Bacterial
Ecoli and campylobacter - most common in UK
salmonella and C diff - rarer but impt
giardia and shigella - more common in tropics
Viral
Norovirus and rotavirus - as common as bacterial

Usually self limiting
If fever, dehydration - (tachycardia hypotension oliguria) for >5/7 - admit
Avoid Abs unless systemically ill which often occurs with salmonella

acute onset, loose / watery stool, frequency / urgency, Bristol stool chart 6or7

risk factors
overseas travel
consumption poultry, contact with puppies (campylobacter)
diabetes
use of gastric acid suppressors

campylobacter - bleeding and pain (clarithromycin if needed)
salmonella - long systemic prodrome
shigella - may get haemolytic uraemic syndrome , usually dysentery
e coli - maybe dysentery, different strains
c diff - prior abs use
giardia - contaminated drinking water, upper GI Sx, slow onset, bulky floaty stool
cryptosporidium - dairy farms
rotavirus - associated with severe  dehydration and under 5's