9. Microbioloy Of The GIT Flashcards
Which parts of the GIT are predominantly anaerobic zones?
Parts of mouth (e.g. Between teeth & in tastebuds)
Small bowel
Colon
What is meant by ‘obligate anaerobes’
Microorganisms unable to survive in presence of oxygen (at least at atmospheric pressure)
Survive & thrive in absence of oxygen
Describe 6 beneficial roles that bacteria play in the human GIT
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)
Why is a wound from a human bite potentially serious?
Human mouth contains lots of bacteria (esp anaerobic).
Laceration (esp to joint) can = infection (& poss joint destruction)
Explain why someone with a prosthetic heart valve may receive prophylactic antibiotics when having their wisdom teeth removed
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
Whats the difference between septicaemia & bacteraemia
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)
What proportion of tonsillitis is caused by bacteria vs virus
30% bacterial
70% viral
Therefore consider antibiotics only in presence of Tonsillar exudates or signs of secondary pharyngitis
Mostly supportive treatment e.g. Hydration
Name a suitable prophylactic antibiotic regime for a patient with CD undergoing intestinal surgery
Metronidazole (to kill any anaerobic bacteria)
Gentamicin or Celhalosporin (broad spectrum agent to act on range of remaining bacteria)
How is Norovirus spread?
What is the normal incubation period?
What is the normal duration of symptoms?
Faeco-oral routs
Person to person contact via aerolisation of virus
1-2 days
1-3 days
What are the symptoms of Norovirus
Profuse vomiting (non-bloody, non-bilious) Watery diarrhoea (non-bloody) Abdominal cramps Headache Low grade fever
How would you assess whether someone with Norovirus is dehydrated?
Assess mucous membranes Skin turgor Sunken eyes Signs of Shock (in severe dehydration): tachycardia, tachypnoea Reduced passing of urine
What are the treatment options for Norovirus?
Just supportive measures: correct fluid & electrolyte intake
Define travellers diarrhoea
Production of 3 or more loose watery stools during/shortly after travelling abroad
Entero-toxigenic E Coli (ETEC) is a common cause of traveller’s diarrhoea. What type of bacteria is it?
Facultatively anaerobic gram negative rod
What type of of diarrhoea is commonly associated with ETEC (travellers diarrhoea)
Describe the mechanism by which this bacteria causes diarrhoea
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.
