| Abstract: | This work deals with the identification of Listeria monocytogenes, a common opportunistic pathogenic bacterium. It has become important medically because incidence of infection by Listeria has increased over the last few years for unknown reasons. The 1980's have experienced several foodborne epidemics with significant loss of life in previously healthy populations. The procedure investigated employs fluorometric monitoring of bacterial enzyme reactions with a fluorochrome called 4-methyl umbelliferone (4-MU) to identify Listeria monocytogenes and differentiating it from other organisms with which it might be confused. The test proved to be a practical method of identifying L. monocytogenes and distinguishing it from all other bacteria assayed using two 4-MU substrates. Fluorescence spectrophotometers used to measure these reactions are common in diagnostic laboratories and not prohibitively expensive. The reagents used are also inexpensive, about 2 cents per sample for the substrates. This test is rapid, requiring only one hour to obtain results, and is very sensitive because of the strong fluorescence of free 4-MU. It is specific for the organism because it measures enzymes under the bacteria's genetic control, and the manipulations are very simple and suitable for automation. Implementation of this test would aid in diagnosis of listeriosis and possibly lower the high mortality rates through early specific treatment. It would be especially useful during epidemics when large numbers of samples from clinical, food and enviromental sources require immediate testing. |
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