Catalase negative member of the family Enterobacteriaceae is (NOT RELATED)
## Core Concept
The question tests knowledge of the biochemical characteristics of bacteria within the Enterobacteriaceae family, specifically focusing on catalase activity. Catalase is an enzyme that decomposes hydrogen peroxide into water and oxygen. Enterobacteriaceae are a large family of Gram-negative, facultatively anaerobic bacteria.
## Why the Correct Answer is Right
The correct answer, , is catalase-negative. This is a distinctive characteristic that helps in the identification of certain bacteria within the Enterobacteriaceae family. Catalase-negative bacteria lack the enzyme catalase and therefore cannot break down hydrogen peroxide. This feature is clinically significant for differentiating among bacterial species.
## Why Each Wrong Option is Incorrect
* **Option A:** Typically, members of the Enterobacteriaceae family are catalase-positive, which helps differentiate them from catalase-negative bacteria.
* **Option B:** This option might represent a bacterium with different biochemical properties but is not specifically known for being catalase-negative within the context provided.
* **Option C:** Similar to Option A, this might represent a catalase-positive bacterium or one with different characteristics not aligned with being catalase-negative.
## Clinical Pearl / High-Yield Fact
A key clinical pearl is that *Streptococcus* species, which are not part of the Enterobacteriaceae family but are mentioned for contrast, are generally catalase-negative. However, within the Enterobacteriaceae, *Shigella* and some strains of *Yersinia* can be notable for their negative catalase reaction or weak activity, but specifically, the focus here seems to align with identifying a catalase-negative member which might not perfectly fit common Enterobacteriaceae characteristics.
## Correct Answer Line
**Correct Answer: D. **