GI infections and microbial toxins Flashcards
examples of common microbes that reside in the stomach (3)
- lactobacilli
- streptococci
- yeasts
examples of common microbes that reside in the small bowel (6)
- lactobacilli
- streptococci
- yeasts
- clostridia
- enterobacteriacae
- enterococci
if below biliary tree then it will be enterococci not strep
examples of common microbes that reside in the large bowel (6)
- lactobacilli
- enterococci
- protozoa (chilomastix, trichompnas)
- yeasts
what type of organisms outnumber facultative aerobes in the large bowel
anaerobes
what is gastroenteritis
inflammation of the stomach and intestinal mucosa
why do pre-formed enterotoxins in bacteria on food result in very acute onset symptoms
the body immediately reacts to the enterotoxins -> the bacteria doesn’t have to make them once in the body so can cause damage straight away
bacteria also remain and reproduce inside the bowel
examples of bacteria thatcause non-inflammatory diahorrea from the proximal small bowel
- S. aureus
- Bacillus cereus
- C. botulinum
- enterotoxinogenic
- E.coli
what is the mgx for life threatening C.diff infection
ORAL vancomycin and IV metronidazole
what bacteria enter the mucosa of the colon/distal small bowel from the crypts (5)
- shigella
- salmonella
- campylobacter jejuni
- yesinia enterocolitica
- enteroinvasive E.coli
what bacteria can pentetrate the distal small bowel and result in enteric fever (3)
- salmonella typhi !
- Y. enterocolitica
- campylobacter
can lead to bacteremia and eventually result in sepsis
what food items can samlonella sp generally occur in (4)
- raw eggs
- undercooked meat
- unpasteurised milk
- unpasteuristed soft cheese
what pathogens can arise in dirty water (3)
- cholera
- vibrio sp
- giardia
what organism is the commonest cause for guillian-barre in the UK
campylobacter jejenum
where does campylobacter jejenum multiply
in bile
what do shiga /shiga-like toxin cause to happen in the bowel
shedding of blood from the bowel -> blood diahorrea occurs
symptoms of GI infections (5)
- diahorrea
- vomiting
- abdo pain
- blood in stool
- systemic symptoms (fever, jaundice. neurological symptoms)
how do viruses cause diahorrea
induce cell lysis in order for the virus to spread around the body -> death of cell leads to loss of absorptive cells -> diminished absorptive capacity -> more water in stool
how to enterotoxins induce diahorrhea
- cause increased chloride ion permeability of the apical membrane of intestinal mucosal cells
- increased Cl- permability leads to leakage into the lumen, followed by sodium and water movement
- results in secretory diahorrea
why might campylobacter be ciprofloxacin resistant
due to excessive abx use in farming/vet medicine leading to resistant bacteria being ingested in meat
what microbe can cause lifelong gastritis aftering drinking from mountain streams
giardiasis
what is the MOA of entero-aggregative E.coli
aggregate together and form a biofilm that hampers normal function of the intestines e.g. absorption
what are examples of post GI infectious complications
- chronic diahorrea
- lactase deficency
- malabsorption syndromes (coeliacs, tropical)
- IBD
- Reactive arthritis
- HUS syndrome (haemolytic anaemia, thrombocytopenia) - shiga-producing bacteria
what is haemolytic uraemic syndrome (HUS)
a complication of an E.coli infection that results in cell death and haemorrhage
why must the organism causing gastroenteritis be checked prior to giving abx
if shiga toxin bacteria (E.coli) then giving abx that kills the bacteria may result in the shedding of all toxins at once causing HUS
what abx are commonly responsible for C.diff resistant infections
- clindamycin
- fluroquinolones
- b-lactams
what is a complication of C.diff infection
toxic megaclonon
what test should be done is protozoan/parasitic infection suspected (e.g. giardia)
stool OCP test (ova, cysts and parasite)
what bacteria is in undercooked rice
bacillus cereus
