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Diseases > Diarrhoea, Diseases- Yr 3, Wk 1 > Flashcards

Diarrhoea, Diseases- Yr 3, Wk 1 Flashcards

1
Q

Give the “subjective” definition of diarrhoea

A

Fluidity and frequency

a change in bowel pattern that indicates diarrhoea

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2
Q

Give the “objective” definition of gastro-enteritis

A

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

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3
Q

Give some “accompanying features” of gastro-enteritis

A

abdominal pain, loose stools, vomiting

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4
Q

Define Dysentery “obvious meaning”

A

Large bowel inflammation, bloody stools

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

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5
Q

What is the classic cause of dysentery?

A

Shigella

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6
Q

Name the tool used to help when examining stool samples

A

Bristol stool chart

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7
Q

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

A

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

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8
Q

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

A

food poisoning

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9
Q

Give some different causes of GE

A
  • 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)
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10
Q

What is the most common bacterial organism that causes GE?

A

Campylobacter

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11
Q

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

A

500,000 cases

Poultry is the most common source

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12
Q

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

A

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

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13
Q

Tell us about E Coli

A

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

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14
Q

Name some defences against enteric infections:

A

-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)

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15
Q

Name 3 types of diarrhoea and give their causes:

A

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)

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16
Q

Describe non-inflammatory diarrhoea:

A

-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)

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17
Q

Give a place where a cholera outbreak may take place

A

refugee camp

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18
Q

Describe cholera

A

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

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19
Q

What does the cholera toxin act on?

A

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

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20
Q

Describe inflammatory diarrhoea:

A

-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

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21
Q

How do you assess someone with diarrhoea?

A
  • 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)
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22
Q

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

A

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

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23
Q

What does SIRS mean?

A

systemic inflammatory response syndrome

fever, tachycardia

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24
Q

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

A

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

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25
Q

What investigations could you do when assessing the patient?

A

-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)

26
Q

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

A
  • Inflammatory Bowel Disease
  • Spurious diarrhoea: secondary to constipation
  • Carcinoma
27
Q

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

A 
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)
28
Q

List some treatments of Gastro-enteritis:

A

-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)

29
Q

What is the commonest cause of bacterial GE?

A

campylobacter GE

30
Q

Give some facts about campylobacter GE?

A

-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?)

31
Q

Describe routine bacterial culture:

A

-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)

32
Q

Describe routine bacterial culture campylobacter:

A

-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)

33
Q

Describe salmonella GE:

A

-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)

34
Q

Describe routine bacterial culture salmonella:

A

-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)

35
Q

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

A

Salmonella enteritidis and salmonella tmphimurium

36
Q

where do > 50% of these come from?

A

imported from abroad

37
Q

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

A

S. Typhi and S. Paratyphi

Salmonella can be associated with reptiles eg lizards, snakes

38
Q

Describe E.Coli O157

A
  • 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)
39
Q

Some side notes on E.Coli O157

A

-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

40
Q

Describe Haemolytic-uraemic syndrome:

A
  • Toxin binds to globotriaosylceramide
  • Platelet activation stimulated
  • micro-angiopathy results
  • attach to endothelial, glomerular, tubule and mesangial cells
41
Q

Why is E.Coli O157 cases common in Aberdeen?

A

Due to farming

42
Q

Name some other bacteria

A

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

43
Q

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

A

-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)

44
Q

How is Shigella found?

A
  • imported or lab transmission

- highly infectious person to person- low innoculum- easily transmitted to vulnerable patients

45
Q

Give some OCCASIONAL causes of food poisoning outbreaks:

A

-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)

46
Q

When are antibiotics indicated in GE?

A

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

47
Q

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

A

They give a history of previous antibiotic treatment

-severity ranges from mild diarrhoea to severe colitis

48
Q

How do you treat Clostridium Difficile diarrhoea?

A
  • metronidazole
  • oral vancomycin
  • surgery may be required
49
Q

Some additional information on C. Diff diarrhoea:

A

-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)

50
Q

What is the severe end of C. Diff infection?

A

Pseudomembranous colitis

51
Q

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

A

-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)

52
Q

C. Diff infection- what is the management?

A
  • Stop precipitating antibiotic (if possible)
  • follow published treatment algorithm- oral metronidazole if no severity markers
  • oral vancomycin if 2 or more severity markers
53
Q

Parasitology- describe:

A

-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)

54
Q

Talk about some UK parasites:

A

-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)

55
Q

More UK parasites:

A

-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)

56
Q

Give some imported parasites:

A

-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)

57
Q

Give some characteristics of Viral Diarrhoea:

A
  • 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
58
Q

Where are common places where viral diarrhoeal outbreaks occur?

A

hospital, community, cruise ships, schools

59
Q

How is norovirus diagnosed?

A

diagnosis by PCR

60
Q

Is norovirus infectious?

A

very infectious

61
Q

what needs to take place when a norovirus outbreak occurs?

A

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

62
Q

(How is norovirus spread?)

A

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

Diseases (9 decks)

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