Burkholderia pseudomallei and Burkholderia mallei: Melioidosis and glanders

The genus Burkholderia is currently composed of many species, but only three are notable pathogens for humans or animals: the former cepacia complex (described in Chapter 220) pseudomallei (the agent of melioidosis), and mallei (the agent of equine glanders). All three are aerobic, nonsporulating, straight or slightly curved gram-negative bacilli that were formerly placed in the genus Pseudomonas. Melioidosis Melioidosis is a disease of humans and animals; it has enormous clini-cal diversity, spanning asymptomatic infection, localized skin ulcers or abscesses, chronic pneumonia mimicking tuberculosis, and fulminant septic shock with abscesses in multiple internal organs. Most disease is from recent infection, but latency with reactivation is described up to 62 years after exposure. Most cases are reported from Southeast Asia and northern Australia, but melioidosis is increasingly being recog-nized in people infected in an endemic region who return or travel to Europe and the United States. The causative bacterium, Burkholderia pseudomallei, is also considered a potential biologic warfare agent.