The GIDEON Tutorial

MICROBIOLOGY

Now that we’ve seen the drug, let’s look at the bug. As you remember, the cause of the Mongolian Mystery illness was identified as a facultative, gram negative bacillus. Let’s see how the computer can help us identify the organism.

In the Microbiology module, select the Identify tab next to Bacteria (upper left). Enter the following data using the left (positive) or right (negative) mouse buttons. As you do this, note that GIDEON knows enough to ‘neutralize’ irrelevant tests using a yellow sign. The organism in question was:

Gram negative +
Coccus -
Bacillus +
Facultative +
MacConkey agar +
Oxidase -
Catalase +
Glucose fermenter +
Motile -
Indole -
Voges Proskauer -
Citrate -
Hydrogen sulfide -

…now enter a negative ( – ) for all tests from Nitrate to Nitrate, Nitrite to gas, DNA’se, Esculin……through Phenylalanine deaminase. In the Fermentation or Acidification list, check Adonitol negative, Alpha methyl glucoside negative, L-Arabinose positive, Mannitol positive, Sucrose negative.

The resulting screen should look something like this:

Now you can see a list of probable organisms in the Identification List box:

This icon indicates that no information has been published regarding some of the tests we entered and the organisms in the list. Thus a positive/negative test cannot ‘rule out’ the relevant organism in these cases. The tests in question and other details are displayed when you Click on the organism name.