Diarrhoea, Diseases- Yr 3, Wk 1

Question 1

Give the “subjective” definition of diarrhoea

Answer 1

Fluidity and frequency

a change in bowel pattern that indicates diarrhoea

Question 2

Give the “objective” definition of gastro-enteritis

Answer 2

-Three or more loose stools/ day
-accompanying features
(to have a gastro-enteritis you don’t need a positive culture)

Question 3

Give some “accompanying features” of gastro-enteritis

Answer 3

abdominal pain, loose stools, vomiting

Question 4

Define Dysentery “obvious meaning”

Answer 4

Large bowel inflammation, bloody stools

dysentery is slightly dated- a lot of inflammation therefore a lot of abdominal pain

Question 5

What is the classic cause of dysentery?

Answer 5

Shigella

Question 6

Name the tool used to help when examining stool samples

Answer 6

Bristol stool chart

Question 7

What are the features of stool that are used when using the Bristol Stool chart?

Answer 7

Times and consistencies of motion and whether there are additional features such as blood or mucus

Question 8

What is another name for Gastro-enteritis (GE)?

Answer 8

food poisoning

Question 9

Give some different causes of GE

Answer 9

• Contamination of livestock
• Storage of produce (bacterial proliferation at room temp)
• Salmonella in outbreaks, also imported from abroad (contaminated eggs)
• Campylobacter in (apparently) isolated cases, also imported
• Person to person spread (norovirus)

Question 10

What is the most common bacterial organism that causes GE?

Answer 10

Campylobacter

Question 11

What is the number of cases of food poisoning each year and what is the most common cause?

Answer 11

500,000 cases

Poultry is the most common source

Question 12

Name 3 bacterial organisms that have been isolated as a cause of GE in Scotland:

Answer 12

1) Campylobacter
2) Salmonella
3) E. coli O157

Question 13

Tell us about E Coli

Answer 13

its not a massive number but important as due to its complications, higher mortality in the young and old

Question 14

Name some defences against enteric infections:

Answer 14

-Hygeine (most important defence to stop food contamination)
-Stomach acidity (antacids and infection) (if you cut out your stomach acid then you cut out your first line of defence against pathogens)
-Normal flora (Cl. difficle diarrhoea)
-Immunity (-HIV-salmonella)
(HIV and go abroad for some time may increase your risk of infection) (In sub-saharan africa- some of the first presentations of food poisoning may indicate HIV infection)

Question 15

Name 3 types of diarrhoea and give their causes:

Answer 15

1) Non-inflammatory/ secretory: eg cholera
2) Inflammatory: eg shigella dysentery
3) Mixed picture eg C. Difficile
(secretory- lots of fluid stools- cholera)
(inflammatory- bacteria causing damage and inflammatory response of the system)

Question 16

Describe non-inflammatory diarrhoea:

Answer 16

-secretory toxin-mediated
:cholera- increases cAMP levels and Cl- secretion
:enterotoxigenic E. coli (travellers’ diarrhoea)
-frequent watery stools with little abdo pain
-rehydration is main therapy (replaces losses)

Question 17

Give a place where a cholera outbreak may take place

Answer 17

refugee camp

Question 18

Describe cholera

Answer 18

toxin increases cAMP production and lots of frequent watery stools without abdominal pain- the toxin affects the way you transport chloride and sodium across the enterocytes

Question 19

What does the cholera toxin act on?

Answer 19

the cyclic AMP (salt shifting into the gut and it takes fluid with it)

Question 20

Describe inflammatory diarrhoea:

Answer 20

-inflammatory toxin damage and mucosal destruction (PAIN AND FEVER)
-bacterial infection/ amoebic dysentery
-antimicrobials may be appropriate but rehydration alone is often sufficient
(inflammatory- the organism causes inflam of the gut lining- inflam response- blood and mucus in stools and abdo tenderness

Question 21

How do you assess someone with diarrhoea?

Answer 21

• symptoms and their duration (>2/52 weeks then unlikely to be infective GE)
• Risk of food poisoning (dietary, contact, travel history)
• Assess hydration (POSTURAL BP, skin turgor, pulse)
• Features of sepsis (fever, raised WCC)

Question 22

At bedside, why is postural BP better to measure rather than suppine?

Answer 22

because early dehydration would present with a postural drop rather than suppine

Question 23

What does SIRS mean?

Answer 23

systemic inflammatory response syndrome

fever, tachycardia

Question 24

What are you looking for in a baby when assessing them for a diarrhoea related illness?

Answer 24

-sunken fontanelle
-sunken eyes and cheeks
-decreased skin turgor
-few or no tears
-dry mouth or tongue
-sunken abdomen
(in adults, drop in BP)

Question 25

What investigations could you do when assessing the patient?

Answer 25

-stool culture -blood culture -renal function test -blood count: neutrophilia, haemolysis -abdominal X-Ray if abdomen distended, tender (Fluid and electroylyte losses- Losing salt and replacing with water and so end up with hyponatraemia – hyponatriaemia when admitted with secretory diarrhoea Most valuable is stool culture Blood count- WCC and c-reactive protein high in abdo infections X-RAY- dilatation of the large bowel- toxic dilatation)

Question 26

Differential diagnosis in people with diarrhoea thats not an infective cause?

Answer 26

- Inflammatory Bowel Disease - Spurious diarrhoea: secondary to constipation - Carcinoma

Question 27

Give an example of a problem outside of the gut that presents with diarrhoea and fever and give some other characteristics of this disorder:

Answer 27

``` Answer: sepsis outside the gut -lack of abdo pain/ tenderness -no blood/mucus in stools (-lack of abdo pain goes against GE -any community acquired pneumonia can present with diarrhoea- they wont have abdo tenderness but may have other problems) ```

Question 28

List some treatments of Gastro-enteritis:

Answer 28

-rehydration; IV or oral :oral rehydration with salt/sugar solution :IV saline -Antimicrobials? -DO NOT GIVE ROUTINE ANTIDIARRHOEALS -Treatment of complications (salt and glucose is the most effective treatment in replacing salt and fluid loss in diarrhoeal illness as glucose absorption is accompanied by sodium absorption)

Question 29

What is the commonest cause of bacterial GE?

Answer 29

campylobacter GE

Question 30

Give some facts about campylobacter GE?

Answer 30

-Up to 7 days incubation so dietary history may be unreliable -Stools negative within 6 weeks -abdominal pain can be severe -<1% invasive -Post-infection sequelae: Guillain-Barre syndrome, Reactive arthritis (-Commonest cause of bacterial gastro-enteritis -Abdo pain can be very severe -Not an organism that gets into the bloodstream commonly -Positive blood culture should prompt you to consider a problem with patients immune system- eg HIV?)

Question 31

Describe routine bacterial culture:

Answer 31

-difficult to find pathogen in the midst of complex normal flora -selective and enrichment methods of culture necessary - variety of media and incubation conditions -takes 3 days to complete all tests (Stool is least sterile sample- lots of bacteria- most of which part of normal flora -Stool culture- selective culture- looking for 4 pathogens- pathogen in admist of normal flora -Selective- eg specific salts, specific temperatures -A lot of patients will be better by the time they give a positive result to the ward)

Question 32

Describe routine bacterial culture campylobacter:

Answer 32

-specialised culture conditions -C. Jejuni/ C. coli -commonest cause of bacterial food poisoning in the UK -Chickens, contaminated milk, puppies -isolated cases rather than outbreaks (close association with chickens (poultry), dogs are a source person to person spread of camplyobacter is rare but if there is an outbreak- usually a common contaminated source)

Question 33

Describe salmonella GE:

Answer 33

-symptom onset usually less than 48hrs after exposure -diarrhoea usually lasts less than 10 days -< 5% have positive blood cultures -20% of patients still have positive stools at 20/52 (prolonged carriage may be assoc with gallstones) -post-infectious irritable bowel is common (-Hard to differenciate between salmonella and camplyobacter -Symptoms usually begin a lot sooner than camplyobacter and diarhhoea lasts less than a fortnight -Longer than 2 weeks think something other than infective gastroenteriitis -Positive blood culture- underlying immune function problem? -Infective gallstones- remove gallbladder? -Infections GE- no control- toilet day and night -Post infective irritable bowel- doesn't’ keep you up during the night , weird bowel first thing in morning)

Question 34

Describe routine bacterial culture 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) (SALMONELLA SHOULDN'T BE ABLE TO FERMENT LACTOSE) (Most are part of group of salmonella enterica- food poisoning causing organisms)

Question 35

what are the 2 commonest isolates of salmonella infections in the UK?

Answer 35

Salmonella enteritidis and salmonella tmphimurium

Question 36

where do > 50% of these come from?

Answer 36

imported from abroad

Question 37

what organisms cause enteric fever (typhoid and paratyphoid) and not GE?

Answer 37

S. Typhi and S. Paratyphi | Salmonella can be associated with reptiles eg lizards, snakes

Question 38

Describe E.Coli O157

Answer 38

- typical illness characterised by frequent bloody stools - E.coli O157 produces verocytotoxin(s) - E.coli O157 stays in the gut but the toxin gets into the blood - toxin can cause hemolytic-uraemic (HUS) syndrome (haemolytic anaemia and renal failure)

Question 39

Some side notes on E.Coli O157

Answer 39

-Pathogen that causes gastro-E -Associated with complications -Common exam question -This is O not a zero -Lots of e coli in gut and lots of strains -This is not the one that causes UTI- this is a specific gut pathogen -Source is beef and other live stock- contaminated beef that’s not adequately cooked -Living in country or contaminated water supply by cattle manure -Salmonella has bloody stools -Severe abdominal pain -Frequent bloody stools with crampy abdo pain -Patient has a gram negative in blood culture- don’t say Ecoli 157 as it doesn’t get into bloodstream It causes problem because it produces a toxin and the toxin gets into bloodstream – causes problem with haemolysis, renal impairment -GE you start with diarhhoea- and to get this complication (common young, old, diabetes, malignancy) – if you get this comp- common in first 10 days of having diarrhoea Requires a small innoculum to cause infection – only need a few organisms to cause GE

Question 40

Describe Haemolytic-uraemic syndrome:

Answer 40

- Toxin binds to globotriaosylceramide - Platelet activation stimulated - micro-angiopathy results - attach to endothelial, glomerular, tubule and mesangial cells

Question 41

Why is E.Coli O157 cases common in Aberdeen?

Answer 41

Due to farming

Question 42

Name some other bacteria

Answer 42

-Shigella (4 species) - there have been outbreaks of SHIGELLA SONNEI in nurseries

Question 43

Give some other forms of E.coli that cause diarrhoea:

Answer 43

-enteropathogenic -enterotoxic (traveller's diarrhoea) -enteroinvasive ROUTINE DIAGNOSIS OF THESE E.COLI STRAINS IS NOT POSSIBLE - ONLY O157 IS EASILY DISTINGUISHED FROM "ORDINARY" E.COLI)

Question 44

How is Shigella found?

Answer 44

- imported or lab transmission | - highly infectious person to person- low innoculum- easily transmitted to vulnerable patients

Question 45

Give some OCCASIONAL causes of food poisoning outbreaks:

Answer 45

-Staph Aureus (toxin) -Bacillus cereus (re-fried rice) -Clostridium perfringens (toxin) ( Staph aureus can produce GE orgasisms – hand hygine of staff at a wedding venue bad and causes this -Perfringens is the organism that causes gas gangrene)

Question 46

When are antibiotics indicated in GE?

Answer 46

for: -immunocompromised -severe sepsis or invasive infection -valvular heart disease -chronic illness -diabetes NOT INDICATED FOR HEALTHY PATIENT WITH NON-INVASIVE INFECTION)

Question 47

When someone presents with Clostridium Difficile diarrhoea, what do they usually say?

Answer 47

They give a history of previous antibiotic treatment | -severity ranges from mild diarrhoea to severe colitis

Question 48

How do you treat Clostridium Difficile diarrhoea?

Answer 48

- metronidazole - oral vancomycin - surgery may be required

Question 49

Some additional information on C. Diff diarrhoea:

Answer 49

-Usually seen in patients with prior antibiotic treatment -The 4 c- antibiotics- knock out most of the patients bowel flora- no competition for nutrients and proliferate -C diff produces enterotoxin (A) and cytotoxin (B) -Treatment with Fidaxomicin -Treatment with Stool transplants -Damage to the colonocytes which gives you the disease process -Ironically, the treatment is with antibiotics- oral vancomycin only used in this- its not absorbed when given TO GI tract hence why can only be used in this severe infection C DIFF produces spores and the infection recurs)

Question 50

What is the severe end of C. Diff infection?

Answer 50

Pseudomembranous colitis

Question 51

C. Diff infection- what can be done to prevent it?

Answer 51

-Reduction in broad spectrum antibiotic prescribing -Avoid 4 Cs – cephalosporins, co-amoxiclav, clindamycin, clarithromycin -Antimicrobial Management Team (AMT) and local antibiotic policy -Isolate symptomatic patients -Wash hands between patients (its a preventable illness, ciprofloxacin should be added there as well -the spores are resistant to alcohol gel)

Question 52

C. Diff infection- what is the management?

Answer 52

- Stop precipitating antibiotic (if possible) - follow published treatment algorithm- oral metronidazole if no severity markers - oral vancomycin if 2 or more severity markers

Question 53

Parasitology- describe:

Answer 53

-Protozoa and helminths -diagnosis generally by microscopy -send stool with request "parasites, cysts and ova" P, C and O (the last point is the stages of the life cycle of the organisms)

Question 54

Talk about some UK parasites:

Answer 54

-GIARDIA LAMBLIA -contaminated water -diarrhoea, malabsorption and failure to thrive -vegetative form in duodenal biopsy or "string test" -cysts seen on stool microscopy -treat with METRONIDAZOLE (men who have sex with men are able to transmit these organisms) (kids- failure to thrive)

Question 55

More UK parasites:

Answer 55

-CRYPTOSPORIDIUM PARVUM -first recognised in AIDS -contaminated water (animal faeces) -cysts seen on microscopy -NO TREATMENT (-have to notify cases of this to the health protection team -contaminated water is the biggest risk- advise people to boil water to kill the parasite)

Question 56

Give some imported parasites:

Answer 56

-large range of possibilities -Entamoeba histolytica- amoebic dysentery -vegetative from in symptomatic patient - ("hot stool") -cysts seen in asymptomatic patient -amoebic liver abscess may be long term complication ("anchovy pus") -Treat with METRONIDAZOLE) (-find out where the patient has been to look for the parasite -Hot stool- one that has instantly come out of the patient and then they run to laboratory to analyse it)

Question 57

Give some characteristics of Viral Diarrhoea:

Answer 57

- rotavirus in children under 5 yrs - adenovirus (40/41) can cause it - common in winter - diagnosis by antigen detection - there now is a rotavirus vaccine in developing world

Question 58

Where are common places where viral diarrhoeal outbreaks occur?

Answer 58

hospital, community, cruise ships, schools

Question 59

How is norovirus diagnosed?

Answer 59

diagnosis by PCR

Question 60

Is norovirus infectious?

Answer 60

very infectious

Question 61

what needs to take place when a norovirus outbreak occurs?

Answer 61

strict infection control measures needed (ward closures common- staff and patients affected)

Question 62

(How is norovirus spread?)

Answer 62

aerosol spread- vomiting- the air around the vomit becomes contaminated with the particles