Burkholderia pseudomallei |
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Burkholderia pseudomallei is a Gram-negative, motile, non-spore-forming, saprophytic aerobe found in contaminated water, soil, and on market produce. It is the causative agent of melioidosis, an infectious disease endemic to southeast Asia and northern Australia, and may occur in other tropical and subtropical regions. Transmission to humans and animals occurs through direct contact with the organism in the environment via ingestion, inhalation, or through open wounds and skin abrasions. The role of insect bites is uncertain, and direct human-to-human and animal-to-human transmission is rare but can occur after contact with blood or body fluids. Depending on the site of the infection, contaminated body fluids may include urine, nasal secretions and milk. Infections may remain latent for years, and the incubation period of infection can vary from two days, to many years.
Manifestation of melioidosis can be categorized as acute localized skin infection or septicaemia, acute pulmonary infection, and chronic suppurative infection. Chronic suppurative infections often develop with secondary abscesses in the skin, brain, lungs, myocardium, liver, spleen, bones, lymph nodes, or eyes. Melioidosis requires prolonged treatment with antibiotics. Isolates are generally susceptible to imipenem, piperacillin, amoxycillin-clavulanic acid, doxycycline, ceftazidime, aztreonam and chloramphenicol, and have been found to be is resistant to colistin and gentamicin. There is currently no effective vaccine against this disease. Outside the host, Burkholderia pseudomallei can survive for months in limited nutrients and acidic environments. The production of specialized secondary metabolites and adaptation of complex catabolic pathways and transport systems contribute to this organism’s capacity for survival in diverse, competitive environments. B. pseudomallei is a facultative intracellular pathogen, but the underlying mechanism of intracellular survival is not fully understood. Known virulence determinates include the flagella and a type II protein secretion system, with potential virulence factors including surface polysaccharides, exoproteins, fimbriae, pilli, and putative adhesions [1]. The severe course of infection, aerosol infectivity and worldwide availability of this pathogen has resulted in its inclusion as a potential agent of biological warfare or bioterrorism, and is listed on the Centers for Disease Control list as a Category B bioterrorism agent. Systematic name (1997): Burkholderia pseudomallei Lineage: Bacteria; Proteobacteria; Betaproteobacteria; Burkholderiales; Burkholderiaceae; Burkholderia; pseudomallei group; Burkholderia pseudomallei Older names:
[1] Genomic plasticity of the causative agent of melioidosis, Burkholderia pseudomallei. Proc Natl Acad Sci U S A. 2004 Sep 28;101(39):14240-5. Epub 2004 Sep 17. Other web resources: The Center for Disease Control Tropical Medicine Central Resource Material Safety Data Sheet - Infectious Substances |
