Chapter 12.3 : Molecular Methods for Identification of Cultured Microorganisms

Abstract:

Bacteria and fungi can be identified by using nucleic acid hybridization techniques. Nucleic acid probes can be used to confirm the identification of culture isolates that have been tested by presumptive identification methods. Alternatively, probes can be used as the primary method for identifying isolated organisms. Culture identification by probe hybridization is not dependent on the ability to detect minute quantities of nucleic acid, and thus sensitivity is not a limiting factor in this application of molecular technology. The advantage of probe-based identification is greatest for slow-growing organisms like the mycobacteria or for organisms for which convenient commercial identification systems are not available. Although the specificity of the available commercial probes is high and they facilitate rapid identification of a number of pathogens (Table 12.1-3), misidentifications do occur and serve to emphasize the need for caution in using any single characteristic in identification of a species. It should also be emphasized that at this point identification by probe hybridization is more expensive than conventional techniques for many organisms.