Vibrio cholera: pathogenesis
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Virulence: motility, proteases, PILI, toxin
Toxin: AB toxin GM1 ganglioside organization Endocytosis Acid activation when cleave S-S A enters cytosol Targets adenylate cyclase by turning Gs on cAMP dysreg (high levels) Ions pumped out, water leaves |
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Cholera toxin vs. C. diff toxin
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Cholera targets Gs by making constitutively active
C. diff inhibits Rho-GTPase that normally turns off signaling |
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Clostridia difficile: bacteria characteristics
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Gram positive rod
Obligate anaerobes (or slightly aerotolerant) Spore forming- refractive to disinfectants Two toxins: A and B |
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C. diff pathogenesis
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A and B toxins (both are AB toxins)
A: enterotoxin B: cytotoxin Disruption of host actin Cell rounding and necrosis Increased colonic permeability Inflammation PMN infiltration Toxin taken up similarly (RME), but inhibits Rho-GTPase |
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Enteropathogenic pathogens
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EHEC
EPEC H. Pylori |
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H. Pylori
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Produces mucinases
Attaches to epithelium Produces urease converts urea to ammonia and Co2 Reduces acidity in local env Causes apoptosis and inflammation without entering cells Uses T4SS |
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E. Coli: bacteria characteristics
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Gram neg rods
Virulence encoded on plasmids, phages, pathogenicity islands |
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EHEC and EPEC
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Form attaching and effacing lesions: pedestal
EPEC: interferes with epithelium, causing inflammation EHEC: bonus toxin: shiga-like toxin --> hemorrhagic colitis |
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ETEC
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Produces a cholera-like toxin
Causes cholera-like disease: lots of fluid loss Does NOT have darting motility |
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ETEC vs. cholera
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ETEC does not have darting motility
Cholera has darting motility |
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EIEC
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Similar pathogenesis to shigella
Invades and multiplies in epithelial cells Causes inflammatory diarrhea No toxin Moves between cells, causing damage |
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Gram positive
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Clostridia (C. diff) - enterotoxigenic
Listeria monocytogenes - enteroinvasive |
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Gram negative
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Salmonella
Shigella Campylobacter Vibrio cholera E. Coli H. Pylori |
