ABSTRACT
The use of culture as a diagnostic technique will be described in Chapter 10. It is the purpose of this chapter to discuss only the principles of enrichment culture. This is a technique that has been in use for more than 100 years.1 It consists of incubating a sample in a medium that encourages the growth of an organism of interest while inhibiting the growth of others. In this way, it can assist the technician in isolating pure colonies of microorganisms from mixtures in which the organisms represent only a very small percentage of the overall ora, and in which isolation by streaking may not be practical. In some cases, as in the isolation of salmonella, rst growing a sample in an enrichment culture is a necessary step to increase the small relative number of organisms usually found in the primary sample.2 While the use of enrichment broths in food and environmental microbiology has been demonstrated, their use in clinical microbiology has not fully been established.3
