Contamination is the unwanted presence of a microorganism in a particular environment. That environment can be in the laboratory setting, for example, in a medium being used for the growth of a species of bacteria during an experiment. Another environment can be the human body, where contamination of various niches can produce an infection. Still another environment can be the solid and liquid nutrients that sustain life. A final example, which is becoming more relevant since the burgeoning use of biotechnology, is the natural environment. The consequences of the release of bioengineered microorganisms into the natural environment to the natural microflora and to other species that depend on the environment for their welfare, are often unclear.

The recognition of the adverse effects of contamination have been recognized for a long time, and steps that are now a vital part of...