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

\