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114 Cards in this Set
- Front
- Back
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Diarrhea is both a symptom and a sign. What is the symptom(s)?
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increased frequency, increased volume, decreased consistency
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Diarrhea is both a symptom and a sign. What is the sign?
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Stool weight > 150-200g per 24hrs
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Diarrhea can be classified as either acute or chronic. How is acute diarrhea defined?
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Diarrhea of less than 2-3 weeks duration.
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True or False: Typically, acute diarrhea is self-limited, but a physician should be seen?
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False. It is self-limited and commonly does not require evaluation.
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What is the most common etiology of acute diarrhea?
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infections
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Diarrhea can be classified as either acute or chronic. How is chronic diarrhea defined?
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Diarrhea that lasts more than 3 weeks
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What does chronic diarrhea generally indicate?
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A non-infectious etiology like celiac dz or IBD
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What are the most common bacterial causes of diarrhea?
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Salmonella, campylobacter, shigella, E. coli (O157:H7), C. difficile
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What are the most common viral causes of diarrhea?
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Calciviruses (Noro), Rotavirus, Adenovirus, Astrovirus
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What are the most common protozoal causes of diarrhea?
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Cryptosporidium, Giardia, Cyclospora, Entamoeba histolytica
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What are the two mechanisms by which infectious agents cause diarrhea?
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1. Direct tissue destruction
2. Toxin-mediated secretion |
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If food-borne illness symptoms begin w/in 6 hours, what are you thinking?
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preformed toxins like Staph aureus and Bacillus cereus
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If food-borne illness symptoms begin w/in 16 hours, what are you thinking?
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Clostridium perfringes
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If food-borne illness symptoms begin > 16 hours, what are you thinking?
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viral or bacterial infection
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Bacteria that invade deep into the tissues require 1-2 days to incubate. Give some examples of these organisms.
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Salmonella, campylobacter, shigella, enteroinvasive E. coli
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Bacteria that have cyto or enterotoxins incubate for 8-72 hours. Give some examples.
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Enterotoxic E. coli and Vibrio cholerae
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What symptoms lead you to think the infection is in the small intestine?
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Large volume, no urgency/tenesmus
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What symptoms lead you to think the infection is in the large intestine?
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Frequent, small volume, bloody
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What should you do if a pt has systemic toxicity, severe pain, dehydration, bloody stools, or if sx persist > 24hrs?
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stool studies (incl. fecal WBCs, ova & parasites, occult blood,
C. diff toxin (esp. if recent abx use) CBC w/ diff, blood cx Serum electrolytes if needed to manage dehydration |
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There are 4 types of chronic diarrhea. What are they?
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Osmotic (incl. malabsorption), Secretory, Inflammatory, Motility
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What is the usual cause of Motility related chronic diarrhea?
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IBS
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Describe the pathophy of osmotic/malabsorption diarrhea.
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osmotic load in the intestine resulting from retention of H2O in the lumen.
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Describe the pathophys of secretory diarrhea.
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Excess secretion of electrolytes and water into the intestinal lumen.
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What is the pathophys of inflammatory diarrhea?
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exudation of fluid and protein from the intestinal lumen
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What is the pathophys of motility diarrhea?
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Rapid transit through the colon
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Which section of the gi tract absorbs the most fluid?
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jejunum (4.5L)
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Will osmotic diarrhea resolve with fasting?
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Yes!
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How would you describe osmotic diarrhea from a looking in the toilet perspective?
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Large volume and malodorous
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Osmotic diarrhea can result from mucosal dz and osmotic agents in the lumen. Describe the pathophys of mucosal dz leading to diarrhea.
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damage to bowel wall --> solutes from diet not absorbed --> H2O not absorbed --> diarrhea
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What are some mucosal diseases of the small intestine that lead to osmotic diarrhea?
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celiac dz, tropical sprue, Whipple's dz
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What are some mucosal diseases of the colon that lead to osmotic diarrhea?
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IBS, infections, etc.
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Osmotic agents in the lumen of the intestine can lead to malabsorption and osmotic diarrhea. What are some causes of malabsorption?
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Pancreatic insufficiency and small bowel bacterial overgrowth
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What are some exogenous agents that can cause osmotic diarrhea?
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osmotic laxative, sorbitol, fructose (if GLUT5 mutation), lactose in intolerant pts.
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By what percentage do exocrine secretions have to decrease before you are PI?
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90%
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What are some causes of exocrine pancreatic insufficiency?
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EtOH, CF, pancreatic resection, pancreatic cancer, somatostatinoma
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Motility disorders, strictures, etc. lead to decreased transit in the colon which leads to overgrowth of bacteria in the small bowel. How does this cause osmotic diarrhea?
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Deconjugation of bile acids and direct damage to the mucosa increase the osmotic load.
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How do you dx a bacterial overgrowth on the small intestine?
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small bowel follow through study
hydrogen breath test culture empiric trial of abx (tetracycline, cipro) |
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What characterizes secretory diarrhea?
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substantially elevated stool volumes and associated hypokalemia
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True or False: Secretory diarrhea continues despite fasting?
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TRUE
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What is the prototypical cause of secretory diarrhea?
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Vibrio cholerae
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What is the pathophys of secretory diarrhea?
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increase in cAMP or cGMP constituitively activates CFTR
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What are some organisms that can cause secretory diarrhea?
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Vibrio cholerae, C. diff, E. coli (O157:H7), shigella
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What kind of diarrhea do VIPomas, gastrinoma, and carcinoid endocrine tumors cause?
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secretory
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What are some inflammatory cell products that can cause a secretory diarrhea?
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prostaglandin and leukotriene products, PAF, histamine, serotonin, etc.
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How do you estimate the stool osmotic gap?
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290 (or plasma osmolality) - 2 x (stool NA + stool K)
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What is a normal stool-serum osmolality gap?
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< or = 10
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True or False: Secretory diarrhea has a high osmolality gap?
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False! It should be normal.
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What is the osmotic gap of osmotic diarrhea?
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> 60
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What are some features of inflammatory diarrhea?
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WBCs in the stool
Blood in the stool Systemic sx such as fever Rectal inflammation, tenesmus, urgency |
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What are the most common causes of inflammatory diarrhea?
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IBD
Enteroinvasive E. coli Shigella Salmonella C. diff |
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WBCs in inflammatory diarrhea typically indicate ___ involvement.
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colonic
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What is sudan stain used for?
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to identify fecal fat
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When is it normal to see WBCs in stool?
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NEVER!!!
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What pathogens are frequently picked up in well water and fresh water ponds?
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Aeromonas and Pleisiomonas
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___ are the only cells in the body that make hydrogen.
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Bacteria
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What is the hydrogen breath test used for?
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assessing lactose intolerance and small bowel bacterial overgrowth
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What is the capsule endoscopy useful for?
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identifying celiac dz and crohn's dz
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What makes Crohn's jump out on histopath?
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granulomas
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What makes UC jump out in histopath?
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crypt abcess
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Mutations in HLA DR and DQ are assoc w/ what?
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Celiac dz
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What antibodies are detectable in pts w/ Celiac dz?
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Anti-endomesial Ab, anti-TTG (tissue transglutaminase)
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ASCA/ANCA levels may be elevated with what dz?
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IBD
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transmission of amebiasis
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fecal oral
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in which pt population is amebiasis more common and serious
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immunocompromised
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what is the gross path of amebiasis
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friable, erythematous mucosa and ulceration
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the microscopic path of the amebiasis is unique in that the ulcers are ___ shaped
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FLASK shaped
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the ulcers in amebiasis extend to which layer of the mucosa
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muscularis mucosae
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what 4 complications/manifestations of ingesting amebas
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liver abscess, lung abscess, diarrhea, ulceration in the colon (amebic collitis)
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what part of the mucosa does cryptosporidium colonize
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the brush border of the columnar epithelia. they line the surface epithelium and crypts
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T/F: chlorination kills cryptosportidium
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FALSE- oocysts resist cholorination
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what organs does cryptosporidum colonize
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stomach, sm and lg intestines, and biliary tract
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are cryptospordium intra or extra cellular in the gut
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it is considered intracellular because they are beneath host cell membrane (Note: they are not in the cytoplasm)
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cryptosporidium develop in ___ ___ which replace the ___ of the gut
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cryptosporidium develop in PARASITOPHORUS VACUOLES which replace the MICROVILLUS BORDER of the gut
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what does the host response to cryptosporidium include
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increased numbers of lymphocytes in the lamina propria and mild epithelial damage
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T/F: cryptosporidium derives its nutrition from the luminal food stream
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FALSE- it retrieves its nutrition from the host cell it is attached to
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what is an advantage to cryptosporidium of being in the location where it lives in the host
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since it is beneath the host cell membrane it is protected from host immune recognition
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T/F: cryptosporidium are PAS positive organisms
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TRUE! According to Goljan this will be on step 1!
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CMV infects what types of cells
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endothelium and fibroblasts mainly (can sometimes be seen in smooth muscle fibers of the muscularis mucosae though)
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how does CMV cause destruction to the mucosa
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it causes ischemic necrosis and ulceration
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what are two complications of the ulcers that develop in advanced CMV disease
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bleeding and perforation
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HSV infects what cell type
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squamos epithelium
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what does the gross path of CMV infection look like
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shallow ulcers with white necrotic debris center and erythematous border
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which regions of the GI tract are commonly effected by HSV
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esophagus or anal canal
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the esophagus is usually affected by which HSV: type 1 or type 2
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type 1
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the anal region is usually affected by which HSV: type 1 or type 2
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type 2
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T/F: all cases of HSV GI infx are in immunosuppressed pts
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false- although most cases are seen in immunocomp pts, some are seen in immunocompetent pts
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a distinctive micropath feature of HSV includes ___ ___ intranuclear inclusions
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ground glass
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what is the herpetic cytopathic effect
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1. multi nucleated squamos epithelial cells
2. ground glass nucleoplasm containing viral particles 3. margination of normal chromatin forming a peripheral rim |
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histopath of HSV
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dirty necrosis and granulation tissue, and basophilic ground glass intranuc inclusions and often multi nucleated epithelial cells
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when you see "falling leaves" on a path slide what disease should you think of
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Giardia infection
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what life stage of giardia infects humans
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cysts (as few as ten are enough to result in infection)
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T/F: giardia can be eliminated by chlorination
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FALSE! they are resistant to chlorination
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T/F: giardia can be removed via filtration
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True!
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transmission of giardia
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fecal oral (esp in daycare centers and among homosexual men)
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T/F: giardia causes acute diarrhea
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false- giardia can cause chronic diarrhea and malabsorption
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pathogenesis of giardia
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trophozoites adhere to mucosal surface forming barrier to absoprtion and damage to microvilli-->mucosal enzyme deficiency (e.g. acquired lactase deficiency that resolves with infection)
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what is the most common cause of epidemic water borne diarrhea
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giardia
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what furry animal is giardia associated with
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beavers (beaver fever)...beavers are furry, right?
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what is whipples disease
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a system infection by gram positive actinomycete Troheryma whipplei, it involves the small bowel in most patients
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histopath of whipple's disease
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small bowel mucosa containing macrophages with pale granular cytoplasm (strongly PAS+)-->expanding the lamina propria and widening the villi, lipid driplets scattered throughout lamina propria
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what is melanosis coli
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black discoloration of the colon from pigment deposition in macrophages in the lamina propria
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what can cause melanosis coli
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laxatives and other drugs
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what are the two types of microscopic colitis
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lymphocytic and collagenous
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lymphocytic colitis is common in ___ disease pts
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celiac
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histology in microscopic colitis shows preserved architecture with ___ in the epithelium +/- subepithelial ___
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lymphoctes, collagen band (note: if its + collagen band its collagenous colitis and if its - collagenous band its lymphocytic colitis)
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lymphocytic colitis is usually seen in ____
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little old ladies
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what is the normal villus to crypt ratio in the duodenum
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3 to 1
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what is celiac disease
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immune mediated disease due to gluten sensitivity results in enterocyte damage
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what is a major histopath feature of celiac disease
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villous blunting (because crypt cells fail to regenerate after damage)
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which part of the intestine is celiac disease most severe
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distal duodenum and proximal jejunum
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what are three histopath findings in celiac disease
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1. villous blunting
2. lymphs and plasma cells in the lamina propria 3. increased lymphs in epithelium |
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how do you dx celiac dz
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small bowel bx, clinical improvement on gluten free diet, serologic tests
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how do the crypts change in celiac disease
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they are lengthened due to hyperplasia after villus injury
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how do the surface epithelial cells change in celiac disease
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shorter with more lymphocytes, and fusion of microvilli
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