This book is about the microbial species that inhabit the human body, and the consequences of the intimate relationships that we share with them. It is intended that the book will provide an introduction to the normal microflora for those studying disciplines within the health sciences, and for those in the food industry where interest in the microbiology of the digestive tract, especially with respect to lactic acid bacteria, is topical.

It has been estimated that there are more microbial cells inhabiting the human body than there are eukaryotic cells of which it is made up. This normal microflora usually co-exists relatively peacefully with the host and does not cause infection. The mechanisms by which this co-existence is achieved are still not properly understood and the interaction between the normal microflora and the host is far from simple. For a variety of reasons, however, this interaction can be disturbed and often results in the microflora becoming pathogens. The study of the diseases then caused is important both...