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GI > Control of GI infections / GI pathogens > Flashcards

Control of GI infections / GI pathogens Flashcards

1
Q

what are most infections in GI related to? (4)

A
  • cross contamination of work surfaces/utensils
  • undercooking (insufficiency heat to kill pathogens)
  • improper storage of food (inadequate refrigeration)
  • re-heating food
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2
Q

what is clostridium Difficile (C. duffle) a common cause of?

A

= healthcare associated diarrhoea

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3
Q

how is C. difficile carried?

A

= as part of normal bacterial flora, particularly in elderly

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4
Q

describe the mechanism of action of C. difficile?

A
  • organisms produce 2 toxins
    = toxins A (enterotoxin)
    = toxin B (cytotoxin
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5
Q

source/vehicle of infection of C. difficile

A
  • presents in small numbers in bowel
  • infection occurs when antibiotics are prescribed that kill off normal competitive bowel flora and allows C difficile to overgrow
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6
Q

what are symptoms of C. difficile?

A
  • diarrhoea, sometimes bloody
  • abdominal pain
  • severe cases may causes progress to pseudomembranous colitis or bowel perforation
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7
Q

how would you manage C. difficile?

A

= depends on every

Less severe = oral metrondiazole
Severe = oral vancomycin (for everything else you would give vancomycin IV but not in C. difficile)

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8
Q

how do you prevent C. difficile?

A

= good anti-microbial prescribing is KEY
= avoid 4C’s and use narrow spectrum antibiotics

  • isolating patients, hand washing (NOT GEL) and cleaning of environment
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9
Q

what type of bacteria is C. difficile?

A

gram positive spore bearing bacillus

= the spores are more resistant to disinfectant

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10
Q

C. difficile what would you see?

A

= presence of pseudo membrane on surface of colon

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11
Q

how do you diagnose C. diff?

A

There is no one good lab test;
= screening test for presence of organism (GDH)
= if GDH positive, test for prince of toxin (Toxin A &B)
= toxin will remain positive after 12 weeks after having had C. diff

Results;
- screening type neg = negative result
- screening type positive = positive result
= screening test pos, toxins test negative - indeterminate result

= if repeat is indeterminate = clinical decision required

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12
Q

viruses that cause diarrhoea

A

rotavirus

norovirus

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13
Q

describe rotavirus

A

commonest cause of D&V in children < 3years

  • most children have it by 5
  • person to person spread
  • common in winter
  • high infectious dose of 100 particles to catch it (highly infectious)
  • survives in environment
  • billions shed of it in faeces when diarrhoea
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14
Q

what is a consequence of rotavirus?

A
  • decreased absorption of fluids and increased secretion in bowel = dehydration
  • post infection malabsorption = causing more diarrhoea
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15
Q

how is diagnosis of rotavirus done?

A

= PCR test on faeces

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16
Q

how do you manage it rotavirus?

A

= rehydration is key

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17
Q

when is norovirus very prevalent?

A

= winter committing disease

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18
Q

what age of people are more likely to get norovirus?

A

all ages = highly infectious

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19
Q

describe he infectiousness of norovirus?

A

= 5 billion viruses per gram of faeces

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20
Q

how is norovirus spread?

A

= faecal-oral/droplet routes of spread

  • person to person (or on contaminated food/water)
  • environment survival
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21
Q

describe the incubation of norovirus?

A

= short incubation pardon often < 24hours
- sudden onset explosive D & V, lasts 2-4 day
= vomiting leads to widespread contamination of environment = outbreaks

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22
Q

how do you diagnose norovirus?

A
  • PCR test for faeces specimen or vomit swab
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23
Q

how do you treat norovirus?

A

= rehydration, particularly in young and elderly

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24
Q

why do you need to stay off work/school for at least 48hours post symptoms?

A

= because even when you are asymptomatic sheeting still occurs up to 48ours after

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25
Q

when are patients most infectious?

A

= when symptomatic with diarrhoea

26
Q

when would diarrhoea indicate infectious?

A

= fevere

= QUICK onset

27
Q

when would a patient need a side room?

A

= C. difficile

= norovirus

28
Q

when does the patient need admitted to ID unit?

A

= salmonella

= E. coli 0157

29
Q

what are other non-diarrhoea infections that are spread by faecal-oral route that?

A

= hepatitis A&E
- resistant bacteria carried in GI tract e.g. vancomycin resistant enterococci, highly resistant gram negative organisms (CPEs)

30
Q

Lecture 2 - GI pathogens

A

Lecture 2 - GI pathogens

31
Q

True or false.

the gut is full of bugs.

A

True

32
Q

describe the lifecycle of bacteria?

A
  • introduced to new environment
  • established
  • grow and spread
  • has an impact
33
Q

what are the most important gram negative and positive bacteria in the large bowel?

A

Gram negative
= enterobacteriaecae
- E. coli
- klebsiella spp.

Gram positive
= enterococcus
e.g. E. faecalis

34
Q

what is the lifecycle of a pathogen?

A
  • exposure
  • adhesion
  • invasion
  • colonisation
  • toxicity
  • tissue damage and disease
35
Q

what is colonisation?

A

= establishment of microorganism on or within a host, may be short lived

36
Q

what are pathogens?

A

= any micro-organism with the potential to cause disease

37
Q

what is virulence?

A

= the likelihood of causing disease

- opportunistic or accidental pathogen

38
Q

what 4 tests could be done?

A

= microscopy: stool, urine, CSF, sputum, pus
= serology
= antien detection
= PCR/molecular studies

39
Q

what are the different periods involved in invasion by a pathogen?

A
  • incubation period (pathogen replicates in host)
  • prodromal period (early signs and symptoms)
  • illness period (clinical signs and symptoms)
  • convalescent period (signs and symptoms recede; person returns to health)
  • host may become chronic carrier of infectious agent
40
Q

what infections can arise in the abdomen?

A
  • peritonitis (primary & secondary)
  • oral infections
  • oesophagitis
  • gastritis, duodenitis
  • hepatitis, liver abces
  • cholecystitis, cholangitis
  • pancreatitis
  • small bowel
  • gastroenteritis, abscesses
41
Q

how do you classify bacteria organisms?

A

1) shape
- bacilli = enterobacteraecia
- cocci = streptococcus sp, enterococcus ep
- spirochete = helicobacter pylori

2) growth characteristics
- aerobic/anaerobic
= characteristics of growth
= biochemical reactions

42
Q

describe gram negative rod testing.

A 
enterobacteriecaea
- lactose fermenting
= e. coli
= klebsiella spp
= enterobacter spp
  • lactose non-formenting
43
Q

how do you identify bacteria?

A

1) macroscopic
- colony size
- shape
- pattern haemolysis

2) microscopic
- gram stain
- organism shape

44
Q

describe the microbiological tests for enterobacteriacaea?

A
  • ferment glucose
    = produces acid
  • blood agar
  • MacConkey agar
  • CLED agar
  • chromogenic agar
45
Q

describe enterobacteriaecaea?

A
  • gram negative
  • non-spore forming
  • grow on a variety of solid media
  • ferment sugars
  • facultative anaerobes mostly
  • motile or non-motile
  • increasing resistance
46
Q

how does enterobacteriaecaea cause disease?

A

1) motility
- flagella allows movement
- shigella and klebbiela are not mobile

2) colonisation factors
- fimbriae

3) endotoxin
- cell wall component

4) enterotoxin

47
Q

what is a far quicker method of testing bacteria?

A

MALDI-TOF

48
Q

what organisms are serotyping important for?

A
  • streptococcus B-hemolytic
  • streptococcus pneumonia
  • neisseeria meningitis
  • E. coli
  • Klebsiella
49
Q

gram positives in mouth

A
  • strep viridian’s
  • neisseria sp, anaerobes
  • candida sp, staphylococci
50
Q

gram positives in stomach/duodenum

A
  • normally sterile

= others cause no problems

51
Q

describe normal bowel flora in jejunum, colonn and bile ducts.

A

Jejunum
- small number of coliform and anaerobes

Colon
- large numbers of coliform, anaerobes and enterococcus faecalis

Bile ducts
- usually sterile

52
Q

what is a strict anaerobe?

A

= a bug that will NoT grow in the presence of oxygen

- clostridium sp, bactericides sp, and anaerobic cocci

53
Q

where are strict anaerobes present in large numbers?

A

= in bowel

54
Q

what is the most import anaerobe

A

bacteroids

55
Q

gram positives in mouth

A
  • strep viridian’s
  • neisseria sp, anaerobes
  • candida sp, staphylococci
56
Q

gram positives in stomach/duodenum

A
  • normally sterile

= others cause no problems

57
Q

describe normal bowel flora in jejunum, colonn and bile ducts.

A

Jejunum
- small number of coliform and anaerobes

Colon
- large numbers of coliform, anaerobes and enterococcus faecalis

Bile ducts
- usually sterile

58
Q

what is a strict anaerobe?

A

= a bug that will NoT grow in the presence of oxygen

- clostridium sp, bactericides sp, and anaerobic cocci

59
Q

where are strict anaerobes present in large numbers?

A

= in bowel

60
Q

what is the most import anaerobe

A

bacteroids

GI (43 decks)

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