CP23 - Gastroenteritis

Question 1

what are facultative organisms?

Answer 1

those that can grow in both aerobic and anaerobic conditions

Question 2

what are the benefits of gut flora?

Answer 2

metabolism
colonisation resistance for other bacteria
antibody induction eg. during allergies

Question 3

what factors affect the flora present in the gut?

Answer 3

diet

breast/bottle feeding

Question 4

what is the common flora found in the gut?

Answer 4

1. bactericides
2. prevotella
3. Clostridia
4. Bifidobacteria
5. enterobacteriacea
6. enterococci

Question 5

why are a lot of GI diseases associated with travel?

Answer 5

putting your normal gut flora in a different environment and having them encounter different substances can cause problems

Question 6

what are the common mechanisms through which bacteria cause gastroenteritis?

Answer 6

1. endotoxin production

2. Adherence

Question 7

which bacteria cause gastroenteritis by endotoxin production?

Answer 7

vibrio cholera - sporadic cases seen in returning travellers
E. coli
C. diff
Staph aureus - food poisoning
Bacillus cereus - spores can survive cooking. food poisoning can occur when meat cooked in advance and kept warm
C. perfringens

Question 8

which bacteria cause gastroenteritis by adherence?

Answer 8

shigella Sonnei and shigella flexneri - bacillary dysentry
E. coli
Campylobacter jejune -undercooked meat, both toxin and adherence
salmonellae - food poisoning, typhoid, paratyphoid

Question 9

what is bacillary dysentry?

Answer 9

infection of the intestines resulting in severe diarrhoea with the presence of blood and mucous in the faeces

Question 10

what is typhoid?

Answer 10

an infectious bacterial fever with an eruption of red spots on the chest and abdomen and severe intestinal irritation

Question 11

what is paratyphoid?

Answer 11

a fever resembling typhoid but caused by different but related bacteria

Question 12

what are the parasitic causes of gastroenteritis?

Answer 12

entamoeba
G. lambia
cryptosporidium

Question 13

what are the viral causes of gastroenteritis?

Answer 13

norovirus

rotavirus

Question 14

what is the epidemiology of gastroenteritis?

Answer 14

food borne diseases have reduced while non food borne diseases have increases in prevalence

Question 15

how does gastroenteritis present?

Answer 15

acute onset
D&V - ask for frequency, mucous, blood
abdo pain
systemic effects - fever etc.
other complications - dehydration, renal failure, haemolytic uraemia syndrome, toxic megacolon, Guillain-Barre syndrome, salmonella

Question 16

what facts are important to ask for if gastroenteritis is suspected?

Answer 16

travel history
food history
any unwell people they may be in contact with
immunotherapy
blood in stool

Question 17

how long does a GI infection last for in an otherwise healthy patient?

Answer 17

24 hours

Question 18

what investigations need to be done if a GI infection is suspected?

Answer 18

bloods - FBC, U&Es, CRP, cultures - only for disseminated infections
creatinine - a marker of infection
AXR if severe
assess stool for ova, parasites and cysts, microscopy

Question 19

what is viral gastroenteritis also called?

Answer 19

winter vomiting disease - caused by norovirus. common

Question 20

what are the symptoms of viral gastroenteritis?

Answer 20

diarrhoea, projectile vomiting

Question 21

how long does viral gastroenteritis last?

Answer 21

24-48 hours

Question 22

how is viral gastroenteritis usually managed?

Answer 22

no specific treatment
infection allowed to follow its course
lots of water to prevent dehydration
good hygiene to prevent spread
it is rarely dangerous

Question 23

what is cryptosporidiosis?

Answer 23

cryptosporidium infection
predominantly waterborne, because oocysts are resistant to chlorine based disinfectants like those found in swimming pools

Question 24

what are the effects of cryptosporidiosis on the body?

Answer 24

watery diarrhoea, mild to severe disease. most commonly in young children
no specific treatment

Question 25

what is the main virulence factor of E. coli?

Answer 25

shiga toxin

Question 26

what are the effects of shiga toxin?

Answer 26

premature destruction of RBCs, and these can then clog kidneys, causing haemolytic-uraemia syndrome

Question 27

what is the main species that produces shiga toxin?

Answer 27

shigella

Question 28

what is the mechanism of shiga toxin action?

Answer 28

1. activates g protein leading to increased levels of cAMP 2. activates ion channels 3. cells over-excrete chloride ions 4. water follows ions out of cells into the bowel 5. this can be up to 6L a day, rapid dehydration results

Question 29

what is the direct result of efflux of K or Cl ions from cells?

Answer 29

diarrhoea

Question 30

what are the 2 types of salmonella?

Answer 30

typhoidal - can disseminate | non-typhoidal - cannot disseminate

Question 31

how is gastroenteritis treated?

Answer 31

1. supportive management 2. avoid antibiotics, because they may increase the duration of salmonella carriage or may worsen HUS caused by E. coli 3. point 2 to be ignored if patient is at an extreme age, if the infection is caused by campylobacter or if the patient becomes septic

Question 32

what is antibiotic diarrhoea?

Answer 32

diarrhoea cause due to disruption of gut flora by antibiotics symptoms could range from mild diarrhoea to pseudomembranous colitis (toxic megacolon, perforation, shock) c diff infection can cause pseudomembranous colitis plaques

Question 33

what are the risk factors for c diff diarrhoea?

Answer 33

old age and primary illness

Question 34

which antibiotics put you at a high risk for C diff?

Answer 34

generally, the broader the spectrum,the greater the risk cephalosporins clindamycin

Question 35

which antibiotics put you at a medium risk of c diff?

Answer 35

``` ampicillin amoxicillin co-trimoxazole macrolides fluoroquinolones ```

Question 36

which antibiotics put you at a low risk of c diff?

Answer 36

``` ahminoglycosides metronidazole anti-psudomonal penicillins tetracyclines rifampicin vancomycin ```

Question 37

how are c diff infections treated?

Answer 37

antibiotics - oral metronidazole or vancomycin | faecal transplant - either faecal or oral route

Question 38

what are the benefits of faecal transplants?

Answer 38

c diff cycle is broken by repairing the problems with the gut flora increasing the diversity of the microflora in the patient's gut