Burkholderia pseudomallei
Summary
Burkholderia pseudomallei is a gram-negative soil and water saprophyte of Southeast Asia and northern Australia that causes melioidosis. It produces abscesses in lung, liver, spleen, and skin, and can reactivate years after exposure, earning the name 'the great mimicker' and 'Vietnamese time bomb'.
Detail
Infection follows percutaneous inoculation through skin breaks, inhalation, or ingestion during the rainy season, particularly in rice farmers. It is a facultative intracellular organism, which underlies its capacity for latency and relapse. Diabetes mellitus is the dominant risk factor, along with chronic kidney disease, alcohol use, and thalassaemia. Presentations range from localized skin ulcer or abscess to fulminant pneumonia resembling tuberculosis with upper lobe cavitation, to septicaemia with multiple visceral abscesses; splenic and prostatic abscesses are characteristic. On culture the organism has a wrinkled colony morphology and a bipolar 'safety pin' appearance on staining. Treatment is prolonged and biphasic: an intensive phase of intravenous ceftazidime or a carbapenem for at least two weeks, then an eradication phase of oral trimethoprim-sulfamethoxazole for three to six months to prevent relapse. It is a category B bioterrorism agent and a laboratory hazard. B. cepacia is the related organism that colonizes patients with cystic fibrosis and predicts rapid decline.
Sources
- Harrison's Principles of Internal Medicine
- Levinson Medical Microbiology and Immunology
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