9. Microbioloy Of The GIT Flashcards

0
Q

Which parts of the GIT are predominantly anaerobic zones?

A

Parts of mouth (e.g. Between teeth & in tastebuds)
Small bowel
Colon

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1
Q

What is meant by ‘obligate anaerobes’

A

Microorganisms unable to survive in presence of oxygen (at least at atmospheric pressure)
Survive & thrive in absence of oxygen

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2
Q

Describe 6 beneficial roles that bacteria play in the human GIT

A

Prevent colonisation of pathogens
Stimulate development of MALT
Stimulate production of natural antibodies
Kill non-indigenous bacteria
Assist in digestion of certain polysaccharides
Role in synthesising certain vitamins (B12, VitK)

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3
Q

Why is a wound from a human bite potentially serious?

A

Human mouth contains lots of bacteria (esp anaerobic).

Laceration (esp to joint) can = infection (& poss joint destruction)

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4
Q

Explain why someone with a prosthetic heart valve may receive prophylactic antibiotics when having their wisdom teeth removed

A

Mouth contains high concentration of bacteria.
Dental procedures can cause bacteraemia (bacteria in blood).
Can increase chances of prosthetic heart valve being colonised by these bacteria.
Prosthesis more easily colonised, leading to infection of endocardial surface if heart (infective endocarditis).
Prophylactic antibiotics reduce duration of bacteraemia

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5
Q

Whats the difference between septicaemia & bacteraemia

A

Septicaemia: clinically significant presence of microbes in bloodstream (infection not cleared quickly)

Bacteraemia: presence of bacteria on blood in absence of any clinical signs (any infection cleared quickly)

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6
Q

What proportion of tonsillitis is caused by bacteria vs virus

A

30% bacterial
70% viral

Therefore consider antibiotics only in presence of Tonsillar exudates or signs of secondary pharyngitis
Mostly supportive treatment e.g. Hydration

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7
Q

Name a suitable prophylactic antibiotic regime for a patient with CD undergoing intestinal surgery

A

Metronidazole (to kill any anaerobic bacteria)

Gentamicin or Celhalosporin (broad spectrum agent to act on range of remaining bacteria)

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8
Q

How is Norovirus spread?
What is the normal incubation period?
What is the normal duration of symptoms?

A

Faeco-oral routs
Person to person contact via aerolisation of virus

1-2 days

1-3 days

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9
Q

What are the symptoms of Norovirus

A
Profuse vomiting (non-bloody, non-bilious)
Watery diarrhoea (non-bloody)
Abdominal cramps
Headache
Low grade fever
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10
Q

How would you assess whether someone with Norovirus is dehydrated?

A
Assess mucous membranes
Skin turgor
Sunken eyes
Signs of Shock (in severe dehydration): tachycardia, tachypnoea
Reduced passing of urine
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11
Q

What are the treatment options for Norovirus?

A

Just supportive measures: correct fluid & electrolyte intake

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12
Q

Define travellers diarrhoea

A

Production of 3 or more loose watery stools during/shortly after travelling abroad

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13
Q

Entero-toxigenic E Coli (ETEC) is a common cause of traveller’s diarrhoea. What type of bacteria is it?

A

Facultatively anaerobic gram negative rod

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14
Q

What type of of diarrhoea is commonly associated with ETEC (travellers diarrhoea)
Describe the mechanism by which this bacteria causes diarrhoea

A

Watery without blood or mucus

Colonise mucosal surface of small intestine.
Use fimbral adhesions to bind enterocyte cells
Adhesion to mucosal epithelial cells allows transfer of enterotoxins produced from ETEC, stimulating release of liquid from cells lining intestinal walls.

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15
Q

Name 3 common causes of traveller’s diarrhoea

A

Entero-toxigenic E Coli (ETEC)
Shigella
Salmonella spp

16
Q

Name some gram positive cocci bacteria

Aerobic

A

Straphylococci
streptococci
enterococci

17
Q

Name some gram positive bacilli
Aerobic
Anaerobic

A
Aerobic:
Corynebacterium (diptheria)
Bacillus (anthrax)
Lactobacillus
Mycobacterium TB

Anaerobic:
Clostridia (tetani, perfringens, difficile)

18
Q

Name some gram negative cocci

Aerobic

A

Neisseria (meningitidis, gonorrhoae)

19
Q

Name some gram negative bacilli
Aerobic
Anaerobic

A
Aerobic:
E coli
Pseudomonas
Salmonella
Shigella
Vibrio cholera
Camylobacter
Helicobacter pylori
Haemophilus influenzae
Bordetella pertussis
Brucella

Anaerobic:
Bacteroides fragilis