Final answer:
In an epidemic, a microbiologist may use phage typing to identify and trace strains of bacteria. This technique tests the bacteria's susceptibility to different bacteriophages, which is distinct from molecular techniques like PCR, which amplifies DNA for identification purposes.
Step-by-step explanation:
To identify and trace strains of bacteria in an epidemic, a microbiologist may use phage typing. This technique involves testing a bacterial isolate's susceptibility to various bacteriophages, which are viruses that infect bacteria. Each type of bacteriophage will only infect certain bacteria strains, providing a pattern that can be compared with known phage susceptibility profiles. Techniques such as the Polymerase Chain Reaction (PCR) are also vital molecular biology tools, commonly used to identify particular C. difficile strains through amplification of selected portions of prokaryotic DNA. However, PCR is not specifically designed for testing bacterial virus susceptibility, unlike phage typing.
Other molecular biology techniques like gel electrophoresis and Western Blot are also used for DNA/RNA analysis but are not directly used for testing bacterial isolates against different bacteriophages. Furthermore, biochemical tests, DNA/RNA analysis, and serological testing methods are the broader categories that include various techniques for bacterial identification in potential epidemic scenarios.