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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A man, after skinning a dead animal, developed a pustule on his hand as shown. A smear prepared from the lesion showed the presence of Gram positive bacilli in long chains which were positive for McFadyean's reaction. The most likely aetiological agent is :
assistant
The correct answer is  The history (animal contact), clinical picture (pustule in the area of contact) and lab findings (gram positive bacilli in chains with McFadyean reaction positive) are all characteristic of infection by Bacillus anthracis . Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition