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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
What does ECEH cause?
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
What is E. coli entérotoxigénique?
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
What is *Yersinia enterocolitica?*
Rare Can present in two main ways: 1. Acute: pseudo-appendicitis 2. Chronic: mimic ileitis or ileocolitis (Crohns)
28
What is C. diff?
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
What are some C. diff risk factors?
* ATB use (quinolones) * Hospitalisation * IPPs --\> not 100% sure * Altered immunity * Age
30
How is C. diff dx?
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
How is CPM tx?
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
What is the main complication of "maladies infectieuses"?
**Dehydration** --\> goal #1 is to rehydrate the pt
33
What is WHOs rehydration solution?
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
Megacolon and perforation?
Rare complication that happens with more serious cases Ileal perforation --\> typhoid
35
Syndrome hémolytique urémique?
O157:H7 Hemolysis with atteinte vasculaire rénale/cérébrale
36
What is Reiter's syndrome?
Immune rxn a couple weeks after enteritis Leads to inflammatory arthritis (sometimes atteinte urétérale) HLA-B27 ex: campylobacter, salmonella, shigella, and yersinia
37
What is Guillain-Barré syndrome?
Autoimmune manifestation in the PNS After a campylobacter infection (usually)
38
What is *Cyclospora?*
Parasite Epidemic --\> infection alimentaire Usually caused by travelling (ex: Nepal)
39
What is *Giardia*?
Most frequent parasite found in NA Contamination: * Contaminated water in the Rockeys and Adirondacks * Preschools/daycares * Trips to the south/nordic countries
40
What are Amibas?
Usually affect the colon After trips to Africa and Asia Dx: * Fecal examination * Colonic biopsies
41
What are some common amibas?
Entamoeba histolytics: **pathogen** --\> requires tx E. gingivalis, E. hartmanni, E. coli, E. dispar: **not pathogens**
42
How are amoebas tx and what are the main complications?
Tx: metronidazole 1-3 weeks Complications: * Hepatic abcesses (fever, douleur abdo HCD, bilan hépatique perturbé) * Echo helps with identification
43
What are the most frequent chronic parasite infections? (3)
1. Giardia lamblia 2. Entamoeba histolytica 3. Blastocystis hominis
44
What is Candida albicans?
Flore intestinale ou fécale normale Aucun rôle pathogène au niveau du grêle/colon mais pathogène dans l'oesophage
45
What is intestinal tuberculosis?
Cause: * Swallowing contaminated pulmonary secretions * Ingesting infected foods (such as cows milk) Clinical presentation: inflammation of distal ileum Quite rare in industrialized countries
46
What is sprue tropicale?
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
What is Whipples disease?
Caused by Tropheyma whipplei (gram +) Classic presentation: digestive sx (diarrhea, weight loss, abdominal pain) with arthralgia
48
How is Whipples dx and tx?
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
Flore intestinale normale:
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
What is the role of intestinal flora?
Energy: metabolize sugar/fibre in the colon Digest exfoliative epithelial cells Probiotics and prebiotics were developed to foster these roles
51
How to protect host from infection or too many bacteria?
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
What is bacterial overgrowth (pullulation)?
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
How is malabsorption linked to overgrowth?
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
What pathologies are responsible for overgrowth?
Stenosis: empêche transit normal Formation sacculaire/segments exclus (ex: diverticulose ou chx) --\> harder to clean Problem with peristalsis Déversement exagéré de bactéries
55
How is overgrowth dx?
**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
How is overgrowth tx?
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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