What single test is most effective in separating Klebsiella oxytoca from K. pneumoniae?

The most effective test for distinguishing Klebsiella oxytoca from Klebsiella pneumoniae is the indole test. Klebsiella oxytoca is known to produce indole, which is a metabolic byproduct formed from the breakdown of tryptophan, while Klebsiella pneumoniae does not produce indole. This characteristic allows for a straightforward differentiation between the two species.

In practical laboratory settings, performing the indole test involves adding Kovac's reagent to a culture and observing the development of a red ring at the top of the test tube, indicating the presence of indole. The presence of indole in K. oxytoca thus provides a clear and definitive means to separate it from K. pneumoniae, which is crucial for accurate identification and appropriate treatment options.