Review Question - QID 221320

Anthrax Treatment Medical QID: 221320 (M2.OMB.4673)

QID 221320 (Type "221320" in App Search)

A 42-year-old man presents to the emergency department with a 3-day history of a rash on his arm. He suffered a number of scrapes while clearing thorn bushes about 1 week ago on his farm. A few days later, he began to notice an itchy, raised lesion near the site of the cuts that filled with liquid. About 1 day later, the lesion popped and began to turn black. He has no significant medical history and drinks 10-15 alcoholic beverages per week, and does not smoke. His temperature is 99.0°F (37.2°C), blood pressure is 135/75 mmHg, pulse is 78/min, respirations are 14/min, and O2 saturation is 99%. The lesion is shown in Figure A. He is diagnosed and treated appropriately. Five days later, the patient returns to clinic complaining of a painful rash on his face and forearms bilaterally after going back out to work on the farm. Which of the following is the most likely cause of this patient's new symptoms?

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Consequence of bacterial death

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Inadequate treatment

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Noncompliance with treatment

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Progression of disease

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Side effect of medication

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This rancher who presents with a pruritic papule that progressed into a black eschar most likely has cutaneous anthrax, which is typically treated with doxycycline. A common side effect of doxycycline is photosensitivity.

Cutaneous anthrax is caused by contact with infected animals through an open cut or wound in the skin. The pathophysiology underlying this disease is the production of edema toxin by Bacillus anthracis. This toxin increases cyclic adenylyl monophosphate production and results in vasodilation and necrosis of local soft tissue. Patients will present with a painless pruritic papule that progresses to a vesical or bullae. Eventually, this lesion will undermine and turn into a painless black eschar with surrounding edema. The mainstay of treatment for this disease is ciprofloxacin. Doxycycline can also be used for limited disease. A side effect of doxycycline is photosensitivity.

Manzuli et al. review the antibiotic susceptibility of anthrax strains. They discuss how over 15 different antibiotics have been tested in vitro against anthrax. They recommend ciprofloxacin, doxycycline, penicillin G, and amoxicillin for treatment.

Figure/Illustration A is a clinical photograph showing a black eschar with surrounding edema (black circle). This presentation is classically seen in patients with cutaneous anthrax.

Incorrect Answers:
Answer 1: Bacterial death can cause side effects in patients with spirochete infections such as syphilis. This Jarisch-Herxheimer reaction is caused by the acute release of bacterial antigens into the bloodstream and results in headache, fever, muscle aches, and skin rashes. This is expected in the treatment of syphilis and is not an indication to discontinue treatment.

Answer 2: Inadequate treatment of cutaneous anthrax is incorrect because this would not lead to the development of a photosensitive rash. Rather, this new pattern of rash results from the side effect of treatments such as ciprofloxacin and doxycycline.

Answer 3: Noncompliance with treatment can result in the development of bacterial resistance to antibiotics but would not result in photosensitivity. Compliance is especially important in bacteria that are able to mutate quickly such as Mycobacterium tuberculosis.

Answer 4: Progression of the disease is unlikely because cutaneous anthrax rarely disseminates to systemic anthrax and would be unlikely to do so in the presence of appropriate antibiotic treatment. Pulmonary anthrax is caused instead by the inhalation of spores. It is associated with pulmonary hemorrhage, mediastinitis, and death.

Bullet Summary:
Cutaneous anthrax presents with a painless black eschar and can be treated with doxycycline, which may cause photosensitivity.