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17 Cards in this Set
- Front
- Back
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What are the usual defense mechanisms of the GI tract?
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-Stomach has HCl
-Intestines: normal flora, peristalsis, sIgA, Phagocytes. |
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What are the 3 types of pathogenic mechanisms in the GI tract?
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1. Enterotoxins affect cell function (by either being ingested preformed or forming after ingestion)
2. Organism growth disrupts intestinal mucosa function 3. Organism growth damages intestinal mucosa |
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What are 4 symptoms associated with GI infection?
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1. Abdominal pain
2. Diarrhea 3. Dysentery 4. Botulism (neurological symptoms) |
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When and how should stool specimens be collected?
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-During the most acute phase of the disease.
-Collect 2-3 specimens if possible. -Don't settle for swabs - try to get fecal specimen if poss. |
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How should you hold a fecal specimen if unable to culture right away?
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Put in the refrigerator to prevent overgrowth of normal flora.
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When processing a stool culture, is a direct smear normally done?
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No - not unless it's requested.
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If a fecal smear is requested what would you be looking for?
What type of stain is used? |
Fecal leukocytes with Methylene blue.
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What does the presence of WBCs in a fecal specimen indicate?
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Presence of a pathogen - Salmonella, shigella, campy, C. difficile, or Cryptosporidium.
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You know the low/intermed selective enteric plates; what are the 2 high selective plates?
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-Brilliant green agar
-Bismuth sulfite agar |
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Other than enteric plates, what should be inoculated from a stool specimen?
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-CNA
-BA -Campy, CIN, SMAC, or TCBS. |
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What is the purpose of enrichment media?
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Keeps the normal flora from growing and promotes the growth of fastidious pathogens.
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What are the 3 normal types of enrichment broths?
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-Tetrathionate
-Selenite -GN broth |
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On a daily timeframe, how do you do an enteric workup?
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Day 1: possibly fecal leukocyte direct smear, inoculate primary.
Day 2: Screen for pathogens - inoculate nonferm. to TSI/LIA; subculture the enrichment broth. |
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What are 6 normal flora seen in the enteric specimen?
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-Enterobacteriaceae
-Streptococci (enterococci) -Anaerobes -Pseudomonas -Staphylococci -Yeast |
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What enteric pathogens would you culture FOOD (not stool) for?
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-Bacillus cereus
-Clostridium perfringens -Listeria |
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How would you test for Clostridium difficile?
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Toxin assay on stool
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How would you test for Clostridium botulinum?
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Toxin assay on serum.
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