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Infectious, Epidemiology, Parasitology & Tropical Medicine > 21. Acute Infectious Diarrheal Diseases > Flashcards

21. Acute Infectious Diarrheal Diseases Flashcards

1
Q

List the bacterial organisms that cause invasive diarrhea

A
  • Shigella
  • Salmonella
  • Vibrio parahemolyticus
  • E.Coli (EHEC)
    -Staphylococcus aureus
  • Yersinia Enterolytica
  • Campylobacter jejuni
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2
Q

List the bacterial organisms that cause non-invasive diarrhea

A
  • Staph aureus
  • Clostridium perfringens
  • E.Coli
  • Vibrio Cholerae
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3
Q

List the causative agents of toxicogenic bacterial diarrhea and describe the common features of this type of diarrhea

A

WATERY DIARRHEA WITHOUT FECAL LEUKOCYTES
- S. aurues (room temp mayo, egg products)
- C. perfringens (rewarming precooked foods - church picnic diarrhea)
- E.coli ( traveller’s diarrhea - plasmid-mediated enterotoxin, many types - O157:H7 = uncooked beef)
- Vibrio cholera (epidemic cholera, secretory type of diarrhea)
- Bacillus cereus (reheated rice)
- C. botulinum (release of neurotoxin)

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4
Q

List the food items associated with Staphylococcus aureus diarrhea

A
  • mayonnaise (left out at room temp)
  • Egg-based products
  • Egg
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5
Q

Describe the treatment for Escherichia coli diarrhea

A
  • rehydration
  • cotrimoxazole (combination of sulfamethoxazole and trimethoprim)
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6
Q

State the antibiotic that shortens the duration of Vibrio cholerae diarrhea

A

Tetracycline

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7
Q

List the food items associated with Bacillus cereus diarrhea

A

rewarmed rice

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8
Q

Describe the clinical manifestation associated with Clostridium botulinum in an infant

A
  • Floppy Bbaby Syndrome - flaccid paralysis
    (neurotoxin is produced)
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9
Q

Describe the clinical findings of infection with Shigella

A
  • bloody diarrhea
  • fever
  • bacteremia
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10
Q

State the antibiotic used to treat Shigella

A
  • fluoroquinolone
  • 3rd gen cephalosporin
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11
Q

State the food associated with Salmonella and describe the diarrhea seen in this infection

A
  • poultry
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12
Q

Recognize the treatment for Salmonella infection

A
  • non bloody diarrhea
  • ciprofloxacin
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13
Q

State the bacteria that can cause diarrhea after ingestion of undercooked shellfish

A
  • Vibrio parahemolyticus
  • self-limited disease
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14
Q

State the toxin associated with enterohemorrhagic E. Coli and state the 2 clinical conditions associated with this infection

A
  • O157:H7
  • undercooked beef
  • bloody diarrhea
  • hemolytic uremic syndrome in a child - renal failure -> hemodialysis HUS/TTP
  • Abx not effective
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15
Q

State the treatment for Yersinia enterocolitica and state the disease this infection mimics

A
  • can mimic Crohn’s disease
  • can cause ankylosing spondylitis
  • co SMX-TMP
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16
Q

Recognize the bacterial infection that mimics ulcerative colitis

A

campylobacter jejuni

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17
Q

Recognize a complication of Vibrio vulnificus infection in a patient with cirrhosis

A
  • caused by raw shellfish or wound infection
  • produces necrotizing fascitis in cirrhosis
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18
Q

A patient presents with bloody diarrhea, and Shiga-like toxin is identified. An initial treatment of ampicillin did not decrease the symptoms. The doctor discusses the possibility of aplastic anemia and suggests the use of an antibiotic to treat virulent strains. Which antibiotic is the doctor referring to?

A

Chloramphenicol

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19
Q

What is the MOST common species of Salmonella in the US?

A

Salmonella typhimurium

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20
Q

A patient loves seafood and has shellfish for his dinner. He develops fever and vomiting. What is the probable cause?

A

Vibrio parahaemolyticus

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21
Q

A patient consumes an undercooked beef burger. Over the next few days, he has multiple episodes of bloody diarrhea. Which organism is the probable cause?

A

O157:H7 strain of Escherichia coli

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22
Q

A patient develops flask-shaped ulcers with hepatomegaly. He loves chicken to be part of his diet. The Widal test shows high titers. What is the probable organism?

A

Salmonella

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23
Q

A patient presents with increased creatinine levels and low platelets along with bloody diarrhea. Which organism is the probable cause?

A

O157:H7 strain of Escherichia coli

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24
Q

Which disease does Yersinia enterocolitica infection mimic?

A

Crohns disease

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25
Q

Which of the following complications is associated with Vibrio vulnificus in a patient with cirrhosis?

A

Necrotizing fasciitis

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26
Q

Recall which diarrhea-causing bacteria are most commonly found in beef, pork, poultry, and dairy products

A
  • Campylobacter Jejuni
  • Salmonella enterica
  • E coli O157:H7
  • Listeria monocytogenes
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27
Q

Recall which diarrhea-causing bacteria are most commonly found in seafood

A
  • Vibrio cholera
  • Vibrio parahemolyticus
  • listeria monocytogenes
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28
Q

Recall which diarrhea-causing bacteria are most commonly found in vegetables

A
  • Listeria monocytogenes
  • Shigella - green onions
  • E coli O157: H7 - leafy lettuce
  • Bacilus cereus - fried rice
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29
Q

Describe the non-pharmaceutical strategies used to treat dehydration associated with diarrhea

A
  • oral rehydration
  • water, salt, sugar
  • WHO recommendations
  • 3.5 g NaCL
  • 2 g trisodium citrate or 2.5 g Na HCO3
  • 1.5 g KCl
  • 20 g glucose or 40 g sucrose

homemade version -
1/2 tsp NaCl
1/2 tsp baking soda
4 tbsp sugar
1 litre water

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30
Q

List medications used to reduce diarrhea and their associated side effects

A
  • Bismuth subsalicylate
  • loperamide
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31
Q

Explain how loperamide can lead to complications if used to treat invasive diarrhea

A
  • one of the body’s clearing mechanisms is diarrhea
  • can slow down the clearance of these pathogenic bacteria
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32
Q

List the indications for antibiotic used to treat infectious diarrhea

A
  • wouldnt use it often
  • antimicrobial resitance
33
Q

List 3 antibiotics used to treat infectious diarrhea

A

-

34
Q

Identify patients with infectious diarrhea who are not optimal candidates for fluoroquinolone treatment

A
  • in adults with E coli O157
35
Q

Define infectious diarrhea

A

is the acute onset of excessive bowel movements caused directly or indirectly by microbial pathogens

36
Q

Recall the most common causes of domestic infectious diarrhea

A
  • campylobacter
  • salmonella
  • shiga-toxin producing E.coli (STEC)
  • Shigella
37
Q

Identify the signs and symptoms of diarrhea that warrant medical attention

A
  • profuse watery diarrhea with hypovolemia (volume depletion)
  • fever
  • > 48 hours
  • baby with diarrhea - low blood vol naturally
  • crohns disease or ulcerative collitis
  • severe abdominal pain
  • recent abx tx - clostridiodes difficile infection
  • immunocompromised patient
38
Q

List medications and underlying medical conditions that may cause diarrhea

A
  • chemotherapy (antimicrobials)
  • proton pump inhibitors
39
Q

Review the key exam findings in a patient with diarrhea that will guide your treatment approach

A
  • medications
  • sexual history
  • pets
  • onset (usually 2-7 hours) + vomiting predominant
  • recent food consumption
  • duration of symptoms
  • stool frequency and characteristics - frequent small volume stools containing blood and mucous - invasive pathogen
  • presence of severe abdominal pain
  • Physical exam:
    Volume depletion - decreased skin turgor, mucous membranes, orthostatic hypotension
    fever
    peritoneal signs - acute appendicitis
    (fever+ peritoneal signs + diarrhea = invasive pathogens)
40
Q

Discuss the indications for conducting a stool sample in a patient with infectious diarrhea

A
  • immunocompromised patienst
  • comorbidities - Crohns, diabetes
  • food handlers
  • health care workers
  • day care attendees
41
Q

Discuss the differential diagnosis of diarrhea

A

ischemic bowel disease
laxative abuse
partial obstruction
whipples disease
pernicious anemia
diabetes
malabsorption
small bowel diverticulosis
scleroderma
celiac sprue
ulcerative collitis
crohn’s disease

42
Q

Explain the classifications of diarrhea

A
  • watery diarrhea
  • Acute dysentery
  • Enteric fever
43
Q

Describe how the location of abdominal cramping in the setting of diarrhea may indicate the underlying cause

A
  • cramps in the umbilical region - small bowel cause of diarrhe a
  • below umbilicus - large bowel causes
44
Q

List the most common pathogens associated with watery diarrhea

A
  • vibrio cholera
  • Entertoxigenic E. coli (ETEC)
  • Enteropathogenis E.coli (EPEC)
  • Enteroaggregative E.coli (EAEC)
  • Diffusely adherent E.coli (DAEC)
  • Clostridium perfringens
  • Bacilus cereus
45
Q

What are the characteristics of watery diarrhea?

A
  • no fever
  • short incubation - 1-6 hours
  • preformed toxin
  • vomiting
  • longer incubation form - 8-16 hours
  • organism present in food - toxin after ingested
  • abdominal cramps
  • large volume diarrhea
  • occasional fecal incontinence
  • dehydration
46
Q

What does the stool culture look like in watery diarrhea?

A
  • no feal leukocytes
47
Q

What does an incubation period of 8-16 hours prior to the onset of profuse watery diarrhea indicate?

A

That the toxin was formed after ingestion of contaminated food.

48
Q

What is typically seen on stool exam in cases of watery diarrhea?

A

Absence of fecal leukocytes.

49
Q

Describe the pathogenesis of Vibrio cholerae

A
  • pathogen contains 2 subunits - A and B
  • A = active subunit
  • B = binding subunit
  • B subunit binds to GI epithelium of the small bowel
  • forms a pentameric ring and binds the toxin to an enterocyte receptor
  • GM1 ganglioside on mucosal cell surface
  • Forms a pore in the cell
  • Allows active component to get in
  • Toxin enters the endoplasmic reticulum
  • interacts with ADP ribosylation factor to activate the stimulatory protein Gsalpha
  • This stimulates the release of adenylate cyclase
  • an increase of cyclic AMP in cell
  • causes increase of Cl- ions into the cell
  • Na follows Cl
  • Massive watery osmotic diuresis
50
Q

Recite the signs and symptoms associated with cholera infection

A
  • severe frequent watery diarrhea (1L/hr)
  • gray, liquid stool without odour, blood, or pus
  • rice water stool
  • rapid dehydration - upto 6L/hr
  • loss of 10% of body weight
  • shock
  • death within 12 hours or less
    (even within 2-3 hours)
51
Q

Explain the treatment approach for cholera

A
  • rapidly replace fluids
  • mild infection: oral - 1 tsp NaCl, 4 tsp sugar per litre
  • IV Ringer’s lactate
  • Na, K, Cl ions in similar concentrations as plasma + some Ca 2+ & lactate

Antibiotics:
- Azithromycin
- Fluoroquinolone
- Doxycycline

52
Q

Which of the following describes the typical stool of a person infected with Vibrio cholerae?

A

Rice water appearance

53
Q

What is the function of the B subunit of the cholera toxin?

A

Creates a pore in the intestinal mucosal cell wall to allow active toxin to enter the cell

54
Q

What is the mechanism causing diarrhea in patients with cholera?

A

Secretes electrolytes into the gut lumen causing water to follow

55
Q

What is the mechanism of morbidity and mortality in patients infected by cholerae?

A

Hypovolemic shock

56
Q

What is the appropriate treatment for a patient suffering from severe cholerae?

A

Azithromycin and rapid intravenous electrolyte and fluid replacement

57
Q

What is the mechanism causing diarrhea in patients with cholera?

A

Secretes electrolytes into the gut lumen causing water to follow

58
Q

Describe the pathogenesis of enterotoxigenic Escherichia coli (ETEC)

A
  • Non-invasive form
  • Fimbrial adhesions -> intestinal colonization - brush border of the intestine
  • makes two types of toxins
  • Heat-labile enterotoxin and Heat stable enterotoxin
  • Heat labile (LT): works similarly to cholera, increases cyclic AMP -> watery diarrhea
  • Heat stable toxin (ST): increases cellular cyclic GMP -> watery diarrhea
  • plasmid-encoded
59
Q

Recall the signs and symptoms associated with ETEC

A
  • short incubation
  • Rapid onset of symptoms
  • nausea
  • vomiting uncommon
  • cramps
  • watery diarrhea - mild to severe
  • no blood
    -no tenesmus (rectal pain and urgency to defecate)
  • fecal incontinence
60
Q

Define tenesmus

A
  • rectal pain and urgency to defecate
    sign used to differentiate watery diarrhea from invasive colitis
61
Q

Describe the pathogenesis of enteropathic Escherichia coli (EPEC)

A
  • non-fimbrial adhesion
  • attatches to the epithelial cells and alters teh tight junctions between the cells
  • alters physiologic function
  • problems with ion transport
  • malabsorption
  • inflammatory response - causes apoptosis of cells and direct killing
62
Q

Recall the signs and symptoms associated with EPEC

A
  • common in newborns
  • low grade fever
  • Vomiting can be severe
  • watery diarrhea - changes in water and electrolyte secretion
63
Q

Differentiate between the bowel location more likely to be associated with watery diarrhea versus invasive diarrhea

A
  • invasive infections affect the colon
  • watery diarrhea - damage to microvilli or cell membrane of small intestine
64
Q

Explain the pathogenesis of Clostridium difficile

A
  • invasive
  • antibiotic-associated colitis
  • clostridium difficile
  • resistant to broad-spectrum antibiotics
  • overgrows in face of abx resistance
  • makes toxins that injure the colon
65
Q

A 28-year-old man is experiencing watery diarrhea with fecal incontinence, fatigue, and dehydration shortly after visiting the Caribbean. What is the MOST LIKELY pathogen causing this young man’s symptoms?

A

Enterotoxigenic E. coli

66
Q

Which of the following organisms causes osmotic diarrhea by increasing cellular cyclic GMP in the small bowel mucosal layer?

A

Enterotoxigenic E. coli

67
Q

How does heat-labile enterotoxin (LT) contribute to the watery diarrhea caused by Enterotoxogenic E. Coli?

A

Increases small intestinal cellular cyclic AMP production

68
Q

What is a distinguishing symptom of invasive colitis compared to non-invasive toxogenic diarrhea?

A

Tenesmus

69
Q

How does Enteropathogenic E. coli cause the disruption of tight junctions between intestinal epithelial cells?

A

Non-fimbrial adhesion to the epithelial cells

70
Q

Which of the following bacteria makes toxins that damage the colon?

A

Clostridium difficile

71
Q

Which of the following bacteria typically causes colitis due to overgrowth following, and sometimes even during, antibiotic therapy?

A

Clostridium difficile

72
Q

How does Enteropathogenic E. coli cause the disruption of tight junctions between intestinal epithelial cells?

A

Non-fimbrial adhesion to the epithelial cells

73
Q

How does heat-labile enterotoxin (LT) contribute to the watery diarrhea caused by Enterotoxogenic E. Coli?

A

Increases small intestinal cellular cyclic AMP production

74
Q

List the antibiotics that pose the highest risk of causing Clostridium difficile colitis

A

frequently linked - ampicillin, amoxicillin, cephalosporins, clindamycin, fluoroquinolones

infrequently - tetracyclines, sulfonamides, erythromycin, chloramphenicol, trimethoprim

rarely - aminoglycosides, metronidazole, vancomycin

75
Q

Recall the toxins that C. diff produces

A
  • spore forming pathogen
  • helps it to survive
  • disseminates
  • colonize a surface when antibiotics have altered their colonization resistance
  • effective barrier nursing is essential - isolate

3 toxins
- TcdA
- TcdB (x1000 more potent than A)
- Binary Toxin (CDT) - mild

76
Q

Explain the pathogenesis of C. diff

A
  • Effects of toxins ->
  • Glycosylate rhoB protein and inactivate GTPases
  • disruption of actin cytoskeleton
  • Disrupt barrier function of mucosa
  • Lead to apoptosis
  • provoke inflammatory response
77
Q

List the complications associated with C. diff infection

A
  • spectrum of disease depends on host susceptibility and immunity
  • virulence of c.difficile strain
  • timing and type of antimicrobial therapy

can lead to pseudomembranous colitis which can tehn go to fulminant colitis -> which can lead to toxic megacolon and death

78
Q

Recite the treatment options and routes of administration for C. diff colitis depending on the severity of infection

A

Infectious, Epidemiology, Parasitology & Tropical Medicine (11 decks)

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