A mucoid lactose fermenter isolated from sputum shows which of the following reactions: Motility Negative, Oxidase Negative, Citrate Positive?

The correct identification in this scenario is Klebsiella pneumoniae, which is known for its mucoid colony morphology due to the presence of a polysaccharide capsule. This significant characteristic is often highlighted in cases where mucus is produced, such as in sputum samples.

Klebsiella pneumoniae demonstrates a motility negative reaction because this organism is non-motile. In contrast, Escherichia coli, Enterobacter cloacae, and Proteus vulgaris are motile bacteria, which would exhibit a positive motility reaction.

The oxidase negative reaction aligns with Klebsiella pneumoniae, as it does not produce the enzyme cytochrome oxidase. On the other hand, oxidase positive bacteria may include some species of Pseudomonas or Neisseria, but none of the options provided, except Klebsiella, fits the criterion.

Citrate positive indicates that the organism can utilize citrate as its sole carbon source, which is characteristic of Klebsiella pneumoniae. While Enterobacter cloacae can also be citrate positive, the combination of mucoid lactose fermenting colonies alongside the specific biochemical reactions distinctly points toward Klebsiella pneumoniae in this case.

Overall, the combination of