American Board of Internal Medicine (ABIM) Certification Practice Exam

What type of clinical presentation is associated with Bacillus anthracis?

1. Purulent drainage and necrosis

2. Edematous pruritic lesion with central eschar

3. Fever and malaise without lesions

4. Corynebacterial ulcerations

The correct answer is: Edematous pruritic lesion with central eschar

Bacillus anthracis, the causative agent of anthrax, is known for causing specific clinical presentations, particularly the cutaneous form of the disease. This form is characterized by an edematous pruritic lesion that develops into a central eschar, which is a dry, dark scab or dead tissue that typically forms after an ulceration occurs. The initial papule becomes vesicular and then progresses to a characteristic black necrotic ulcer, which is surrounded by substantial edema. The presence of the eschar along with the preceding pruritic lesion is a distinctive feature of cutaneous anthrax and helps in differentiating it from other infections and conditions. This presentation typically follows exposure to infected animals or contaminated animal products, making it a significant concern in certain geographical and occupational settings. The other clinical presentations mentioned would not align with the typical characteristics of Bacillus anthracis infections. For example, purulent drainage and necrosis would suggest a different type of bacterial infection, often involving pyogenic bacteria, while fever and malaise without lesions may occur in systemic or generalized infections but lack the distinct localized manifestation seen in cutaneous anthrax. Corynebacterial ulcerations would be related to infections caused by other bacteria, such as Corynebacter