GI Diseases Flashcards
What is the major host defense in the esophagus? Small/large intestines?
Motility/acidity
Motility/normal flora
What are the three major pathogens that infect the esophagus?
Candida
HSV
CMV
What is the major pathogen that infects the stomach?
H. Pylori
What are the four major pathogens of the Small/large intestines?
C. diff
E. coli
Salmonella
Shigella
What are the common ssx of esophagitis?
- Dysphagia wwo odynophagia
- Retrosternal pain
- Fever (sometimes)
What are the gross findings of candida infection of the esophagus?
White, non-ulcerative plaques
What are the gross findings of HSVI (II) infection of the esophagus?
Ulcerations
What is the most common viral infection of the esophagus?
HSV I
What are the gross characteristics of CMV infections of the esophagus?
Ulcerations
What species of candida is resistant to fluconazole?
Candida krusei
What are the findings of an esophagram with esophagitis?
Loss of the smooth appearance
What is the advantage of a culture over PCR?
PCR just tells you if it is there, not if it’s the causative agent
What is the treatment for candida esophagitis?
Oral fluconazole fro 2-3 weeks
What is the alternative to oral antifungals for candida esophagitis?
IV echinocandin or amp B
inhibit the synthesis of glucan in the cell wall, via noncompetitive inhibition of the enzyme 1,3-β glucan synthase
What is the treatment for herpes esophagitis? MOA?
Acyclovir
Converted by thymidine kinases to inhibit DNA polymerases
What is the treatment for CMV esophagitis? MOA?
IV ganciclovir or oral valganciclovir
Synthetic analogue of guanosine, that is converted into dGTP to inhibit DNA polymerases
What is the enzyme H. Pylori has that allows it to survive in the low pH of the stomach?
Urease
What is the effect of altered stomach lining/pH in the rest of the GI tract?
Alters flora in mouth and intestines
What are the three non-invasive ways to diagnose H. Pylori infection?
- Urea breath test
- Stool antigen
- Serology
What is the method of choice for diagnosing H. Pylori infection if an endoscopy is indicated? What may interfere with this?
Biopsy urease test
PPIs will alter this result
What is the major disadvantage of stool antigen testing for H. Pylori?
May have false positives if treated
What is the major downside of serology testing for H. Pylori infection?
Doesn’t distinguish between active and past infection
What is the treatment for H. Pylori infection? (3)
PPI
Clarithromycin
amox
How long should treatment last for H. Pylori before checking again?
6-8 weeks
When do IgG antibodies fall with H. Pylori infections?
6 months
When are false negative results seen with H. Pylori treatment?
Less than 4 weeks after treatment
Within 2 weeks of a PPI
When is an endoscopy indicated for GI tract infections?
If gastric ulcer and to exclude cancer
What is the clinical definition of diarrhea?
3 or more watery stools within a 24 hour period
When is a further diagnostic evaluation warranted for GI tract symptoms? (non-obvious)
- Temp of more than 101.3 F
- More than 6 unformed stools /24 hours of illness
What are the characteristics of diarrhea that can aid you in diagnosing the infection or assessing the severity?
- Frequency
- Volume
- Duration
What is the clinical definition of acute, persistent, and chronic diarrhea?
Acute = less than 2 weeks
2-4 weeks = persistent
More than 4 weeks = chronic
True or false: the vast majority of diarrhea cases in the US are caused by infectious agents
True
What are the things that can be elucidated from diarrhea samples?
- Parasitic infection
- Mal digested food
- Lipid droplets
Curved gram negative rod that causes diarrhea= ?
Vibrio cholerae
Reheated rice syndrome = ?
Bacillus cereus
Raw milk diarrhea?
Salmonella
Poultry or raw milk/cheese diarrhea = ?
Campylobacter
What is the common infectious cause of diarrhea that occurs in daycare centers?
Shigella
What are the foods associated with shellfish or coconut milk?
Vibrio cholerae
Processed meats bacteria = ?
Listeria monocytogenes
Home canned foods bacteria = ?
Clostridium spp
What are the four major viral causes of GI illnesses?
Rotavirus
Norovirus
Hep A
CMV
What parasite is characterized by daycare centers and ingestions of stream water?
Giardia
What are the endemic areas for entamoeba histolytica?
Mexico
What diarrhea causing parasite is found in daycare centers, swimming pools, and animal exposure?
Crytosporidium
What parasite is found in raspberries that causes diarrhea?
Cyclospora
Microsporidium diarrhea is usually found in whom?
AIDS pts
What is the incubation period for: bacillus cereus?
1-8 hours
What is the incubation period for: s. aureus
8-24 hours
What are the three major bacteria that have preformed toxins that cause GI illness
- Bacillus cereus
- S. Aureus
- C. Perfringens
What are the four major enterotoxic bacteria?
- V. Cholerae
- ETEC
- Klebsiella pneumoniae
- Aeromonas
What are the two major cytotoxic bacteria?
- C diff
- EHEC
What is the incubation period for enterotoxic bacteria?
8-72 hours
What is the incubation period for: cytotoxic bacteria?
Day(s)
Inflammatory or noninflammatory symptom: voluminous stool?
Non-inflammatory
Inflammatory or noninflammatory symptom: fecal leukocytes present
Inflammatory
What are the typical pathogens of inflammatory diarrhea? (3)
Shigella
Campy
Salmonella
What are the typical pathogens for noninflammatory diarrhea? (2)
VIbrio cholerae
ETEC
What is the therapy for inflammatory vs noninflammatory diarrhea?
Inflammatory = rehydrate and abx
Non = abx if severely ill
What is the bacteria that causes HUS?
E.coli O157:H7
What is the metabolic disturbance that can occur with HUS?
Azotemia
What is the approach to therapy for hemorrhagic diarrhea?
Supportive; abx may increase risk of HUS
What are the two major toxins that C.diff has?
Toxin A and toxin B
What is the best test for C. Diff?
Culture
Testing for C. Diff should be performed on what type of stool?
Diarrheal stool
True or false: testing for C.diff in stool in asymptomatic pts can prove useful
False–don’t do it
Is PCR widely available for C. Diff?
Not widely
What is the sensitivity/specificity of endoscopy for diagnosing C. Diff?
51 and 100%
What is the sensitivity/specificity of culture for diagnosing C. Diff?
90%ish for both
What is the sensitivity/specificity of cell culture cytotoxin test for diagnosing C. Diff?
70-100% for both
What is the sensitivity/specificity of EIA toxin test for diagnosing C. Diff?
65-95 sensitive
75-100 specific
What is the sensitivity/specificity of PCR for diagnosing C. Diff?
90s for both
What is the treatment for C. diff?
Vanco or metronidazole
What indicated a mild-moderate C. Diff infx? (2) What drug is indicated?
- WBC less than 15
- Cr less than 1.5x premorbid levels
Metronidazole
What indicated a severe C. Diff infx? (2) What drug is indicated?
- WBC greater than 15
- Cr more than 1.5x premorbid levels
Vanco
What is the dosage for vanco?
125mg
What is the abx of choice for a second bout of c.diff?
use the same regimen
True or false: metronidazole is the preferred abx of choice for recurrence /long term chronic C.diff therapy
False– do not use more than once
Are probiotics recommended to prevent primary CDI?
No–Limited data to support
What is the major side effect of long term metronidazole use?
Peripheral neuropathy
Who should never receive probiotics during/after C. DIff infx?
Immunosuppressed
Why are antiperistaltic agents not indicated for infectious diarrhea?
May cause toxic megacolon
What is the MOA of loperamide?
Loperamide is an opioid-receptor agonist and acts on the μ-opioid receptors in the myenteric plexus of the large intestine
