GI > Gastroenteritis > Flashcards

Gastroenteritis Flashcards

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1
Q

what are 3 crucially important pathogens?

A

1) campylobacter
2) salmonella
3) E. coli 0157

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2
Q

what are 6 GI infection risk factors?

A

1) malnutrition (micro-nutrient) deficiency
2) closed/semi-closed communities
3) exposure to contaminated food/water/travel
4) winter congregating/summer floods
5) age<5, not breastfeeding
6) older age

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3
Q

what are 4 other risk factors?

A

1) acid suppression
- yersinia enterocolitica, helicobacter pylori tolerant of acid
- C. difficile more common with acid suppression
- Vibrio cholera, non typical salmonella, campylobacter, E. coli

2) immuno-suppression
- salmonella, campylobacter, shigella shed for longer
- other organisms that are uncommon in immune competent

3) micro-biome

4) genetics
- IL8 promoter variant & servere C. difficile
- O blood group& vibrio cholera

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4
Q

what are 6 bacterial factors involved in GI infections?

A

1) adherence/attached to GI mucosa
2) cellular invasion
3) production of exotoxins
4) changes in epithelial cell physiology
5) loss of brush border digestive enzymes, and/or cell death
6) increased intestinal motility, next fluid secretion, influx of inflammatory cells, and/or intestinal haemorrhage

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5
Q

describe innocuous size that makes picking up GI infections likely.

A
  • low infectious doses make spread easier

- pH affects required dose

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6
Q

what is diarrhoea?

A

= >3 unformed stools/day
= no the cause
- exclude laxative use/abuse & use of drugs/stimulants

  • departure from normal bowel habits
  • use Bristol stool char
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7
Q

what is gastro-enteritis?

A

= inflammation of intestines, particularly colon, causing diarrhoea, associated with blood and mucosa

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8
Q

what are 2 examples of bacteria that could cause gastro-enteritis?

A
  • shigella

- campylobacter

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9
Q

what systemic things is gastro-enteritis associated with?

A
  • fever
  • abdominal pain
  • rectal tenesmus (sense of incomplete defaeceation)
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10
Q

describe the duration of gastro-enteritis?

A

acute duration < 2 weeks

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11
Q

if gastroenteritis affects the large bowel describe the volume affected?

A

smaller volume

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12
Q

what can mimic appendicitis and why?

A

= yersinia enterocolitica

- as it may invade mesenteric nodes

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13
Q

what 4 things does bacteria need to multiply?

A
  • Time
  • temperature
  • food source
  • moisture
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14
Q

what can survive adverse conditions?

A

= spores

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15
Q

what happens in the kitchen that promotes bacteria growth?

A
  • cross contamination of raw & cooked food
  • preparation food too far in advance
  • inadequate heating & cooling
  • contaminated environment & equipment
  • poor personal hygiene
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16
Q

what is gastroenteritis caused by?

A

= eating food contaminated with micro-organisms, toxins, poisons

e. g. bacteria, viruses, parasites
- invasion of tissue +/- toxin production

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17
Q

what effect does cholera have on volume of diarrhoea?

A

= large volume of diarrhoea

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18
Q

describe the history most commonly associated with gastroenteritis?

A
  • diarrhoea, blood, mucus, time course
  • other GI symptoms
  • travel, contacts = human and animal
  • food history = storage, re-heating, washing
  • age of patients
  • co-morbitidites
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19
Q

describe what infections would be common with foreign travel, recent camping, recent antibiotics, daycare exposure, exposure to raw seafood, anal sex, HIV positive status and outbreaks.

A

Foreign travel

  • travellers diarrhoea = enterotoxigenic E. coli
  • Southeast Asia = vibrio species
  • South America, Africa, Asia = rotavirus

Recent camping
= giardia
= aeromonas
= cryptosporidium

Recent antibiotics
= C. difficile

Daycare exposure
= rotavirus

Exposure to raw seafood
= non-cholera vibrio

Anal sex
= shigella
= campylobacter
= salmonella

HIV positive statua
= mycobacterium avium-intracellular complex, mixrosporidia, cytomegalovirus, giarida

Outbreaks

  • cruise ships = noro
  • contaminated water, food = salmonella, E. coli, campylobacter
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20
Q

what 2 bacterias have a short incubation time of 1-6hours?

A

1) bacillus cereus (gram + bacillus)
- starchy foods
- heat resistance spores
- profuse vomiting
- reheating rice

2) staphylococcus aureus (Gram + coccus)
- performed toxin in food, rapid absorption
- acts on vomiting centre in bran
- foods left in room tempt
- milk/meat/fish

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21
Q

what do all stooges get tested for?

A 
= salmonella 
= shigella
= campylobacter
= E. coli 0157
= cryptosporidium

All > 4years stools get;
= C. difficile

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22
Q

what are the 4 groups associated with Shigella sp?

A

group A
= S. dysenteriae

group B
= S. flexneri

group C
= S. boydii

group D
= S. sonnei

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23
Q

what does shiga toxins do?

A
  • binds to receptors on renal cells, RBC and others
  • inhibiting proteins synthesis
  • causes cell death
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24
Q

what toxin can produce E. coli?

A

= shiga-toxin producing E. coli

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25
what symptom is associated with E. coli 0157 infections?
= bloody diarrhoea | = bloody per rectum
26
describe how one would acquire E. coli 0157?
- very low infectious dose - food (raw milk, water) - person to person - animal contact = children and elderly at risk of complications
27
describe the incubation time for E. coli 0157?
= 1-14 days
28
what can E. coli 0157 produce?
= verotohxin (VTEC)
29
what is HUS?
= haemolytic uraemic syndrome (HUS)
30
what is HUS associated with?
- abdominal pain - fever - pallor - petechiae - oliguria - bloody diarrhoea
31
describe the cell count that would be found in HUS?
- high white cells - low platelets - low HB - red cell fragments - LDH > 1.5 - may develop after diarrhoea stopped
32
how would you investigate HUS?
- send stool cultures samples | - send U&E, FBC, film, LFT, clothing, urine, dehydrogenase
33
Gastroenteritis 2
Gastroenteritis 2
34
what are 4 other E. coli pathotypes?
1) enterotoxigenic (ETEC) 2) enteropathogenic (EPEC) 3) enteroinvasive (ELEC) 4) enteroaggregative (EAIC)
35
describe enterotoxigenic (ETEC).
- produces heat labile and heat stable toxin - heat stable toxin similar to choler and yersinia toxins - travel related
36
describe enteropathogenic?
``` - attaching and affecting lesions = no toxins, not invasive - synthesises, secretes & inserts its own receptor into cell membranes - non breastfed children - can be asymptomatic ```
37
describe enteroinnvasive?
= watery diarrhoea, rare dysentry - demonstrates invasion - sereny test
38
describe entero-aggregaive?
- travellers diarrhoea | - cryogenic, secretogenic, pro-inflammatory
39
``` True or false. All diarrhoea (blood or not) is infectious? ```
False.
40
describe the incubation times for campylobacter?
- 16-48hours
41
describe how campylobacter is spread?
- spread sporadically (rarely outbreaks) - food:poultry - small pathogen number - food, hygiene (raw poultry especially) - macrolide - less likely to spread person to person - invasive - pain, blood, fever = most common
42
what are some campylobacter human pathogenic strains (enteric)
- C jejuni subspecies jejuni - C jejuni subspecies doylei - Campylobacter coli - Campylobacter upsaliensis - Campylobacter lari - C fetus subspecies fetus - Campylobacter hyointestinalis - Campylobacter concisus
43
describe the incubation time for salmonella enteritidis?
= 12-48hours
44
how is salmonella enteritidis spread?
- food: poultry, meat, raw egg - animal gut, multiplies in food - toxin and invasion - D&V, blood, fever
45
describe the serotyping of salmonella?
- >1500 different types: group A to Z based on antigen of body (O antigen) = a serotype helps pinpoint source of infection = groups B, C and D are most commonly locally
46
describe the incubation time for listeria monocytogenes?
= 9-48hours
47
describe the incubation time for listeria monocytogenes?
= 9-48hours
48
describe the symptoms of listeria monocytogenes?
- fever - muscle aches - diarrhoea = pregnant women may have mild symptoms
49
how would one acquire listeria monocytogenes?
- unpasteurised milk products, deli counter
50
describe the invasiveness of listeria monocytogenes?
- 2-6weeks - immunosuppressed - aged > 50 - pregnant - meningitis/bacteraemia
51
what type of bacteria is listeria monocytogenes?
gram + rod
52
how is listeria monocytogenes spread?
- food borne transmission - mother to child - rarely other
53
describe monocytosis in listeria monocytogenes?
- extract of cell membrane causes monocytosis in rabies, rarely in humans - but 67% cases of listeria monocytogenes have neutrophils
54
what are 2 important viruses in viral gastroenteritis?
- rotavirus | - noravirus
55
describe rotavirus.
= most common cause in kids <3years - all kids get it before 5 - person to person, faecal oral spread (direct & indirect) - usually in winter - moderate fever - vomiting - diarrhoea - not bloody - selt limiting - lasts a week
56
describe the infectious dose of rotavirus?
= low infectious dose - 100-1000particles = faecal-oral - survives in environment - billions shed in faeces when diarrhoea - affects absorption & secretion in bowel
57
what may children with rotavirus have?
= post infection malabsorptions | - leading to more diarrhoea
58
what is the key to managing rotavirus?
= hydration
59
describe the rotavirus vaccine?
- oral - live attenuated - excreted in faeces - 2 doses = 2 and 3 months
60
describe norovirus?
= winter vomiting disease - affects all ages (HIGHLY infectious) = 5 billions viruses per gram of faeces - faecal-oral/droplet routes of spread - person to person - environmental survival on fomites for days-weeks
61
describe diagnosis and treatment of norovirus?
Diagnosis = PCR on stool, takes 6hours treatment = self-limiting (unpleasant) - hydration is key
62
describe diagnosis and treatment of norovirus?
Diagnosis = PCR on stool, takes 6hours treatment = self-limiting (unpleasant) - hydration is key
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