All are true about Shigella except:
**Core Concept**
Shigella is a gram-negative, non-motile, non-sporing, facultative anaerobe that causes shigellosis, an infectious disease characterized by diarrhea, abdominal cramps, and fever. Shigella invades the colonic epithelium, leading to mucosal inflammation and fluid loss.
**Why the Correct Answer is Right**
Shigella enters the host through contaminated food or water, and the bacteria are then ingested. Once inside the host, Shigella colonizes the colon and invades the colonic epithelial cells using the Ipa proteins, which are injected into the host cell through a type III secretion system. This invasion leads to the formation of a pedestal-like structure, allowing the bacteria to remain attached to the host cell.
**Why Each Wrong Option is Incorrect**
**Option A:** Shigella is a gram-negative bacterium, which is true.
**Option B:** Shigella is known to cause severe diarrhea and abdominal cramps, making this option true as well.
**Option C:** Shigella is a non-motile bacterium, which is true.
**Clinical Pearl / High-Yield Fact**
Shigella infection can be prevented by proper hand hygiene, safe food and water handling, and avoiding close contact with infected individuals.
**Correct Answer: D.**