MELIOIDOSIS, CAUSED BY THE ENVIRONMENTAL GRAM-NEGATIVE BACILlus Burkholderia pseudomallei, is classically characterized by pneumonia and multiple abscesses, with a mortality rate of up to 40%. It is an important cause of community-acquired sepsis in Southeast Asia and northern Australia. Its known global distribution is expanding, a reflection of improvements in diagnostic microbiology and increasing numbers of cases in travelers and returning military personnel (Fig. 1). 1,2 A locally acquired case of melioidosis was recently described in the United States. 3 B. pseudomallei has been classified by the Centers for Disease Control and Prevention as a category B bioterrorism agent, resulting in increased research and understanding of melioidosis. This review considers recent developments in pathogenesis, diagnostics, and treatment.