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83 Cards in this Set

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