You are rotating on the medical service and are asked to examine a patient who
was just admitted via the emergency department. He is acutely ill with a temperature
of 38.9 degrees centigrade, a respiratory rate of 22 breaths per minute, and a pulse
rate of 115 beats per minute. He is too ill to give a medical history and was admitted
unaccompanied.
Pertinent findings on physical examination include mental confusion, a positive
Kernig's sign, "flat" percussion notes with decreased tactile fremitus and distant
inspiratory crackles over both lung bases (left > right), and a localized erythematous
skin lesion (see below).
What is your diagnosis, what tests would you do to confirm your suspicions,
and what treatment, if any, do you recomment?
DIAGNOSIS: Pulmonary and cutaneous anthrax.
Anthrax is a highly contagious and potentially fatal zoonotic disease caused
by Bacillus anthracis - a Gram positive spore-forming rod. Herbivores are the natural hosts and humans usually
contract the disease by contact with an infected animal or animal product. However,
anthrax has the potential to be used as a weapon in bioterriorism.
Anthrax endospores are resistant to drying, heat, ultraviolet light, gamma radiation
and many disinfectants and can persist in dry soil for decades. Infection occurs when
the endospores enter the body through breaks in the skin (cutaneous anthrax), by inhalation
(pulmonary anthrax), and/or by ingestion (gastrointestinal anthrax). About 95% of
anthrax cases are cutaneous and 5% pulmonary. Gastrointestinal anthrax is rare, accounting
for <1% of cases. In the 20th century in the United States, 16 of the 18 reported
cases of pulmonary anthrax were fatal.
Uncomplicated cutaneous anthrax can be treated with penicillin-V 250 to 500
mg orally four times a day for 7-10 days. Pulmonary and gastrointestinal anthrax require
treatment with intravenous penicillin G 4 million units every 4-6 hours for at least
10 days. Addition of corticosteroids may be beneficial in inhalation anthrax. Immunization
is indicated for preventive therapy in persons at high risk of occupational exposure
and in those at risk of exposure via bioterrorism.
Cutaneous anthrax (left image) and inhalation anthrax with pneumonitis and hemorrhagic mediastinits (right image, arrows). The inhaled organism typically travels via lymphatics to involve the mediastinum. This patient also had sepsis and meningitis - the latter accounting for his positive Kernig's sign.
.