Modification of the normal microflora

Abstract

The preceding chapters demonstrate that, far from being a benign collection of microbial associates, the normal microflora constitutes a considerable hazard to the well-being of the human host. Lurking on and within the human body are numerous microbial species that, although of low virulence, have the capacity to produce disease. These opportunistic pathogens require conditions to exist in the host that predispose to the abnormal spread and multiplication of the microbes before diseases become manifest. The predisposing factors upset the usual balance that exists between the host and the microflora (Chapter 1). Under these conditions, certain microbial species become the aetiological agents of diseases. These particular members of the normal microflora are a major source of morbidity in hospitals, resulting in increased suffering for patients and higher medical costs because of the necessity for additional patient treatment and care.