Malabsoprtion And Infectious Enterocolitis Flashcards

1
Q

Definition of diarrhea and dysentery

A

Diarrhea = increase in stool mass/frequency/fluidity typically over 200g of feces a day
- **accounts for >700,000 deaths of children <5yrs of age (2nd leading cause of death in this age group)

Dysentery = painful bloody small-volume diarrhea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 major categories of diarrhea?

A

1) malabsorptive diarrhea
- inadequate nutrient absorption associated with steatorrhea
- relieved by fasting

2) osmotic diarrhea
- due to osmotic forces exerted by unabsorbed luminal solutes
- *example = lactase deficiency

3) secretory diarrhea
- due to isotonic stools
- NOT relieved by fasting

4) exudative diarrhea
- inflammatory disease with Purulent bloody stools
- NOT relieved by fasting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Malabsorption diarrhea

A

“Chronic diarrhea”

Defective absorption of fats, fat and water soluble vitamins, proteins, carbs, electrolytes, minerals and water

Symptoms:

  • weight loss
  • anorexia
  • abdominal distention and pain
  • muscle wasting
  • borborygmi (rumbling noises in intestines)

***hall mark = steatorrhea

Most commonly associated with

  • pancreatic insufficiency
  • celiac disease
  • Crohn’s disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 4 phases of nutrient absorption that could cause malabsorptive diarrhea

A

1) intraluminal digestion
- proteins/carbs/fats are broken down into absorbed forms

2) terminal digestion
- hydrolysis of carbs/peptides/disaccharides and peptidases (brush border)

3) transepithelial transport
- transportation of nutrients/fluid/electrolytes across small-intestinal epithelium

4) lymphatic transport of lipids

**note: only one of these needs to be affected to produce malabsorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Cystic fibrosis review

A

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR)
- interferes with bicarbonate/sodium and water secretion which results in luminal dehydration

pancreas ducts are plugged by thick mucus which leads to chronic auto digestion of the pancreas (>80% sees pancreatic insufficiency)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Celiac disease

“Celiac sprue/ gluten sensitive enteropathy”

A

Immune-mediated enteropathy which is triggered by the presence of gluten In sensative patients

  • prevalence = 0.5-1%
  • more common in white people

Needs histological and serologic finds for specific diagnosis of celiac disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the pathogenesis of celiac disease

A

1) gluten is digested by luminal brush border -> AA’s and peptides
- *this includes gliadin peptide (doesnt get degraded any further)

2) in susceptible individuals, gliadin is delaminates by tissue transglutaminase and then binds to HLA-DQ2/8 antigens on APCs that are presented to CD4-Tcells
3) autoreactive T-cells in lamina propria then produce cytokines that contribute to inflammation and leads to antibody production against tissue transglutaminase and gliadin
4) although not confirmed, is believed that deamidated gliadin peptides induce epithelial cells to produce IL-15 and proliferation of autoreactive CD8+ cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the morphology of celiac disease?

A

usually best seen in the transverse duodenum or proximal duodenum

Shows:

  • high levels of T-lymphocytes
  • intraepithelial lymphocytosis
  • crypt hyperplasia
  • villous atrophy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Clinical features of pediatric celiac disease

A

Usually between 6-24 months of age

Classic symptoms:

  • irritability
  • abdominal distention
  • anorexia
  • diarrhea
  • failure to thrive
  • weight loss/muscle wasting

Nonclassic symptoms: (usually only seen in 10 yrs+)

  • abdominal pain
  • nausea/vomiting
  • bloating
  • constipation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Clincial features of adult celiac disease

A

Usually seen between ages 30-60 years of age

Symptoms:

  • anemia (iron or Vit. B12/B6 deficiencies)
  • diarrhea
  • bloating
  • fatigue
  • dermatitis herpetiformis (looks like herpes on extremities) (only seen in 10% thou)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are serologic tests of celiac disease

A

Most sensitive = presence of IgA antibodies to tissue transglutaminase

2nd most sensative = IgA/IgG antibodies to deamidated gliadin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the cancers associated to celiac disease

A

Most common = Enteropathy-associated T-cell lymphoma

2nd most common = small-intestine adenocarcinoma
- **often times will present with uncommon symptoms of celiac disease despite gluten free diet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Environmental enteropathy

A
Syndrome of 
- stunted growth
- impaired intestinal function 
- repeated bouts of diarrhea within 2-3 years of life 
Most common in developing countries 

is believed to be caused by malnutrition, however refeeding and/or vitamin supplements DONT fix this disorder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Lactase deficiency

“Lactose intolerance”

A

Gives rise to osmotic diarrhea in the presence of lactose in the intestinal lumen
- biopsies usually cant be used to determine deficiency

There are 2 types:

1) congenital = autosomal recessive disorder with mutations in the lactase gene.
- shows explosive diarrhea with watery stools and ab distention

2) acquired = down regulation of lactase gene usually after enteric viral or bacterial infections
- most common in natives, blacks and Chinese populations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Abetalipoproteinemia

A

Autosomal recessive disease which results in an inability to secrete triglyceride rich lipoproteins
- mutations in the MTTP protien causes enterocytes to be unable to export lipoproteins and free FAs through walls

Symptoms manifest in infancy:

  • failure to thrive
  • diarrhea
  • steatorrhea
  • **acanthocytic red blood cells “spur cells” are seen in blood smears
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Microscopic colitis

A

Idiopathic diseases that manifest with chronic non bloody watery diarrhea without weight loss

Two subtypes:

1) collagenous colitis: (seen primarily in middle aged women)
- presence of dense subepithelial collagen layer.
- increased number of lymphocytes
- mixed inflammatory infiltrates in lamina propria

2) lymphocytic colitis: (no preference)
- increases intraepithelial T-lymphocytes
- associated with celiac disease/autoimmune disease

17
Q

Infectious enterocolitis

A

responsible for 1 million deaths per year

Enterocolitis caused by numerous bacterial infections

Symptoms: (varies hard based on pathogen)

  • diarrhea
  • abdominal pain
  • urgency
  • perianal discomfort
  • incontinence
  • hemorrhages
18
Q

Vibrio cholerae

A

Comma-shaped, gram (-) primarily transmitted by contaminated drinking water especially warm water.

Pathogenesis:
- noninvasive disease that uses cholera toxin to interact with ADP ribosylation factors to ribosylate and activates Gsq = overstimulates adenylate Cyclase and over production of cholride ions into the lumen = diarrhea

Mortality rate for severe = 50-70% with hydration therapy

19
Q

Campylobacter jejuni

A

Gram (-), S-shaped bacteria pathogen
- Causes travelers diarrhea and is associated with poor cooking techniques, and contaminated water, milk

Pathogenesis:

  • *is associated with reactive arthritis (HLA-B27 susceptible patients only)
  • is poorly understood but dose induce net fluid loss and inflammation

Symptoms

  • watery diarrhea
  • flu-like symptoms
  • **15-50% of patients can develop dysentery

Tx = self limiting. Rehydration therapy for all and antibiotic therapy for dysentery or immunocompromised patients

20
Q

Shigella

A

Gram (-) bacilli that are non motile, non capsules.
- one of the most common causes of bloody diarrhea and seen in poor sanitized water and food

usually seen in children under 5 yrs since it is only really spread fecal-oral transmission weather directly or indirectly via water

Symptoms: (needs 1-7 day incubation)

  • fever
  • watery diarrhea (all)
  • bloody diarrhea (50-60%)
  • ab pain

Tx: self limiting, can use antibiotics if needed
- DONT use anti-diarrhea meds since they can prolong symptoms due to in ability to clear bacteria

21
Q

Complications of shigellosis

A

Reactive arthritis

HUS

22
Q

Salmonella

A

Gram (-) bacilli

  • non typhi = enterocolitis/gastroenteritis
  • typhi = enteric/typhoid fever

Infections are most common in young children and elderly

  • highest in summer and fall
  • transmission = contaminated foos, raw/undercooked meat and poultry/eggs/milk
23
Q

Typhoid fever

A

Only seen in salmonella typhi/paratyphi pathogens

Infects 30 million/yr worldwide

Initial phase Symptoms:

  • anorexia
  • abdominal pain
  • bloating
  • N/V
  • bloody diarrhea
  • “rose spots”
  • splenomegaly

Chronic phase symptoms:

  • all above
  • bacteremia
  • flulike symtpoms
  • typhoidal fever (slowly increasing fever for 2 weeks that gets super high (>104))

Diagnosis = blood cultures

24
Q

Pseudomembranous colitis

“Anti-biotic associated colitis”

A

Caused by D. Diff infections that often precedes widespread antibiotic use (since it kills good bacteria and lets C. Diff run unchecked)

Toxins released by C. Diff causes ribosylation of small GTPases (Rho) and leads to:

  • disruption of epithelial cytoskeleton
  • tight junction barrier loss
  • cytokine release
  • apoptosis

Other factors that increase risk of C. Diff:

  • elderly
  • hospitalizations
  • immunosupression

Symptoms:

  • abdominal cramping
  • watery diarrhea
  • fever
  • leukocytosis
  • shows fecal leukocytes

Tx= metronidazole or vancomycin antibiotic use

25
Q

Ascaris lumbricoides

A

A nematode that infects people from fecal-oral contamination
- penetrates intestinal mucosa -> liver and creates hepatic abscesses -> lungs to cause pneumonitis

Diagnosis = eggs in stool

26
Q

Strongyloides

A

Nematode that live in fecal contaminated ground soil and penetrates unbroken skin -> lungs -> trachea -> get swallowed into the stomach and small intestines

**unlike other nematodes, Strongyloides hatches within intestines and releases larvae that penetrate mucosa and induces autoinfections

27
Q

Necator Americanus and ancylostoma duodenale

Hookworms

A

Infection is initiated by larval penetration through the skin -> lungs -> trachea -> swallowed into stomach and intestines -> hatches in duodenum and attach to mucosa

a leading cause of iron-deficiency anemia

Detection of eggs in stools = diagnosis