The microflora in our intestines is a fragile ecosystem. In a 'healthy' person the approximately 1014 bacteria in the intestines live in balance. However, this balance can easily be disturbed by stress factors, like the use of antibiotics. Antibiotics are indispensable for the treatment of several diseases. Since antibiotics can destabilise the natural intestinal flora, the use of antibiotics can result in unwanted side effects such as antibiotic associated diarrhoea (AAD).