Which bacterial characteristic can differentiate Enterobacter from Klebsiella spp.?

The ability to produce indole is a significant factor in differentiating Enterobacter from Klebsiella species. Enterobacter, particularly species like Enterobacter aerogenes, is commonly indole-positive, while Klebsiella species, including Klebsiella pneumoniae and Klebsiella oxytoca, are generally indole-negative or variable. This biochemical distinction can be essential in a microbiological laboratory when identifying these organisms, as indole production is tested using specific media that indicate the presence of tryptophanase, the enzyme responsible for converting tryptophan to indole.

Indole production results in a color change in the testing medium, offering clear visual confirmation of the organism's metabolic capabilities. Recognizing this difference assists healthcare professionals in correctly identifying and treating infections caused by these bacteria, as they may have varying virulence factors and antibiotic susceptibilities. Thus, the characteristic of indole production serves as a key differentiator between these two genera in clinical microbiology.