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Bacteria – Back to the Basics case

Case of the Month: Bacteria – Back to the Basics

On any given day, clinical laboratories are confronted with bacteria which must be identified using a minimum of simple tests. GIDEON is designed to help design specific algorithms for any such organism. For example, let’s say that we have a Gram negative bacillus for identification. What is the best test to perform at this point? In the Microbiology module, indicate a positive result for “Gram negative” and “Bacillus or coccobacillus:”

In the Identication List window, a list of 657 compatible organisms appears:

Note that the order of taxa on this list is determined by relative probability of individual organisms in clinical laboratories, as well as the likelihood of encountering positive tests (Gram negative and Bacillus) in each individual taxon. As you might predict, Escherichia coli is most likely in both respects.

In order to determine the best test to perform at this point, merely mark all listed organisms using the top check box icon next to “Organism” and then press the button.

The following comparison chart will open in a new window:

This is an optimized list of discriminative tests which might be used at this point. In other words, the “best” tests are listed first:  Maltose, Glucose fermenter, Growth on MacConskey agar, etc.  If the organism in question is facultative, adding the latter to the list of tests in GIDEON will reduce the list of possible organisms from 657 to 233.

If at any point, you click on the individual organism names, screens will appear which detail the phenotype, former names, disease association, ecology and much more for any chosen organism. All screens, tables and charts can be printed out, sent to a word processor, PowerPoint, etc. For example, if we click on the blue name link for Escherichia coli, the following screen appears:

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