Infectious Diarrhoea

Question 1

define diarrhoea

Answer 1

subjective

fluid and frequent stools

Question 2

define gastroenteritis

Answer 2

objective

3 or more loose stools per days and companying features

Question 3

define dysentery

Answer 3

obvious with large bowel inflammation and bloody stools

Question 4

what may cause gastroenteritis?

Answer 4

contaminated food e.g. chicken and campylobacter
poor storage of produce
travel related e.g. salmonella
person to person spread - norovirus

Question 5

what is the most common foodborne pathogen?

Answer 5

campylobacter

Question 6

what is the pathogen linked to the most hospital admissions?

Answer 6

salmonella

Question 7

commonest organisms causing gastroenteritis in scotland (3)

Answer 7

campylobacter
salmonella
e. coli O157

Question 8

what defences do we have against enteric infections?

Answer 8

hygiene
stomach acid
normal flora
immunity

Question 9

clinical features of non-inflammatory/secretory diarrhoea

Answer 9

secretory toxin mediated
frequent watery stools with little abdo pain
rehydration

Question 10

example of non-inflammatory/secretory diarrhoea

Answer 10

cholera

enterotoxigenic e. coli ETEC

Question 11

mechanism of diarrhoea in cholera

Answer 11

increased cAMP levels and Cl secretion

Question 12

example of inflammatory diarrhoea

Answer 12

shigella

dysentery

Question 13

clinical features of inflammatory diarrhoea

Answer 13

inflammatory toxin damage and mucosal destruction causing pain and fever
bacterial infection/amoebic dystenery
antimicrobials may be appropriate but rehydration alone often enough

Question 14

what may cause mixed non-inflammatory and inflammatory diarrhoea

Answer 14

C. diff

Question 15

assessing a patient with diarrhoea

Answer 15

symptoms and duration
risk of food poisoning
assess hydration
features of inflammation

Question 16

it is unlikely to be infective gastroenteritis if it lasts longer than?

Answer 16

2/52

Question 17

fluid and electrolyte losses in diarrhoea

Answer 17

These can be severe with secretory diarrhoea – 1-7l/day containing 80-100 mmol Na. Hyponatraemia
due to sodium loss with fluid replacement by hypotonic solutions. Hypokalaemia due to K loss in stool
(40-80mmol/l).

Question 18

investigations in diarrhoea

Answer 18

stool culture
blood culture
renal function
blood count - neutrophilia, haemolysis
AXR if abdomen distended and tender

Question 19

differential diagnosis for infective diarrhoea

Answer 19

IBD
spurious diarrhoea secondary to constipation
carcinoma

Question 20

diarrhoea and fever can occur with sepsis outside the gut. what make this more likely?

Answer 20

lack of abdo pain and tenderness goes against gastroenteritis
no blood or mucus in stool

Question 21

treatment of infective diarrhoea

Answer 21

rehydration
oral with salt/sugar
iv saline

Question 22

incubation period of campylobacter

Answer 22

7 days

Question 23

when will stool samples be negative for campylobacter?

Answer 23

6 weeks

Question 24

severity of abdo pain in campylobacter

Answer 24

severe

Question 25

post infection sequelae of campylobacter

Answer 25

Guillain-Barre syndrome | Reactive arthritis

Question 26

what makes it difficult to find a pathogen in stool cultures?

Answer 26

normal flora

Question 27

how long does it take to complete all tests in a stool culture?

Answer 27

3 days

Question 28

common strains of campylobacter

Answer 28

c. jejuni | c. coli

Question 29

how long after exposure do symptoms of salmonella develop?

Answer 29

<48 hrs

Question 30

how long does diarrhoea in salmonella gastroenteritis last?

Answer 30

<10days

Question 31

20% of patients with salmonella gastroenteritis will still have +ve stools after how long?

Answer 31

20/52

Question 32

what is prolonged carriage of salmonella associated with?

Answer 32

gallstones

Question 33

what condition is common after salmonella gastroenteritis?

Answer 33

post-infectious irritable bowel

Question 34

culturing salmonella

Answer 34

* Screened out as lactose non-fermenters then antigen and biochemical tests * Thousands of species with individual names * Genetically most are serotypes of the same species – salmonella enterica

Question 35

what salmonella species cause enteric fever and not gastroenteritis?

Answer 35

s. typhi and s. paratyphi

Question 36

how is e. coli O157 spread?

Answer 36

contaminated meat | person to person

Question 37

typical illness in e. coli O157

Answer 37

frequent bloody stools

Question 38

what does e. coli O157 produce?

Answer 38

verocyto toxin

Question 39

e. coli stays in the gut, where does the toxin go?

Answer 39

blood

Question 40

the e. coli O157 toxin can cause?

Answer 40

haemolytic uraemic syndrome

Question 41

what is HUS? and how to treat

Answer 41

characterised by renal failure, haemolytic anaemia and thrombocytopenia o Treatment supportive no antibiotics o Toxin binds to globotriaosylceramide o Platelet activation stimulated o Micro-angiopathy results o Attach to endothelial glomerular tubule and mesangial cells

Question 42

what other bacteria may cause diarrhoea?

Answer 42

``` shigella other forms of ecoli: enteropathogenic, enterotoxic, enteroinvasive staph aureus bacillus cereus clostridium perfringens ```

Question 43

when are antibiotics indicated for gastroenteritis?

Answer 43

``` immunocopromised severe sepsis or invasive infection valvular heart disease chronic illness diabetes ```

Question 44

clostridium difficile infection is commonly associated with what antibiotics?

Answer 44

clindamycin cephalosporins co-amoxiclav ciprofloxacin

Question 45

severity of diarrhoea in clostridium difficile

Answer 45

mild to severe colitis

Question 46

what does clostridium difficile produce?

Answer 46

enterotoxin and cytotoxin

Question 47

treatment of clostridium difficile

Answer 47

``` metronidazole oral vancomycin fidaxomicin stool transplant surgery ```

Question 48

prevention of clostridium difficile

Answer 48

reduce broad spectrum isolate symptomatic patients wash hands

Question 49

what parasites may cause diarrhoea?

Answer 49

protoza and helmonths giardia lamblia cryptosporidium parvum entamoeba histolytica

Question 50

parasite diarrhoea diagnosis

Answer 50

generally by microscopy

Question 51

where is girardia lamblia found?

Answer 51

contaminated water

Question 52

what does girardia lamblia cause?

Answer 52

diarrhoea, malabsorption, failure to thrive

Question 53

where may a vegetive form of girardia lamblia be found?

Answer 53

duodenal bioposy

Question 54

what is seen on stool microscopy of girardia lamblia?

Answer 54

cysts

Question 55

treatment of girardia lamblia

Answer 55

metronidazole

Question 56

where is cryptosporidium parvum found?

Answer 56

contaminated water - animal faeces

Question 57

what is seen on stool microscopy of cryptosporidium parvum?

Answer 57

cysts

Question 58

treatment of cryptosporidium parvum

Answer 58

none

Question 59

entamoeba histolytica causes?

Answer 59

amoebic dysentery

Question 60

long term complication of entamoeba histolytica

Answer 60

amoebic liver abscess - anchovy pus

Question 61

treatment of entamoeba histolytica

Answer 61

metronidazole

Question 62

causes of viral diarrhoea

Answer 62

adenovirus norovirus rotavirus

Question 63

most common cause of viral diarrhoea in children under 5

Answer 63

rotavirus

Question 64

how is viral diarrhoea diagnosed?

Answer 64

antigen detection

Question 65

when is viral diarrhoea most common?

Answer 65

winter

Question 66

where does norovirus commonly cause outbreaks?

Answer 66

hospital community cruise ships

Question 67

diagnosis of norovirus

Answer 67

PRCR