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Block G -- Infection > Dr. Karatzios -- Diarrhea > Flashcards

Dr. Karatzios -- Diarrhea Flashcards

1
Q

Definition of diarrhea (3)

A
  • Stool weight > 200 g/day
  • ≥ 3 loose or watery stools per day
  • Decreased conmsistency and increased frequency from an individual baseline
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2
Q

3 types of diarrhea and their duration

A
  • Acute: ≤ 14 days duration
  • Persistent (subacute): > 14 days duration
  • Chronic: > 30 days duration
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3
Q

7 effects of diarrhea

A
  • Dehydration (water loss)
  • Salt imbalances (esp Na+ or K+)
  • Acidoses (bicarb losses)
  • Hemorrhage (if dysentery)
  • Chronic anemia (hematochezia)
  • Malnutrition
  • Sepsis (due to perforation or bacterial translocation into blood)
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4
Q

10 bacterial pathogens causing infectious diarrhea in the developed world

A
  • E. coli**​
  • *Salmonella *spp.
  • *Shigella *spp.
  • Yersinia enterocolitica
  • Campylobacterer jejuni
  • Clostridium difficile
  • Clostridium perfringens
  • Listeria monocytogenes
  • *Vibrio *spp.
  • Bacillus cereus
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5
Q

2 types of E. coli causing diarrhea

A
  • Enterohemorrhagic (EHEC)
    • O157:H7
  • Enterotoxin (ETEC)
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6
Q

2 types of Salmonella spp. causing diarrhea

A
  • Non-typhi
  • Typhi
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7
Q

7 viral causes of diarrhea in the developed world

A
  • Calicivirus/Norovirus (Norwalk-like)
  • Rotavirus
  • Astrovirus
  • Coronavirus (SARS)
  • Adenovirus
  • HIV
  • Influenza virus (seen in pandemic 2009 strain)
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8
Q

8 protozoal causes of diarrhea in the developed world

A
  • Giardia lamblia
  • Cyclspora cayetansis
  • Cryptosporidium **spp.**
  • *Microsporidium *spp.
  • Isospora belli
  • Entamoeba histolytica
  • Dientamoeba fragilis
  • Blastocystis hominis
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9
Q

5 purely toxin-mediated bacterial pathogens causing diarrhea in the developed world

A
  • Enterotoxigenic E. coli (Traveller’s diarrhea)
  • *Staphylococcus aureus *enterotoxin
  • *Bacillus cereus *enterotoxin, among others
  • *Vibrio *spp
  • C. difficile
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10
Q

5 bacterial causes of infectious diarrhea in the **developing **world (or “imported” diarrhea)

A
  • Salmonella **typhi**
  • *Shigella *spp.
  • Entertoxigenic E. coli
  • Vibrio parahaemolyticus
  • Vibrio cholerae
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11
Q

4 viral causes of infectious diarrhea in the **developing **world (or “imported” diarrhea)

A
  • Norovirus
  • HIV
  • Influenza virus (2009 pandemic)
  • SARS Coronavirus
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12
Q

4 protozoal causes of infectious diarrhea in the **developing **world (i.e. “imported diarrhea)

A
  • Giardia lamblia
  • Entamoeba histolytica
  • Microsporidium **spp.**
  • Isospora belli
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13
Q

Usual origin of infectious diarrhea in North America

A

Viral

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14
Q

Visibly bloody stool in **North American **diarrhea is a good predictor for what kind of pathogen?

A

Bacterial (especially EHEC)

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15
Q

5 bacterial causes of dysentery

A

SSCYE

  • *Shigella *spp.
  • *Salmonella *spp.
  • Campylobacter jejuni
  • Yersinia enterocolitica
  • E. coli O157
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16
Q

Viral causes of dysentery

A

None really, except perhaps adenovirus in immune suppressed patients (i.e. BMT)

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17
Q

Parasitic cause of dysentery

A

Entamoeba histolytica

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18
Q

EHEC: type of bacteria

A

Gram negative enteric rods containing a toxin created by a viral plasmis inside the cell

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19
Q

Reservoir of EHEC

A

Mammalian GIT

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20
Q

Most common cause of acute kidney failure in children

A

EHEC

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21
Q

Describe the progression of EHEC infection

A
  1. Enteritis about 1 - 2 days after infection
  2. Lasts for about 5 - 10 days
  3. Usually self-limiting
  4. 2 - 7% develop Hemolytic Uremic Syndrome (HUS)
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22
Q

3 symptoms of EHEC enteritis

A
  • Severe cramps
  • Very bloody diarrhea
  • NO fever
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23
Q

Cause of HUS in EHEC

A

Shigatoxin

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24
Q

7 signs and symptoms of HUS in EHEC

A
  • Renal failure
  • Consumptive thrombocytopenia
  • Vascular hemolysis (shearing of RBCs called schistocytes/schizocytes)
  • Stupor
  • Confusion
  • Seizures
  • Worsens with antibiotic therapy (release of toxin)
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25
Q

Type of bacteria: *Salmonella *spp

A

Gram negetive enteric rods

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26
Q

Resrvoirs of *Salmonella *spp.

A

Poultry and reptile GIT

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27
Q

Describe the progression and symptoms of *Salmonella *infection

A
  • Need about 105 bacteria to cause disease
  • Diarrhea (usually bloody), abdominal cramps, and fever 2 days after infection
  • Lasts about 1 week
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28
Q

Most serious form of *Salmonella *infection

A

Typhoid fever

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29
Q

Cause of typhoid fever

A

*Salmonella enterica *serogroup typhi

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30
Q

9 signs and symptoms of typhoid fever

A
  • Dissemination to various organs (i.e. blood, liver, etc)
  • High fever
  • Stupor
  • Cramps
  • Bloody diarrhea
  • Blood sepsis
  • Fleeting rose spots on skin
  • Left shift leukopenia
  • Bradycardia
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31
Q

What is *Salmonella *infection recurrence linked to?

A

Presence of biliary stones

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32
Q

*Shigella *spp: Type of bacteria

A

Gram negative enteric rods

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33
Q

Only reservoir of *Shigella *spp

A

Primates

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34
Q

Describe the progression of *Shigella *infection

A
  • Need ~10 bacteria to cause disease
  • Symptoms 1 - 2 days after infection
  • Lasts about 1 week
  • Highly contagious
35
Q

7 signs and symptoms of *Shigella *infection

A
  • High fever
  • Stupor
  • Cramps
  • Dysentery (black currant, jelly-like stools
  • Seizures due to shigatoxin
  • Sometimes HUS
  • Reactive arthritis
36
Q

Campylobacter jejuni: type of bacteria

A

Curved gram negative enteric rods

37
Q

Reservoir of Campylobacter jejuni

38
Q

Most common cause of bloody diarrhea in a daycare setting and one of the most common causes of enteritis due to food poisoning

A

Campylobacter jejuni

39
Q

Describe the symptoms (3) and progression (4) of *Campylobacter jejuni *infection

A
  • Enteritis starting about 2 days after infection
    • Cramps
    • Diarrhea may be bloody
    • Sometimes HUS
  • Usually self-limiting; Lasts for about 1 week
  • Guillain-Barre syndrome after about 2 - 3 weeks
  • Highly contagious
40
Q

Yersinia enterocolitica: Type of bacteria

A

Gram negative enteric rod that loves iron (uses it as a growth factor)

41
Q

4 Risk factor for *Yersinia enterocolitica *infection

A
  • High iron states
  • Eating undercooked meat
  • Drinking unpasteurized milk
  • Fecal-oral contact
42
Q

Reservoir of Yersinia enterocolitica

A

Various mammals (zoonosis)

43
Q

Describe the general progression of *yersinia enterocolitica *infection (5)

A
  • Starts within a week after infection
  • Lasts 1 - 3 weeks
  • Sepsis and bacteremia in immune suppressed people
  • Different manifestations between young children and older children/adults
  • Post infectious arthritis
44
Q

3 manifestations of *yersinia entercolitis *in young children

A
  • Bloody diarrhea
  • Terminal ileitis
  • Mesenteric adenitis
45
Q

Manifestation of *yersinia enterocolitica *infection in older children and adults

A

Severe abdominal cramps that may mimic appendicitis (pseudoappendicitis)

46
Q

5 signs and symptoms of *Entamoeba histolytica *infection

A
  • Bloody diarrhea
  • Cramps
  • Fever
  • Abscesses if dissemination to liver, lungs and brain (often in immunosuppressed)
  • Amoeboma
47
Q

Define amoeboma

A

Large mass in intestine that can be mistaken for a tumor but is really a granuloma due to amoebic infection

48
Q

Cause of traveller’s diarrhea

49
Q

Describe the symptoms and progression of ETEC infection (traveler’s diarrhea)

A
  • Self-limtied disease
  • No fever
  • No systemic illness
50
Q

Describe the progression and symptoms of cholera (vibrio cholerae infection)

A
  • Severe explosive watery diarrhea (liters and liters lost –> deadly)
    • Rice water stool
  • Highly contagious
51
Q

When can *Vibrio vulnificus *be acquired?

A

After eatign shellfish or stepping on a stingray

52
Q

5 signs and symptoms of *Vibrio vulnificus *infection

A
  • Diarrhea
  • Vomiting
  • Skin blisters
  • Sepsis
  • Shock
53
Q

Describe the progression of *Listeria monocytogenes *infection

A

Watery diarrhea can progress to disseminated disease in immune suppressed people and pregnant women (CNS disease, bacteremia, still births)

54
Q

Clostridium difficile: type of bacteria

A

Gram-positive anaerobic rod that forms resistant spores (need to be WASHED off hands)

55
Q

Disease caused by C. difficile

A

C. difficile-associated colitis (CDAD)

56
Q

4 signs and symptoms of CDAD

A

Toxin-mediated (toxins A and B)

  • Watery diarrhea
  • Colitis
  • Pseudomembranous colitis
  • May progress to toxic megacolon (septic ileus of the colon)
57
Q

Why don’t babies <6 months get CDAD?

A

No receptors for C difficile toxins (develpo between 6 months and 1 year), therefore diarrhea in hospitalized children <6 months is NOT C. diff

58
Q

4 risk factors for CDAD

A
  • Healthcare
  • Antibiotic use
  • Debilitated conditions (old age comorbidities)
  • PPI’s?
59
Q

2 important viral causes of watery diarrhea

A

Rotavirus

Norovirus

60
Q

Most common cause of self-limited gastroenteritis (i.e. 24h stomach flu or “winter gastro”)

61
Q

Usual type of diarrhea caused by parasites

A

Protracted and chronic

62
Q

3 risk factors for parasitic diarrhea

A

Travel

Fecal-oral contact (i.e. contaminated food)

Immune suppression

63
Q

Why are the “sporas” (name them) significant causes to remember of parasitic diarrhea

A
  • *Microsporidium *spp
  • *Cryptosporidium *spp
  • Cyclospora cayetanensis
  • Isospora belli

WHY = need special staining to see them

64
Q

5 points of **initial **management of diarrhea

A
  1. Evaluate severity and duration
  2. Obtain history and physical exam
  3. Treat dehydration
  4. Report suspected outbreaks
  5. Determine whether it is:
    1. Community-acquired/traveler’s diarrhea
    2. Nosocomial
    3. Persistent
65
Q

3 points of management if diarrha is community-acquired or traveler’s diarrhea

A
  • Consider quinolone for suspected shigellosis in adults (fever, inflammation)
  • Macrolide for suspected resistant Campylobacter
  • Avoid antimotility or certain antimicrobial drugs if suspected STEC (afebrile, bloody diarrhea)
66
Q

2 points of management for nosocomial diarrhea

A
  • Discontinue antimicrobial if possible
  • Consider metronidazole if illness worsens or persists
67
Q

Viral, non-bloody diarrhea with vomiting (3 causes)

A
  • Norovirus (esp if 24 - 48 hours)
  • Adenovirus
  • Astrovirus
68
Q

Non-bloody viral diarrhea without too much vomiting

69
Q

Turnover in lab for stool culture

A

24 - 48 hours; final ID and sensitivity in 72 hours

70
Q

4 cases where stool cultures are UNHELPFUL

A
  • ETEC (self-limited traveler’s diarrhea)
  • Self-limited *Yersinia enterocolitica *infections
  • Self-limtied non-typhoid Salmonellosis
  • Diarrhea after 3 days in hospital (think C. diff)
71
Q

4 cases where stool cultures are HELPFUL

A
  • EHEC (development of HUS)
    • Use of antibiotics may worsen renal failure
  • Public Health purposes
    • Shigella spp
    • *Salmonella typhi, Vibrio cholerae, outbreak situation (Campylobacter *spp infections in daycares)
  • When treatment will help
  • Help in diagnosis of Guillain-Barre syndrome
72
Q

6 cases where stool culture should be sent as a diagnostic test

A
  • Severe diarrhea (i.e. bloody, extremely large quantity)
  • Immunocompromised patients
    • HIV, <3 months or >65 years age
  • Patients with comorbid conditions (i.e. renal failure)
  • Patients with IBD
  • Food handlers and health care workers (Public health purposes)
  • Patients with Guillain-Barre syndrome
73
Q

2 diagnostic techniques to detect toxins A and/or B

A
  • Enzyme immunoassay
  • PCR
74
Q

Only viral diagnostic test that is currently widely available and used

A

Rotavirus test

75
Q

4 points of diagnostic testing for parasitic causes

A
  • At least 3 stools are required (different bowel movements) since parasites and their eggs are shed intermittently
  • Usually iodine-based staining techniques (NOTE: not for the sporas)
  • Lab diagnosis based on morphology
  • Results depend on how fast lab technician can get to specimens (a few days)
76
Q

8 situations where antibiotics SHOULD be used to treat diarrhea

A
  • Suspected or confirmed typhoid fever
  • Salmonella typhi in stool specimen
  • Shigella spp
  • Campylobacter spp infection
  • Bacteremia with any bacterial pathogen
  • Traveler’s diarrhea
  • Symptomatic *C. diff *colitis
  • Parasitic-related diarrhea
77
Q

3 cases where Ciprofloxacin po/IV or Ceftriaxone IV are used as treatments

A
  • Suspected or confirmed yphoid fever
  • *Salmonella typhi *in stool specimen
  • *Shigella *spp
78
Q

2 treatment options for traveler’s diarrhea

A
  • Ciprofloxacin po
  • Azithromycin po
79
Q

3 treatments for symptomatic *C. difficile *colitis

A
  • Metronidazole (Flagyl) po/IV
  • Vancomycin po
  • Enema with “healthy” stool
80
Q

What to treat with the “sporas”

A

Since available treatments are not very good and they occur primarily in immunosuppressed patients, treat the immune suppression

81
Q

3 situations where you DO NOT give antibiotics as treatment

A
  • Suspected or proven EHEC infections
  • Well-looking and non-bacteremic non-typhi *Salmonella *spp
  • Bloody diarrhea and systemically ill patients
82
Q

Why don’t you give antibiotics in suspected or proven EHEC infection?

A

May worsen renal failure and HUS

83
Q

Why don’t you give antiobiotics for well-looking and non-bacteremic non-typhi Salmonellosis?

A

Risk for prolonged shedding of organisms

84
Q

Why not give antibiotics for bloody diarrhea and systemically ill patients?

A

Better to “flush things out” rather than let it fester in the intestines for potential invasion

Block G -- Infection (23 decks)

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