A 30 year old farmer presents with the features of high fever, painful inguinal lymphadenopathy, vomiting and diarrhoea with hypotension. Which of the following stain will be helpful in making the diagnosis?
**Core Concept**
The patient's presentation is suggestive of bubonic plague, a zoonotic disease caused by the bacterium *Yersinia pestis*. The disease is typically acquired through the bites of infected fleas or direct contact with infected animals. The symptoms include fever, lymphadenopathy, and systemic symptoms like vomiting, diarrhea, and hypotension.
**Why the Correct Answer is Right**
Wayson's stain is a specific staining technique used to identify *Yersinia pestis* in tissue samples. The stain is a modification of the Gram stain and helps in visualizing the characteristic bipolar staining pattern of the bacteria. This is particularly useful in identifying *Yersinia pestis* in lymph node samples or tissue sections from patients with suspected bubonic plague. The bipolar staining pattern, also known as "safety pin" appearance, is a key diagnostic feature of *Yersinia pestis*.
**Why Each Wrong Option is Incorrect**
**Option B:** Neisser stain is used to identify *Neisseria meningitidis*, a different bacterium that causes meningococcal meningitis and sepsis. It is not useful in diagnosing bubonic plague.
**Option C:** Albes stain is not a recognized staining technique for identifying *Yersinia pestis* or any other bacterium.
**Option D:** McFadyean's stain is used to identify *Bacillus anthracis*, the causative agent of anthrax. While it is a specific staining technique, it is not used to diagnose bubonic plague.
**Clinical Pearl / High-Yield Fact**
Bubonic plague is a rare but serious disease in non-endemic areas. Early diagnosis and treatment with antibiotics are critical in preventing mortality. The disease can be prevented by avoiding contact with infected animals and taking measures to avoid flea bites.
**✓ Correct Answer: A. Wayson's stain**