Bacterial Agents Used for Bioterrorism

Jan K. Horn

In This Article

Melioidosis and Glanders

Melioidosis is caused by a gram-negative bacillus, Burkholderia psuedomallei, which normally inhabits stagnant ponds and rice paddies.[14,15] The organism is strictly limited between 20° N and 20° S latitude and accounts for 40% of infectious deaths in Thailand. Only 343 U.S. cases have been reported; however, 36 cases in Vietnam led to mortality. Disease is contracted through skin abrasions or by inhalation of aerosols. Localized suppurative infection often leads to abscess, lymphangitis, and regional adenopathy. A chronic suppurative form of the disease leads to pulmonary infection that mimics tuberculosis. Acute pulmonary infection is more serious with rapidly progressive cavitary pneumonia. Any of these clinical forms can evolve with bacteremia. Such diffuse bacteremia is then often associated with metastatic infection and a diffuse pustular rash.

Glanders is a disease caused by Burkholderia mallei, which ordinarily infects equidae.[16,17] Pigs and cattle appear to be absolutely resistant. The organism rarely infects humans; the last reported U.S. case was in 1938. Risk factors are contact with equidae or laboratory exposure. The clinical presentation and manifestations are similar to those described above for melioidosis. Acute infections with systemic manifestations, pneumonia, and bacteremia are distinguished from a chronic indolent form of infection associated with subcutaneous ulcers, lymphatic thickening, and generation of lymphatic nodules.

There is a paucity of in vivo data on treatment of humans. Postexposure prophylaxis is usually accomplished with empiric therapy consisting of TMP/SMX, ceftazidime, and gentamycin, given parenterally for two weeks followed by oral therapy for six months. Surgical drainage of abscesses may be required and treatment of localized disease may only require therapy for two to five months with amoxicillin, tetracycline, or TMP/SMX.

Presented at the 22nd Annual Meeting of the Surgical Infection Society, Madrid, May 2–4, 2002.


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