Gastroenteritis Flashcards Preview

Clinical Pathology > Gastroenteritis > Flashcards

Flashcards in Gastroenteritis Deck (27):
1

What are the most common commensal bacteria type in the gut?

Obligate anaerobes

Outnumber facultative anaerobic by 100 to one

2

What are the ebenficial effects of commensal bacteria in the guy>

metabolism
Colonisation resistance
Antibody induction

3

What are the main commensal bacteria in the gut?

-Bactericides sp
-Clostridium perfringens
- E coli
- Enterococcus faecalis

4

What are the key bacterial causes of gastroenteritis?

-Salmonella
-E coli
-C Diff
-Shigella
-V Cholerae
-Staph aureus
-Bacillus cereus

5

What are the main causes of gastroenteritis outbreaks in UK?

Foodbourne infections e.g. salmonella

Recreational water, e.g. swimming pools

Animal contact

6

What are the clinical presentation of gastroenteritis?

- Acute onset
- Vomiting and diarrhoea (freq, mucous, bloody)
- systemic effects e.g. fever
- Abdo pain
- Complications e.g. dehydration, renal failure, salmonella, toxic megacolon etc

7

What investigations are carried out in gastroenteritis?

Blood - FBC, U&E, CPR, cultures
- Stools - parasite/oocytes, microscopy, toxin e.g. C diff toxin, PCR - virus

8

Why are investigations in gastroenteritis difficult?

So many commensal bacteria, difficult to tease out causative bacteria

9

Whats the most common cause of viral gastroenteritis?

Norovirus

10

Why is norovirus a very successful pathogen?

Low infective dose, last on surfaces for long time, long excretion (faecal/oral route)

11

How is viral gastroenteritis spread?

Aerosols - vomiting and diarrhoea

12

What are the main parasites that cause gastroenteritis?

Cryptosporidium
Giardia
Entamoeba

13

How is cryptosporidium transmitted mostly and what adaptation does it have which makes it very resistant

Waterborne

Oocyte - resists chlorine

14

What are the two main routes by which bacteria cause infection?

Production of toxin
Adhesion/invasion of cell

15

What is the name for E. coli 0157?

Enterohaemorrhagic Ecoli

16

How does E coli 0157 cause symptoms?

TOXIN - Shiga toxin

17

Why is E coli 0157 particularly dangerous?

Can cause haemolytic uraemic syndrome (HUS) - can cause renal failure

18

What is the mechanism by which E coli causes diarrhoea?

Activates G protein which increase cAMP levels. This activates ion channels which causes an increased efflux of Cl ion. Osmotic gradient produced - diarrhoea/dehydration

19

How does salmonella cause infection?

Causes infection ITSELF (not toxin)

20

How is gastroenteritis treated?

Antibiotics avoided (wait it out/rehydration) can worsen symptoms/prolong carriage

21

How does antibiotic associated diarrhoea occur?

Disrupt normal microflora
- change in metabolism (CHO/bile acid)
- overgrowth of pathogenic bacteria

22

What conditions can antibiotic cause?

Diarrhoea
Pseudomembranous colitis
Toxic megacolon
Perforation
Septic shock

23

What is the main cause of pseudomembranous colitis?

C. Diff

24

What C diff strain is associated with deaths in younger individuals

CD027

25

What antibiotics are more associated with C diff infection?

4 C's
-ciprofloxacin (quinolones)

co-amoxiclav (broad spectrum penicllins,)

clindamycin

cephalosporins (3rd generation).

Fluroquinolones (CD027 strain)

26

What are the main antibiotics used for C. Diff?

Oral Metronidazole/
Vancomycin

27

Whats the best 'cure' for C diff?

Faecal transplants - restores commensal gut flora

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