Introduction to Microbiology
Control of Microbial Growth
The control of microbial growth may involve sterilization, disinfection, antisepsis, sanitization, or degerming. Sterilization is the destruction of all forms of microbial life, with particular attention to bacterial spores. Disinfection and antisepsis both refer to destruction of microbial pathogens, although some organisms, such as bacterial spores, may remain alive. Disinfection refers to the destruction of pathogenic organisms on an inanimate (lifeless) object, such as a table-top, while antisepsis refers to that destruction on a living object, such as the skin surface.
Sanitization refers to the reduction in the number of pathogens to a level deemed safe by public health guidelines. Degerming is the physical removal of microorganisms by using such things as soaps or detergents.
Any chemical agent that kills microorganisms is known as a germicide. An agent that destroys bacteria is called a bactericide, one that kills fungi is a fungicide, and one that kills viruses is a viricide. A bacteriostatic agent prevents the further multiplication of bacteria without necessarily killing all that are present.
Among the conditions affecting the use of a germicide are temperature, the type of microorganism, and the environment. Germicides are more effective at high temperatures because the chemical breaks down at lower temperatures. Microorganisms vary in their susceptibility depending on such things as the composition of their cell wall, the presence or absence of a capsule, and the ability to form spores or cysts. The environment can affect the activity of a germicide, as, for example, when organic matter is present. This material shields microorganisms from germicides and often reacts with the germicide.
