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83 Cards in this Set
- Front
- Back
Gram + cocci, catalase +, Coagulase +
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Staph aureus
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What foods does staph like to infect?
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custards and meats (ham)
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Pathogenic features of staph
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enterotoxins (make right in the food!)
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Characteristics of Yersinia enterocolitica
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Gram - straight rod; lactose non-fermenter
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What foods does Yersinia enterocolitica like to infect?
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meat (even if refrigerated) and milk
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At what temps does yersinia like to grow?
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COOOOOOOLD (down to 4 C); peaks in the winter months
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Safety pin appearance on gram stain
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Yersinia
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Clinical manifestations of Yersinia enterocolitica
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invades mucosa of terminal ileum causing painful enlargement of the mesenteric nodes (may mimic appendicitis)
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curved, or comma shaped gram - rod
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Vibrio
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Gram -, curved rod with a single wimpy flagellum
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Vibrio
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What type of environment does Vibrio like?
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Water! (shellfish)
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What type of food is V. cholerae found in?
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shellfish and food and water in areas of poor sanitaiton
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What type of food is V. parahaemolyticus found in?
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Shellfish and sushi
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Pathogenesis of V. cholerae
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attaches to intestinal epithelial cell-->activates adenylate cyclase (Gsalpha)--> > cAMP--> promotes secretion of Cl- and H2O--> LOTS of watery "rice water" diarrhea
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Pathogenesis of V. parahaemolyticus
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Produces an enterotozin which causes intestinal inflammation and self-limiting diarrhea
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Gram + bacilli (rod), spore forming, aerobe
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Bacillu cereus
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Name 3 bugs that multiply and make toxins right in the food
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Staph and Bacillus cereus and Clostridium botulinum
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Fried Rice
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Bacillus cereus
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Pathogenesis of Bacillus cereus
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spores and can multiply in the food
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Box car shaped bug
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Bacillus cereus
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Characteristics of Bacillus
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Gram + rod; spore forming
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Foods Bacillus cereus likes to infect
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Fried rice and reheated beef (Spore survive initial cooking and multiply when the food is allowed to cool)
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Clinical manifestations of eating infected rice with Bacillus cereus
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Vomiting a few hours after eating
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Clinical manifestations of eating infected beef with Bacillus cereus
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Diarrhea 6-14 hours after eating
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Characteristics of Salmonella
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Gram - rod, motile
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Is Salmonella sensitive to acid?
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Yes (Antacids may help the bug take hold)
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Pathogenic features of Salmonella
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bug injects proteins into epithelial cells, causing big "ruffles"
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What foods does Salmonella like to infect?
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chicken products, processed foods, fruits and veggies, pet turtles, iguanas and birds, water contaminated with sewage (S. typhi)
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How do you differentiate between H. pylori and C. jejuni?
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C. jejuni is urease - (H. pylori is urease +)
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Characteristics of Campylobacter?
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Gram negative rod, comma or seagull shaped
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What sort of oxygen environment does Campylobacter like?
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Microaerophilic
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What temp does campylobacter like?
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Warm! (hence chx and warm milk)
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Why may campylobacter enter the bloodstream?
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Probably bc monocytes eat the bugs
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Pathogenesis of Campylobacter
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intestinal epithelial cells ingest the bug; once inside, campylobacter induces cell death leading to bowel wall ulceration and inflammation
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One of the MC causes of diarrhea in the US
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Campylobacter jejuni (fetus is more likely to give you sepsis)
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Foods that Campylobacter likes to infect
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poultry and raw milk
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K antigen, O antigen and H antigen
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E. coli
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What strain of E.coli is of most concern in food poisoning?
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EHEC (hemorrhagic)
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Pathogenesis of EHEC
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produce cytotoxins that may damage vessels in the bowel and glomerulus --> hemorrhagic colitis and Hemolytic Uremic Syndrome
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Bugs that may cause Hemolytic Uremic Syndrome
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E. coli and Shigella
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Characteristics of Listeria monocytogenes
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Gram + rod
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Pathogenic features of Listeria monocytogenes
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Escapes phagocytic vesicle within host cell and gets into host's cytoplasm (where there are no lysosomal enzymes being released!)
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Food that listeria likes to infect
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hot dogs, chicken, milk (pasteurization does NOT kill the bug!)
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Clinical manifestations of Listeria in most people and also in infants/elderly
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most: mild GI
Young and Old: sepsis, meningitis |
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How do you distinguish Clostridium perfringens from the other Clostridium gang?
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C. perfringens is NON motile
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Characteristics of Clostridium
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Gram + rod, anaerobic
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What oxygen environment does Clostridium like to live in?
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Anaerobic (hence canned goods)
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Pathogenic features of Clostridium
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spores; C. botulinum toxin forms right in food!; neurotoxin (screws up ACh release)
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What foods does Clostridium like to infect?
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home-canned goods, honey, baked potato, garlic in oil
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Clinical manifestations of C. botulinum
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descending flaccid paralysis (adults get better and newborns do not)
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Clinical manifestations of C. perfringens
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diarrhea (steam foods on buffet)
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Name 2 bugs with short incubation periods
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Staph and Bacillus
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Name 3 bugs with long incubation periods
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E. coli (may really long), Salmonella, Campylobacter
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Name the 2 members of the Vibrionaceae family
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Vibrio and Campylobacter
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Members of Enterobacteriaeceae
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Escherichia, Shigella, Salmonella, Proteus, kelbsiella, Enterobacter, Serratia, Citrobacter, and Yersinia
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Name 2 really important pathogenic features of enteric bacteria (E. coli)
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fimbria and pili (Cause secretory diarrhea)
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Where does most of the pathology of secretory diarrhea occur?
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Proximal SI (Where 90% of intestinal fluid absorption normally occurs)
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Virulence genes get swtiched on when the bug gets into the intestine
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V. cholerae
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Enterotoxins LT and ST change fluid transport in the gut from absorption to secretion
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ETEC (enterotoxigneic E. coli) causing secretory diarrhea
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Type of E. coli that causes secretory diarrhea not related to food poisoning
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ETEC (enterotoxigenic E. coli)
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How does EPEC (Enteropathogenic E. coli) cause diarrhea?
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NOT through toxin secretion but rather through a pilus to attach to epithelial cells
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Most important pathogens of Invasive Diarrhea
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Shigella and E. coli (EHEC)
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Shigella characteristics
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Gram - rod
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How is Shigella usually transmitted?
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person to person as the inoculum needed for Shigella infection is very small
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In acidic surroundings, the genes for acid-resistance get turned on; in less acidic conditions, the genes for invasion get turned on
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Shigella
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How does Shigella get to the basal surface to invade?
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Enter the M cells (they have a special protein to do this)
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Use host's actin to make rockets to propel themselves toward the cell membrane, making finger-like projections into the adjacent cell, which eats up the org and surrounding membranes
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Shigella
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What does the Shiga toxin of Shigella dysenteriae do?
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inactivates ribosomal RNA in the host cell, thereby stopping protein synthesis
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How is Enterohemorrhagic E. coli usually transmitted?
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from animals to humans, mostly through undercooked hamburger (needs a large # of bugs to infect!)
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Toxins of Enterohemorrhagic E. coli
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Shiga toxins 1 and 2 (or Shigalike or Vero toxins)
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Only bug that has been proven to cause antibiotic-associated diarrhea
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Clostridium difficile
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Characteristics of C. difficile
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obligate anaerobe, spore forming, gram + rod
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Oxygen conditions of C. diff
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Obligate anaerobe
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Pathogenesis of C. diff
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Exotoxins A and B bind to and kill cells in the bowel wall
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Pathology of C. diff (what does it show?)
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cell death, shallow ulcer formation and pseudomembrane formation
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Name some things that Antibody-Associated Diarrhea is associated with
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Broad spectrum antibiotics (clindamycin); anti-cancer drugs; bowel enemas or stimulatns, enteral feedings, close proximity to pts with C. diff
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How does osmotic diarrhea differ form diarrhea caused by C. diff?
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Pts with osmotic diarrhea should NOT have a fever or leukocytosis
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Dreaded complication of a C. diff infection; diarrhea or constipation and severe ab pain; bowel perforation and toxic megacolon possible
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Fulminant colitis
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What would you see in a stool smear for C. diff
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lots of PMNsand may be heme +
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How would you detect the toxins of C. diff (A and B)
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ELISA
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Gold standard for testing of C. diff
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Cytotoxicity testing
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Usual suspect of food poisoning from custards
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Staph auerus
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Most important pathogens of invasive diarrhea
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Shigella and EHEC (see lots of PMNs in a stool sample = invasive process); also may cause HUS
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