Question

____is the primary pathogen that causes classic bacillary dysentery.

• A. Shigella dysenteriae
• B. Bacillus subtilis
• C. Lactobacillus dysenteriae
• D. Vibrio cholera

Hint:

Mnemonic: Shigella = Shiga toxin = Stool with blood (Dysentery). Contrast this with Vibrio cholerae = Voluminous Watery stool.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the name of the bacterial pathogen responsible for causing a specific type of severe, bloody diarrhea known as bacillary dysentery (Shigellosis).

Step 2: Detailed Explanation:

• Shigella Species: Bacillary dysentery is caused by four species of the genus Shigella: S. dysenteriae, S. flexneri, S. boydii, and S. sonnei.

• Shigella dysenteriae: Among these, S. dysenteriae (specifically Serotype 1) is the most virulent. It produces the potent Shiga toxin, which causes severe mucosal damage in the colon.

• Symptoms: Classic bacillary dysentery is characterized by frequent, small-volume stools containing blood, mucus, and pus, accompanied by abdominal cramps and fever.

• Other Options:
- Bacillus subtilis (B): Generally non-pathogenic, used as a probiotic.
- Vibrio cholerae (D): Causes Cholera, which is "watery diarrhea" (rice-water stools), not bloody dysentery.
- Lactobacillus dysenteriae (C): This is a fictitious name; Lactobacillus are beneficial bacteria.

Step 3: Final Answer:
Shigella dysenteriae is the primary cause of bacillary dysentery.