The gut contains as many as 1,000 different species of microbes. Some of the more well-known intestinal pathogens include:
Salmonella and Campylobacter (which account for most cases of food poisoning in the UK) Clostridium difficile (a risk during and after antibiotics).
Particular types of Escherichia coli which can cause diarrhoea – although many strains can live harmlessly in the gut.