The normal microflora: an introduction

Abstract

The ‘normal microflora’ is the term most commonly used when referring to the microbial collection that consistently inhabits the bodies of healthy animals. Other terms used are ‘normal flora’, ‘commensals’ and ‘indigenous microbiota’. Of these, the strictly correct term is ‘indigenous micro-biota’, since it refers to a collection of microscopic creatures that are native to the body. ‘Flora’ and ‘microflora’ have an unfortunate botanical connotation. Commensalism refers to an association between two organisms in which one partner benefits from the relationship but the other obtains neither benefit nor harm. The normal microflora—animal relationship is not one of commensalism, however, since each partner influences the other markedly. Many scientists would prefer the use of ‘indigenous microbiota’ since it is more correct than the alternatives. ‘Normal microflora’ has, however, been used extensively in the medical literature for many decades, has international recognition, is likely to remain in common usage, and is therefore used in this book.