Consider the uninoculated lysine decarboxylase tube Would it

Consider the uninoculated lysine decarboxylase tube. Would it be acceptable to use uninoculated ornithine decarboxylase medium as a control for, say, lysine decarboxylase tests? Defend your answer.

Solution

Yes, it would be acceptable to use uninoculated ornithine decarboxylase as a medium for control for lysine decarboxylase. This is because the test is performed to differentiate between two bacterial strains, whether they are lysine positive or negative. The uninoculated ornithine decarboxylase medium will not be able to display the results which are required to differentiate between two strains and can be used as a control for the strains which gives a positive result. This means that, if the control sample color is present in any sample tubes then it is positive for lysine decarboxylase and there is no change in the color then it is negative for lysine decarboxylase. The color of the control tube will be purple due to the pH indicator.