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MD1 GI - EXAM 1 > Maladies infectieuses > Flashcards

Maladies infectieuses Flashcards

1
Q

What are the two main categories of infections?

A

Acute: a couple hours to a couple days

Chronic: over 2 weeks

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2
Q

What are the main causes of infections? (3+1)

A
  1. Bacteria
  2. Parasites
  3. Viruses

Sometimes mycoses… but not as common

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3
Q

What are the two main ways in which infections can be acquired?

A
  1. Ingesting contaminated food/water
  2. Transmission fécale/orale
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4
Q

What are the three main mechanisms in which infections work?

A
  1. Invasive:
    • ​​Destroys enterocytes
  2. Irritative:
    • ​​Destroys bordure en brosse (cell stays intact)
  3. Toxic:
    • ​​Stimulated cellular secretions due to the presence of a toxin
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5
Q

What does Vibrio cholerae stimulate?

A

Stimulates secretion by enterocytes:

  • Activate Cl CFTR canal –> causes a cascade… Na+ follow and then H2O
  • Dim. Na+ absorption –> sort d’eau
  • Inhibit NEH-2 and NEH-3 (échangeurs)
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6
Q

What does Vibrio cholerae cause?

A

Diarrhea which can lead to lethal levels of dehydration

Enterocytes can still absorb because toxins only target cellules sécrétoires

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7
Q

How does rotavirus work?

A

Inhibits the activity of disaccharidases on the bordure en brosse

Inhibits absorption through SGLT-1 transporters

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8
Q

How do bacteria/ZOT work?

A

Attack “jonctions serrées” and facilitates paracellular passage of toxins (agresseurs)

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9
Q

What are the most common clinical manifestations of infections?

A

Diarrhea (can be bloody)

Douleur abdocrampiforme

Fever

Vomiting

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10
Q

Which bacteria can cause bloody diarrhea? (4)

A

Shigella, Campylobacter, Salmonella, and E. Coli

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11
Q

What are the 4 kinds of viruses that can cause viral infections?

A

Rotavirus –> winter in temperate climates

Noravirus –> ex: Norwalk, during epidemics, or food poisoning

Adenoviruses

Astroviruses

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12
Q

Information about gastroentérite virale:

A

Transmission:

  • Fécale/orale
  • Aliments contaminés
  • Respiratory system (??)

Short term and self-resolving

No examination for identification

Dx: clinical and épidémie

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13
Q

Information about viral colitis:

A

Can be documented if caused by something such as CMV (cytomegalovirus)

Most commonly in pts that are immunosuppressed

Tx: with IV Ganciclovir

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14
Q

What are the types of bacteria that cause food poisoning (toxins)? (3)

A

Staph. aureus

Clostridium perfringens

Bacillus cereus

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15
Q

What are the sx of bacterial food poisoning?

A

Diarrhea and vomiting

2-12 hours post-ingestion

Self-resolving in a couple hours

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16
Q

What bacteria can cause diarrhea that persists for over 48 hours?

A

Campuloacter jejuni

Salmonella

Shigella

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17
Q

When should you do a fecal examination? (4 reasons)

A

Severe diarrhea

Diarrhea for more than 3-4 days

Bloody diarrhea

Epidemics

  • These tests don’t exclude a dx
    • only 3% chance if finding smt
  • Takes around 2-4 days to get a result
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18
Q

What bacteria can cause bloody diarrhea? (4)

A

Atteinte colique…

  • Campylobacter
  • Shigella
  • Salmonella
  • E. coli entéropathogène
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19
Q

What is Campyloacter jejuni ?

Contamination from?

Sx, Tx?

A

Gram - bacteria

Most frequent cause of bacterial enteritis

Contamination:

  • Uncooked chicken
  • Cross contamination

Sx: diarrhea w/ severe abdominal rxn

Tx: azythro or cipro (resistance starting to develop)

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20
Q

How can you contract Salmonella paratyphi ?

A

Contamination:

  • Contaminated chicken
  • Contact with exotic animals (turtles, lizards)
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21
Q

What is Salmonella typhi?

A

Rarer

Responsible for typhoid fever:

  • Often without diarrhea
  • Severe infection with fever (Typhoid fever)
  • Abdominal pain with atteine Iléeale
  • Hepatosplenomegaly
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22
Q

Salmonella in the vésicule biliaire:

A

Porteurs chroniques

Rechutes à l’occasion

tx: 4-6 semaines avec ATB –> essaye d’éradiquer

  • cholécystectomie au besoin pour éradiquer la source d’infection
    • usually in immunosuppressed patients
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23
Q

What is Shigella?

A

Very rare

It’s toxin is resistant to acid and very virulent which can cause epidemic eclosions

Risk factors?

  • Epidemics
  • Vacations
  • Homosexual relations
24
Q

What is E. coli O157:H7 (entérohémorragique)?

A

Toxine entéropathogène (shiga toxine)

Maladie de hamburger –> poorly cooked ground beef

Contamination:

  • Ground beef contaminated with fecal matter (destroyed when cooked)
  • Contaminated water
  • Fruit and veggies washed with contaminated water
25
Q

What does ECEH cause?

A

Bloody diarrhea (atteinte du colon transverse)

Can lead to “syndrome hémolytique urémique (SHU)”

  • Hemolysis and vascular complications mostly In kidneys and brain (hémodialyse PRN)

ATB –> increase in shigatoxin release so DO NOT USE THEM as tx for ECEH

26
Q

What is E. coli entérotoxigénique?

A

Different strain of E. coli that causes travellers diarrhea

  • Activates intestinal adenylate cyclase ou guanylate cyclase

Usually lasts 24-72 hours and causes 3-6 BM a day

  • If blood or fever… suspect another cause

Usually acquired in southern countries, Mexico, Antilles, India, etc..

Due to contaminated water/food washed with this water

Cannot be identified in fecal examinations

27
Q

What is Yersinia enterocolitica?

A

Rare

Can present in two main ways:

  1. Acute: pseudo-appendicitis
  2. Chronic: mimic ileitis or ileocolitis (Crohns)
28
Q

What is C. diff?

A

Can colonize the intestines –> asymptomatic

ATB can cause disequilibrium of flora which allows for proliferation and liberation of A OR B TOXINS –> TOXIC FOR GRÊLE AND COLON

Often quite severe and can be lethal

Called colite pseudo-membraneuse (CPM)

29
Q

What are some C. diff risk factors?

A
  • ATB use (quinolones)
  • Hospitalisation
  • IPPs –> not 100% sure
  • Altered immunity
  • Age
30
Q

How is C. diff dx?

A

E/p and questionnaire +++

  • Endoscopie: pseudo-membranes –> pathogneumonique for CPM
  • Fecal examination but you must specify you’re looking for it
    • ​Presence of bacteria is fine but its an issue if the toxin is present too
31
Q

How is CPM tx?

A

Prevention:

  • Use ATBs only when needed
  • Importance of hygeine
  • Use of probiotics

ATB to treat:

  • metronidazole po or IV
  • vanco po… IV will not get to intestines
  • fidaxomicin

IF severe case:

  • IV Immunoglobulins
  • Fecal transplant
  • Colectomie totale si réfractaire au tx médical
32
Q

What is the main complication of “maladies infectieuses”?

A

Dehydration –> goal #1 is to rehydrate the pt

33
Q

What is WHOs rehydration solution?

A

Oral rehydration therapy is a type of fluid replacement used to prevent and treat dehydration, especially due to diarrhea. It involves drinking water with modest amounts of sugar and salts, specifically sodium and potassium

34
Q

Megacolon and perforation?

A

Rare complication that happens with more serious cases

Ileal perforation –> typhoid

35
Q

Syndrome hémolytique urémique?

A

O157:H7

Hemolysis with atteinte vasculaire rénale/cérébrale

36
Q

What is Reiter’s syndrome?

A

Immune rxn a couple weeks after enteritis

Leads to inflammatory arthritis (sometimes atteinte urétérale)

HLA-B27

ex: campylobacter, salmonella, shigella, and yersinia

37
Q

What is Guillain-Barré syndrome?

A

Autoimmune manifestation in the PNS

After a campylobacter infection (usually)

38
Q

What is Cyclospora?

A

Parasite

Epidemic –> infection alimentaire

Usually caused by travelling (ex: Nepal)

39
Q

What is Giardia?

A

Most frequent parasite found in NA

Contamination:

  • Contaminated water in the Rockeys and Adirondacks
  • Preschools/daycares
  • Trips to the south/nordic countries
40
Q

What are Amibas?

A

Usually affect the colon

After trips to Africa and Asia

Dx:

  • Fecal examination
  • Colonic biopsies
41
Q

What are some common amibas?

A

Entamoeba histolytics: pathogen –> requires tx

E. gingivalis, E. hartmanni, E. coli, E. dispar: not pathogens

42
Q

How are amoebas tx and what are the main complications?

A

Tx: metronidazole 1-3 weeks

Complications:

  • Hepatic abcesses (fever, douleur abdo HCD, bilan hépatique perturbé)
  • Echo helps with identification
43
Q

What are the most frequent chronic parasite infections? (3)

A
  1. Giardia lamblia
  2. Entamoeba histolytica
  3. Blastocystis hominis
44
Q

What is Candida albicans?

A

Flore intestinale ou fécale normale

Aucun rôle pathogène au niveau du grêle/colon mais pathogène dans l’oesophage

45
Q

What is intestinal tuberculosis?

A

Cause:

  • Swallowing contaminated pulmonary secretions
  • Ingesting infected foods (such as cows milk)

Clinical presentation: inflammation of distal ileum

Quite rare in industrialized countries

46
Q

What is sprue tropicale?

A

Clinical presentation: diarrhea and malabsorption

Histology: partial atrophy of villosities (similar to celiacs)

Dx to consider mostly in endemic countries

Tx: tetracycline with folic acid

No identifiable pathogen

47
Q

What is Whipples disease?

A

Caused by Tropheyma whipplei (gram +)

Classic presentation: digestive sx (diarrhea, weight loss, abdominal pain) with arthralgia

48
Q

How is Whipples dx and tx?

A

Dx: duodenal biopsies

  • Atrophie vollositaire avec infiltration de la lamina propria par des organismes qui se colorent au PAS

Tx: ATB for many months

49
Q

Flore intestinale normale:

A

Tube digestif est stérile à la naissance mais colonisé par bactéries maternelles et alimentaires (36 000 espèces)

4 main groups of bacteria:

  1. Firmicutes
  2. Bacteroidetes
  3. Proteobacteria
  4. Actinobacteria
50
Q

What is the role of intestinal flora?

A

Energy: metabolize sugar/fibre in the colon

Digest exfoliative epithelial cells

Probiotics and prebiotics were developed to foster these roles

51
Q

How to protect host from infection or too many bacteria?

A

pH of gastric acid

Bile salts in the small intestine

Peristalsis

  • Phase 3 allows stomach and intestine to get rid of extra bacteria
  • If not working properly –> pullation actérienne intestinale
52
Q

What is bacterial overgrowth (pullulation)?

A

Increase in the normal bacteria found in the GI tract

    • 10 ^5 bacteria/ml
  • Anaerobic bacteria

Not due to the proliferation of a pathogen

53
Q

How is malabsorption linked to overgrowth?

A

Deconjugation of bile salts –> stops formation of “micelles” which prevents absorption of lipids and liposoluble vitamins

Atteinte inflammatoire de la muqueuse –> irregular villosities, deficit in dissacharidases

Consume B12, carbohydrates, and protein

54
Q

What pathologies are responsible for overgrowth?

A

Stenosis: empêche transit normal

Formation sacculaire/segments exclus (ex: diverticulose ou chx) –> harder to clean

Problem with peristalsis

Déversement exagéré de bactéries

55
Q

How is overgrowth dx?

A

Clinical presentation: diarrhea, malabsorption, weight loss, bloating, discomfort

Gold standard: aspiration of duodenal liquid (quite hard)

So instead… tests indirects fonctionnels

  • Bile salts marked with C13 or C14 –> pic d’excretion at 1-2 hours instead of 3-5 post-ingestion
  • Lactulose –> pic d’hydrogène at 1-2 hours instead of 3-5 post-ingestion
56
Q

How is overgrowth tx?

A

Correct the reason for why its happening and

Decrease intestinal bacteria with ATB: alternance et intermittence (not a bunch all at once for a long time)

MD1 GI - EXAM 1 (15 decks)

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