An abbatoir worker presented with a pustule on his hand that progressed to form an ulcer. Smear is taken from the ulcer and sent to laboratory for investigation. Which of the following is the best stain to determine the causative agent of the ulcer

Ans. a. Polychrome methylene blue In an abattoir worker, a pustule on the hand that progressed to form an ulcer indicates the diagnosis of cutaneous anthrax. Staining it with polychrome methylene blue stain, called as Mc-Fadyean's reaction, makes presumptive diagnosis of the anthrax. "When blood films containing anthrax bacilli are stained with polychrome methylene blue stain for few seconds and examined under microscope, an amorphous purplish materialQ is noticed around bacilli. This represents the capsular material and is characteristic of anthrax bacillie. This is called the Mc-Fadyean's reaction."- Ananthanarayan 8/e p245