Chapter 58 : Laboratory Controls and Standards

Abstract:

Growing numbers of microbiology laboratories are turning to the wide array of molecular technologies and platforms that are becoming available. With these new systems comes the need for effective ways to gauge their accuracy and reproducibility. This chapter describes different types of controls, along with their design and their potential utility in molecular microbiology applications. Control materials may take the form of run controls, calibrators, or standards. Run controls are used in a number of different embodiments to monitor overall assay performance and to estimate analytical uncertainty. Regardless of the type of control or the final application, an ideal control, calibrator, or standard would be composed of a matrix that is similar to the specimen matrix being tested, and it would contain the agent being targeted in the intact, biological form in which it naturally occurs. While assay-ready control materials can be purchased from a number of vendors, the number of organisms and assays for which they are available is limited. Raw-material components for control construction are available for many analytes, but to use these materials, each laboratory performing a test would have to manufacture its own controls and design reaction specifications to detect the control targets. The concept of a range would imply use for quantitative assays only; however, even qualitative molecular detection methodologies often provide results that lend themselves to some type of quantitative or semiquantitative analysis.