Topic 17: Rapid Identification Methods
- Identifiying bacteria must been done quickly and accurately.
- Accuracy is improved by using a series of standardized tests.
- The IMViC tests were developed as a means of separating members of the Enterobacteriaceae (enterics), particularly the coliforms, to determine whether water was contaminated with sewage.
- The IMViC uses a standard combination of four tests:
- I: indole production from trytophan
- M: methyl red test for stable acid production from glucose
- V: voges-proskauer test for production of acetonin from glucose (unstable acid production)
- C: use of simmons citrate as the sole carbon source
- Detects enterics - coliforms (- gram, bacillus)
- Rapid identification methods have been developed that provide a large number of results from one inoculation
- No culturing beyond the initial isolation is necessary with these systems.
- Comparisons between these rapid identification methods and conventional culture methods show that they are as accurate as conventional test-tube methods.
- Computerized analysis of test results increases accuracy becuase each test is a given point value.
- More important tests get more points.
- IMViC uses four tests of equal point value.
- Commericial identification systems provide a greater standardization in identification because they overcome the limitations of hunting through a key, preparing media, and evaluating tests within a laboratory or between different laboratories.
- save time, money, and labor
