Enteric Infections Flashcards

(53 cards)

1
Q

Define: secretory diarrhea

- what are the features?

A
  • Watery diarrhea w/o fever or with minimal fever.
  • Continues despite increasing intake of food and water
  • mid abdominal pain
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2
Q

Define: Inflammatory diarrhea

A
  • mucoid like diarrhea
  • accompanied by fever
  • may often be bloody and have WBC in the stool
  • lower abdominal and rectal pain
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3
Q

Where does secretory diarrhea originate in the GI tract

A

small bowel

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4
Q

What are 5 examples of causative pathogens of secretory diarrhea?

A
  1. Vibrio cholera
  2. Rotavirus
  3. E. coli (ST or LT)
  4. Norovirus
  5. Giardia
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5
Q

What are 5 examples of causative pathogens of inflammatory diarrhea?

A
  1. Shigella
  2. Campylobacter
  3. E. coli (EHEC/STEC)
  4. Entamoeba histolytica
  5. C. difficile
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6
Q

What are the two toxins that C. diff produces? Which is more pathogenic?

A
Toxin A (enterotoxin) and B (cytotoxin)
- Toxin B is more pathogenic
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7
Q

What are 2 medication types that increase risk for C. diff?

A
  1. broad spectrum antibiotics

2. PPIs

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8
Q

What is the diarrhea like with C. difficile?

A

watery and foul smelling (like a barn)

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9
Q

What is the leukemoid reaction?

A

phenomenon of an increase in WBC count that mimics leukemia but is due to infection
- common in C. diff

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10
Q

What is the treatment approach for C. diff?

A
  1. Stop unnecessary antibiotics
  2. Metronidazole (IV or oral) and Vancomycin (oral only)
  3. Stool transplant to replenish to replenish microbiota
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11
Q

what are 3 virulence factors that pathogenic E. coli have?

A
  1. Fibriae: allow for colonization
  2. Adhesions: allow for cell invasion
  3. Toxins: both endo and exo
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12
Q

Shiga toxin is an example for what kind of toxin?

A

Exotoxin = secreted

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13
Q

What is ETEC and what specific pathogenic adaptations does it have?

A

Enterotoxigenic E. coli

  1. fimbriae for attachment
  2. Heat labile (LT) toxin similar to cholera
  3. heat stable toxin (ST)
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14
Q

What is the clinical syndrome for ETEC diarrhea?

A

mild water diarrhea and nausea but no vomiting for 1-4 days

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15
Q

What is the pathogenesis of ETEC diarrhea?

A

ingestion of fecally contaminated food/water with 10^8-10 bacteria needed to cause disease

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16
Q

What is the treatment for ETEC diarrhea?

A

Oral rehydration

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17
Q

What are EHEC and STEC?

A

They’re the same thing

enterohemorrhagic e. coli and shigatoxin producing e. coli

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18
Q

What are the virulence factors specific to EHEC/STEC

A

The shiga toxin (A/B) toxin

  • acts on ribosomes to block protein synthesis leading to cell death
  • has preference for enterocytes and endothelial cells in the kidney
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19
Q

What is the clinical syndrome of EHEC/STEC?

A

vomiting, diarrhea (often bloody), and abdominal pain

for children: 5-10 days later can develop lethargy, anemia, oliguria = hemolytic uremic syndrome

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20
Q

What are the two forms of salmonella?

A

non-typhoidal and typhoidal

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21
Q

What are the forms of non-typhoidal salmonella? What kind of illness do they cause?

A

Enteritidis and thyphimurium

- usually not invasive, self resolving disease

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22
Q

What are the forms of typhoidal salmonella? What kind of illness do they cause?

A

Typhi and parathyphi

- cause invasive disease with fever and bacteremia which is fatal if not treated

23
Q

what are the typical reservoirs of non-typhoidal salmonella?

A

reptiles and chickens

24
Q

What is the clinical picture of non-typhoidal salmonella?

A

Acute diarrhea with fever and abdominal pain that resolves within 4-7 days

25
What is the reservoir of typhoidal salmonella?
human only
26
What are the clinical symptoms of typhoidal salmonella disease?
Not always diarrhea! Can be constipated - can lead to ileus and perforation Long fevers + rash, headache
27
Where can salmonella typhi reside in the body dormant
the gallbladder
28
What is the virulence factor of typhoidal salmonella?
Vi capsular antigen which prevents phagocytosis
29
What is the treatment for typhoidal salmonella?
antibiotics based on local resistance
30
What are 3 adaptations that H. pylori have to increase colonization in the stomach ?
1. urease: converts urea to ammonium to neutralize stomach acid 2. swimming ability: spiral shape + flagella 3. Adhesions to bind to epithelial receptors
31
H. pylori is the most common cause of gastritis and also causes what % of duodenal and gastric ulcers?
90% of duodenal ulcers | 70-80% of gastric ulcers
32
Who should you screen for H. pylori infection ?
1. anyone with dyspepsia symptoms 2. Anyone with gastric cancer, active or history of peptic ulcer disease 3. red flag sx: early satiety, bleeding, weight loss, dysphagia, odynophagia
33
What are the 3 tests available to diagnose H.pylori? What are the benefits/issues with each?
1. Urease breath test - highly sensitive and specific, can use to test for cure - false neg with recent PPI or antibiotics 2. serology - high sensitivity and easy to perform clinically - lower specificity = false + - still positive post treatment 3. Endoscopy + biopsy - highest sensitivity + specificity, can also diagnose cancer or PUD - false neg possible is GI bleed, recent PPI or antibiotics
34
What is the treatment for H. pylori? For how long?
"Triple Therapy" 1. PPI: Lansoprazole... 2. Antibiotics (pick 2) - clarithromycin - amoxicillin - Metronidazole - Tetracycline/doxy Need to do a urease breath test to confirm
35
What type of virus is Hep A? Where does it replicate?
Picornavirus | - replicates in hepatocytes
36
What is the transmission of Hep A ?
fecal oral
37
What is the incubation period of Hep A?
~ 28 days
38
What is the clinical presentation of Hep A?
Typically mild, self limiting illness - fatigue - nausea - diarrhea - abdo pain - fever Later develop: - jaundice, - pruritis - dark urine - pale stools
39
How common is fulminant liver failure with Hep A
Very uncommon (<1%)
40
What is the treatment for Hep A?
Supportive | - most people recover in about 2-3 months
41
Is Hep A a chronic infection?
No, once it is cleared you are seropositive and immune
42
Dramatic elevations in transaminase levels are hallmarks of...
Acute hepatitis infection | - A or B
43
Food poisoning is by definition...
disease caused by eating food that has been contaminated with bacterial TOXIN
44
What are two common species that cause "food poisioning?
1. Staph aureus: produces enterotoxin | 2. Bacillus cereus: commonly found in soil (rice) and its spores survive cooking and produce enterotoxin at room temp
45
What is the clinical presentation of food poisoning?
ACUTE onset nausea, vomiting, and upper GI pain within 1-6 hours of ingestion - more vomiting than diarrhea - resolves within 24 hrs
46
What kind of bacterial is clostridium botulinum
gram positive, spore forming anaerobic rod
47
What kind of toxin does clostridium botulinum produce?
neurotoxin | - binds SNARE proteins and prevents Ach vesicles from docking at cleft
48
What is the clinical syndrome of botulism poisoning in adults?
"The D's" - double vision - drooping eyelids - dry mouth - dysarthria - dizziness - dysphagia - descending flaccid paralysis - diaphragm paralysis
49
What is the clinical syndrome of botulism poisoning in babies?
"floppy" baby - hypotonia - constipation
50
What is an abdominal abscess?
A disruption of the bowel wall integrity that allows normal flora to exit into the peritoneum and cause disease
51
What is the management of an abdominal abscess?
surgical drainage and antibiotics 1. Piptazo or cefriaxone + metronidazole 2. surgical drainage with sample sent for culture at time of drainage
52
What are the two most common pathogens causing bowel abscesses?
E. coli and bacteroides
53
What other pathogens should you consider if a patient who is hospitalized with recent abx exposure develops a bowel abscess?
candida, enterococcus, and resistant gram negative bacteria