infectious diarrhoea Flashcards
diarrhoea
fluidity and frequency
gastroenteritis
3+ loos stools a day
accompanying feautures: abdo pain, fever, blood/mucous in stool
how is gastroenteritis caused
contamination of foodstuffs
poor storage of produce
travel-related infection
person-person spread
what is the most common pathogen causing food poisoning
campylobacter
which pathogen caused most food poisoning hospital admissions
salmonella
defences against enteric infections
hygiene esp hand washing stomach acidity normal gut flora gut immunity gastric motility age
different clinical presentations of diarrhoea
non-inflammatory/secretory e.g. cholera
inflammatory e.g. shigella dystentry
mixed e.g. C diff
non-inflammatory clinical presentation of diarrhoea
secretory - toxin mediated
frequent watery stools with little abdo pain
rehydration mainstay of therapy
mechanism of diarrhoea in cholera
secretory
increased cAMP results in loss of Cl from cells along with Na and K
osmotic effect leads to massive loss of water from gut
inflammatory diarrhoea clinical presentation
inflammatory toxin damage and mucosal destruction
pain + fever
bacterial infection/amboeic dystentry
antimicrobials may be appropriate but rehydration alone often sufficient
assessing patient with diarrhoea
symptoms and their duration
possible risk of food of poisoning - diet, travel history
assess hydration - postural BP, skin turgor, pulse
features inflammation - fever, raised WCC
how is hyponatraemia caused in diarrhoea patients
sodium loss with fluid replacement by hypotonic solutions
how is hypokalaemia cuased in diarrhoea patients
K loss in stools
investigations for diarrhoea patients
stool culture +/- molecular or Ag testing blood culture renal function blood count: neutrophilia, haemolysis abdo X-ray/CT is abdo distended/tender
treatment of gastroenteritis
oral rehydration with salt/sugar solution
IV saline
campylobacter gastroenteritis
up to 7 days incubation
can have severe abdo pain
salmonella gastroenteritis
symptoms usually <48hrs post exposure
diarrhoea usually <10days
post infectious irritable bowel common
e.coli gastrienteritis
typically have frquent bloody stools
produces shiga toxin
can cause haemolytic-uraemic syndrome
treatment supportive, antib not indicated
haemolytic uraemic syndrome
shigella toxin stimulates platelet activation, micro-angiopathy results
characterised by renal failure,, haemolytic anaemia and thrombocytopenia
when are antibiotics indicated in gastroenteritis
immunocompromised
severe sepsis or invasive infection
chronic illness e.g. malignancy
routine bacterial culture campylobacter
ieal temp 37-42C
lower 02 than air
commonest cause bacterial food poisoning UK
what does c.diff produe
enterotoxin (A) and cytotoxin (B)
is inflammatory
how is c.diff treated
metronidazole oral vancomycin fidaxomicin stool transplant ?surgery
preventing c.diff
reduce broad spectrum antib prescribing
avoid 4C antibs
isolate symptomatic patients
wash hands between patients w soap + watre
what are the 4C antib
cephalosporins
co-amoxiclav
clindamycin
ciprofloxacin
protozoa
1 cell animal
helminths
worms
how is parasitic diarrhoea diagnosed
microscopy
send stool with request ‘parasites, cysts and ova please’
UK parasites causing diarrhoea
giardia lamblia
cryptosporidium parvum
giardiasis dirrahoea
abdominal cramps, bloating nausea, bouts of watery diarrhoea, malabsorption, failure to thrive
treat with metronidozole
cryptosporidiosis diarrhoea
watery diarrhoea, nausea + vomiting, abdo cramps, low grade fever
no specidic treatment usually required, just rehydration
imported diarrhoea causing parasites
entamoeba histolytica
viral causes of diarrhoea
rotavirus
adenovirus
norovirus
how are rotavirus and adenovirus diagnosed
antigen detection: rapid test
how is norovirus diagnosed
PCR
