Burkholderia pseudomallei
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| Burkholderia pseudomallei (Whitmore 1913) Yabuuchi et al. 1993 |
Burkholderia pseudomallei (previously Pseudomonas pseudomallei, Malleomyces pseudomallei, Pfeiferella pseudomallei, Bacillus whitmori) aka Whitmore's bacillus is a Gram-negative, bipolar, aerobic, motile rod-shaped bacterium.[1] A human and animal pathogen, B. pseudomallei causes melioidosis.
B. pseudomallei measures 2–5 μm in length and 0.4–0.8μm in diameter and are capable self-propulsion using flagellae. Endemic in soil and water of South-East Asia and North Australia, the two most important serovars clinically are (Type I/ara+ and Type II/ara-), corresponding to the above-mentioned geographic locations. Both serovars are roughly equal in pathogenicity and are distinguished by their ability to metabolize L-arabinose. The bacteria can grow in a number artficial nutrient environments, especially betaine- and arginine-containing.
In vitro, optimal proliferation temperature is reported around 40°C in pH-neutral or slightly acidic environments (pH 6.8–7.0). The majority of strains are capable of fermentation of sugars without gas formation (most importantly, glucose and galactose, older cultures are reported to also metabolize maltose and starch). Bacteria produce both exo- and endo-toxins. The role of the toxins identified in the process of melioidosis sympthom development has not been fully understood.[2]
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[edit] Identification
Laboratory identification of B. pseudomallei can be difficult, especially in Western countries where B. pseudomallei is rarely seen. The large wrinkled colonies look like environmental contaminants and are therefore often discarded as being of no clinical significance. Even when the culture is recognised to be significant, commonly used identification systems may misidentify the organism as Chromobacterium violaceum or other non-fermenting gram-negative bacilli.[3][4] Again, because of the rarity of the disease, identification of the bacterium B. pseudomallei in cultures may not actually trigger alarm bells in doctors unfamiliar with the disease.[5]
[edit] Disinfection
B. pseudomallei is susceptible to numerous disinfectants including benzalkonium chloride, iodine, mercuric chloride, potassium permanganate, 1% sodium hypochlorite, 70% ethanol, 2% glutaraldehyde and to a lesser extents, phenolic preparations. The microorganism can also be destroyed by heating to above 74°C for 10 min or by UV irradiation.
[edit] Treatment
Various antibiotics have been reported to be effective against B. pseudomallei—most notably, ceftazidime, tetracycline, doxycycline, gentamycin and bactrim. Laevomycetine-resistant strains have been recently reported.
Relative ease of cultivation combined with the significant symptoms associated with (Melioidosis) infections has raised interest to B. pseudomallei as well as to closely related B. mallei as a potential biological warfare agents.
[edit] Medical importance
B. pseudomallei is the cause of melioidosis. There are number of different forms of melioidosis, but sepsis due to B. pseudomallei has a mortality rate of 80 percent if untreated.
[edit] References
- ^ Burkholderia pseudomallei. VirginiaTech Pathogen Database. Retrieved on 2006-03-26.
- ^ Haase A, Janzen J, Barrett S, Currie B (1997). "Toxin production by Burkholderia pseudomallei strains and correlation with severity of melioidosis". J Med Microbiol 46 (7): 557-63. PMID 9236739.
- ^ Inglis TJ, Chiang D, Lee GS, Chor-Kiang L (1998). "Potential misidentification of Burkholderia pseudomallei by API 20NE". Pathology 30 (1): 62–4. PMID: 9534210.
- ^ Lowe P, Engler C, Norton R. (2002). "Comparison of automated and nonautomated systems for identification of Burkholderia pseudomallei". J Clin Microbiol 40 (12): 4625–27.
- ^ Kite-Powell A, Livengood JR, Suarez J, et al. (2006). "Imported Melioidosis—South Florida, 2005" 55 (32): 873–76.
[edit] External links
- Getting a Grip on the Great Mimicker: Secrets of a Stealth Organism from the Wellcome Trust.
