|B. pseudomallei colonies on Ashdown's agar showing the characteristic cornflower head morphology.|
Yabuuchi et al. 1993
Bacillus pseudomallei Whitmore 1913
Burkholderia pseudomallei (also known as Pseudomonas pseudomallei) is a aerobic, motile rod-shaped bacterium. It infects humans and animals and causes the disease melioidosis. It is also capable of infecting plants.
B. pseudomallei measures 2–5 μm in length and 0.4–0.8 μm in diameter and is capable of self-propulsion using flagellae. The bacteria can grow in a number of artificial nutrient environments, especially betaine- and arginine-containing ones.
In vitro, optimal proliferation temperature is reported around 40 °C in 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 endotoxins. The role of the toxins identified in the process of melioidosis symptom development has not been fully elucidated.
- Identification 1
- Disinfection 2
- Medical importance 3
- Antibiotic treatment and sensitivity testing 4
- Pathogenicity mechanisms and virulence factors 5
- Vaccine candidates 6
- References 7
- External links 8
B. pseudomallei is not fastidious and will grow on a large variety of culture media (colistin and gentamicin) and that again differentiates it from B. mallei, which is in contrast, exquisitely sensitive to a large number of antibiotics. For environmental specimens only, differentiation from the nonpathogenic B. thailandensis using an arabinose test is necessary (B. thailandensis is never isolated from clinical specimens). The laboratory identification of B. pseudomallei has been described in the literature.
The classic textbook description of B. pseudomallei in clinical samples is of an intracellular, bipolar-staining, Gram-negative rod, but this is of little value in identifying the organism from clinical samples. Some suggest the Wayson stain is useful for this purpose, but this has been shown not to be the case.
Laboratory identification of B. pseudomallei can be difficult, especially in Western countries where it is rarely seen. The large wrinkled colonies look like environmental contaminants, so are often discarded as being of no clinical significance. Colony morphology is very variable and a single strain may display up multiple colony types, so inexperienced laboratory staff may mistakenly believe the growth is not pure. The organism grows more slowly than other bacteria that may be present in clinical specimens, and in specimens from nonsterile sites, is easily overgrown. Nonsterile specimens should, therefore, be cultured in selective media (e.g., Ashdown's or B. cepacia medium). For heavily contaminated samples, such as faeces, a modified version of Ashdown's that includes norfloxacin, amoxicillin, and polymyxin B has been proposed. In blood culture, the BacT/ALERT MB system (normally used for culturing Mycobacterium) by bioMérieux has been shown to have superior yields compared to conventional blood culture media.
Even when the isolate is recognised to be significant, commonly used identification systems may misidentify the organism as API 20NE system accurately identifies B. pseudomallei in 99% of cases, as does the automated Vitek 1 system, but the automated Vitek 2 system only identifies 19% of isolates.
The pattern of resistance to antimicrobials is distinctive, and helps to differentiate the organism from P. aeruginosa. The majority of B. pseudomallei isolates are intrinsically resistant to all aminoglycosides (via an efflux pump mechanism), but sensitive to co-amoxiclav: this pattern of resistance almost never occurs in P. aeruginosa and is helpful in identification. Unfortunately, the majority of strains in Sarawak, Borneo, are susceptible to aminoglycosides and macrolides, which means the conventional recommendations for isolation and identification do not apply there.
Molecular methods (PCR) of diagnosis are possible, but not routinely available for clinical diagnosis. Fluorescence in situ hybridisation has also been described, but has not been clinically validated, and it is not commercially available. In Thailand, a latex agglutination assay is widely used, while a rapid immunofluorescence technique is also available in a small number of centres.
B. pseudomallei is susceptible to numerous disinfectants, including ultraviolet irradiation. B. pseudomallei is not reliably disinfected by chlorine.
B. pseudomallei infection in humans is called melioidosis. The mortality of melioidosis is 20 to 50% even with treatment.
Antibiotic treatment and sensitivity testing
The antibiotic of choice is ceftazidime. While various antibiotics are active in vitro (e.g., chloramphenicol, doxycycline, co-trimoxazole), they have been proven to be inferior in vivo for the treatment of acute melioidosis. Disc diffusion tests are unreliable when looking for co-trimoxazole resistance in B. pseudomallei (they greatly overestimate resistance) and Etests or agar dilution tests should be used in preference. The actions of co-trimoxazole and doxycycline are antagonistic, which suggests these two drugs ought not to be used together.
The organism is intrinsically resistant to
- genomes and related information"Burkholderia pseudomallei". PATRIC. NIAID.
- "Getting a Grip on the Great Mimicker: Secrets of a Stealth Organism". Wellcome Trust.
- Pathema Burkholderia resource
- "Burkholderia pseudomallei". NCBI Taxonomy Browser. 28450.
- Yabuuchi, E; Kosako, Y; Oyaizu, H; Yano, I; Hotta, H; Hashimoto, Y; Ezaki, T; Arakawa, M (1992). "Proposal of Burkholderia gen. nov. and transfer of seven species of the genus Pseudomonas homology group II to the new genus, with the type species Burkholderia cepacia (Palleroni and Holmes 1981) comb. nov.". Microbiol Immunol 36 (12): 1251–75.
- "Burkholderia pseudomallei". VirginiaTech Pathogen Database. Retrieved 2006-03-26.
- Lee YH, Chen Y, Ouyang X, Gan YH (2010). "Burkholderia pseudomallei"Identification of tomato plant as a novel host model for . BMC Microbiol 10: 28.
- Haase A, Janzen J, Barrett S, Currie B (July 1997). "Toxin production by Burkholderia pseudomallei strains and correlation with severity of melioidosis". Journal of Medical Microbiology 46 (7): 557–63.
- Peacock SJ, Chieng G, Cheng AC; et al. (October 2005). "Burkholderia pseudomallei selective agar for clinical isolation of Burkholderia pseudomallei medium, and Burkholderia cepacia"Comparison of Ashdown's medium, . Journal of clinical microbiology 43 (10): 5359–61.
- Chaiyaroj SC, Kotrnon K, Koonpaew S, Anantagool N, White NJ, Sirisinha S (1999). "Differences in genomic macrorestriction patterns of arabinose-positive (Burkholderia thailandensis) and arabinose-negative Burkholderia pseudomallei". Microbiology and immunology 43 (7): 625–30.
- Walsh AL, Wuthiekanun V (1996). "The laboratory diagnosis of melioidosis.". Br J Biomed Sci 53 (4): 249–53.
- Brundage WG, Thuss CJ, Walden DC (March 1968). "Four fatal cases of melioidosis in U. S. soldiers in Vietnam. Bacteriologic and pathologic characteristics". The American journal of tropical medicine and hygiene 17 (2): 183–91.
- Sheridan EA, Ramsay AR, Short JM, Stepniewska K, Wuthiekanun V, Simpson AJ (May 2007). "Evaluation of the Wayson stain for the rapid diagnosis of melioidosis". Journal of clinical microbiology 45 (5): 1669–70.
- Chantratita N, Wuthiekanun V, Boonbumrung K; et al. (2007). "Burkholderia pseudomallei."Biological relevance of colony morphology and phenotypic switching by . J Bacteriol 189 (3): 807–17.
- Pumpuang A, Chantratita N, Wikraiphat C; et al. (2011). in distilled water for 16 years"Burkholderia pseudomallei"Survival of . Trans R Soc Trop Med Hyg 105 (10–2): 598–600.
- Ashdown LR (1979). "An improved screening technique for isolation of Pseudomonas pseudomallei from clinical specimens". Pathology 11 (2): 293–7.
- Roesnita B, Tay ST, Puthucheary SD, Sam IC. (2012). "Diagnostic use of Burkholderia pseudomallei selective media in a low prevalence setting.". Trans R Soc Trop Med Hyg 106 (2): 131–3.
- Goodyear A, Strange L, Rholl DA; et al. (2013). from contaminated specimens."Burkholderia pseudomallei"An improved selective culture medium enhances the isolation of . Am J Trop Med Hyg 89 (5): 973–82.
- Jorakate P, Higdon M, Kaewpan A; et al. (2015). "Contribution of the BacT/ALERT MB Mycobacteria Bottle to bloodstream infection surveillance in Thailand: added yield for Burkholderia pseudomallei.". J Clin Microbiol 53 (3): 910–4.
- Inglis TJ, Chiang D, Lee GS, Chor-Kiang L (February 1998). "Potential misidentification of Burkholderia pseudomallei by API 20NE". Pathology 30 (1): 62–4.
- Lowe P, Engler C, Norton R (December 2002). "Burkholderia pseudomallei"Comparison of automated and nonautomated systems for identification of . Journal of clinical microbiology 40 (12): 4625–7.
- Kite-Powell A, Livengood JR, Suarez J; et al. (2006). "Imported Melioidosis—South Florida, 2005". Morb Mortal Wkly Rep 55 (32): 873–6.
- Amornchai P, Chierakul W, Wuthiekanun V; et al. (November 2007). identification using the API 20NE system and a latex agglutination test"Burkholderia pseudomallei"Accuracy of . Journal of clinical microbiology 45 (11): 3774–6.
- Moore RA, DeShazer D, Reckseidler S, Weissman A, Woods DE (March 1999). "Burkholderia pseudomallei"Efflux-mediated aminoglycoside and macrolide resistance in . Antimicrobial agents and chemotherapy 43 (3): 465–70.
- Wuthiekanun V, Peacock SJ (June 2006). "Management of melioidosis". Expert review of anti-infective therapy 4 (3): 445–55.
- Hodgson K, Engler C, Govan B; et al. (2009). "Burkholderia pseudomallei"A comparison of routine bench and molecular diagnostic methods in the identification of . J Clin Microbiol 47 (5): 1578–80.
- Podin Y, Sarovich DS, Price EP, Kaestli M, Mayo M, Hii K; et al. (2013). "Burkholderia pseudomallei from Sarawak, Malaysian Borneo are predominantly susceptible to aminoglycosides and macrolides". Antimicrob Agents Chemother 58 (1): 162–6.
- Ruppitsch W, Stöger A, Indra A; et al. (March 2007). "Suitability of partial 16S ribosomal RNA gene sequence analysis for the identification of dangerous bacterial pathogens". Journal of applied microbiology 102 (3): 852–9.
- Wattiau P, Van Hessche M, Neubauer H, Zachariah R, Wernery U, Imberechts H (March 2007). and related bacteria by multiple-locus sequence typing-derived PCR and real-time PCR"Burkholderia pseudomallei"Identification of . Journal of clinical microbiology 45 (3): 1045–8.
- Hagen RM, Frickmann H, Elschner M; et al. (2011). "Rapid identification of Burkholderia pseudomallei and Burkholderia mallei by fluorescence in situ hybridization (FISH) from culture and paraffin-embedded tissue samples". Int J Med Microbiol 301 (7): 585–90.
- Wuthiekanun V, Desakorn V, Wongsuvan G; et al. (April 2005). "Rapid immunofluorescence microscopy for diagnosis of melioidosis". Clinical and diagnostic laboratory immunology 12 (4): 555–6.
- Miller, WR; Pannell, L; Cravitz, L; Tanner, WA; Ingalls, MS (1948). I. Morphology, cultivation, viability, and isolation from contaminated specimens"Malleomyces pseudomallei: and Malleomyces mallei"Studies on certain biological characteristics of . J Bacteriol 55 (1): 115–126.
- Wuthiekanun V, Wongsuwan G, Pangmee S, Teerawattanasook N, Day NP, Peacock SJ (2010). a select agent and the cause of melioidosis"Burkholderia pseudomallei,"Perasafe, Virkon and bleach are bactericidal for . J Hosp Infect 77 (2): 183–4.
- Howard K, Inglis TJJ (2003). in potable water"Burkholderia pseudomallei"The effect of free chlorine on . Water Res 37 (18): 4425–32.
- Howard K, Inglis TJJ (2005). "Disinfection of Burkholderia pseudomallei in potable water". Water Res 39 (6): 1085–92.
- White NJ, Dance DA, Chaowagul W, Wattanagoon Y, Wuthiekanun V, Pitakwatchara N (September 1989). "Halving of mortality of severe melioidosis by ceftazidime". Lancet 2 (8665): 697–701.
- Lumbiganon P, Tattawasatra U, Chetchotisakd P; et al. (2000). "Comparison between the antimicrobial susceptibility of Burkholderia pseudomallei to trimethoprim-sulfamethoxazole by standard disk diffusion method and by minimal inhibitory concentration determination". J Med Assoc Thai 83 (8): 856–60.
- Wuthiekanun V, Cheng AC, Chierakul W; et al. (2005). "Trimethoprim/sulfamethoxazole resistance in clinical isolates of Burkholderia pseudomallei". J Antimicrob Chemother 55 (6): 1029–31.
- Saraya S, Soontornpas C, Chindavijak B, Mootsikapun P (2009). "In vitro interactions between cotrimoxazole and doxycycline in Burkholderia pseudomallei: how important is this combination in maintenance therapy of melioidosis?". Indian J Med Microbiol 27 (1): 88–9.
- Trunck LA; Propst, KL; Wuthiekanun, V; Tuanyok, A; Beckstrom-Sternberg, SM; Beckstrom-Sternberg, JS; Peacock, SJ; Keim, P; et al. (2009). Picardeau, Mathieu, ed. clinical isolates from Thailand"Burkholderia pseudomallei"Molecular basis of rare aminoglycoside susceptibility and pathogenesis of . PLoS Negl Trop Dis 3 (9): e519.
- Ashdown, LR (1979). in the clinical laboratory"Pseudomonas pseudomallei"Identification of . J Clin Pathol 32 (5): 500–4.
- Kespichayawattana W, Intachote P, Utaisincharoen P, Stitaya Sirisinha S (2004). "Virulent Burkholderia pseudomallei is more efficient than avirulent Burkholderia thailandensis in invasion of and adherence to cultured human epithelial cells". Microbial Pathogenesis 36 (5): 287–9.
- Nandi T, Ong C, Singh AP, Boddey J, Atkins T, Sarkar-Tyson M, Essex-Lopresti AE, Chua HH, Pearson T, Kreisberg JF, Nilsson C, Ariyaratne P, Ronning C, Losada L, Ruan Y, Sung WK, Woods D, Titball RW, Beacham I, Peak I, Keim P, Nierman WC, Tan P (2010). Guttman, David S., ed. provides insights into the evolution of accidental virulence"Burkholderia pseudomallei"A genomic survey of positive selection in . PLoS Pathog. 6 (4): e1000845.
- Sim SH, Yu Y, Lin CH; et al. (October 2008). Achtman, Mark, ed. : implications for human melioidosis"Burkholderia pseudomallei"The core and accessory genomes of . PLoS Pathog. 4 (10): e1000178.
- Price EP, Hornstra HM, Limmathurotsakul D; et al. (2010). Guttman, David S., ed. in four cases of acute melioidosis"Burkholderia pseudomallei"Within-host evolution of . PLoS Pathog. 6 (1): e1000725.
- Wiersinga WJ, van der Poll T, White NJ, Day NP, Peacock SJ (2006). "Melioidosis: insights into the pathogenicity of Burkholderia pseudomallei.". Nature Reviews Microbiology 4 (4): 272–82.
- Kespichayawattana W, Rattanachetkul S, Wanun T; et al. (2000). induces cell fusion and actin-associated membrane protrusion: a possible mechanism for cell-to-cell spreading"Burkholderia pseudomallei". Infect. Immun. 68 (9): 5377–84.
- Cruz-Migoni A, Hautbergue GM, Artymiuk PJ; et al. (2011). ."eIF4A toxin inhibits helicase activity of translation factor Burkholderia pseudomallei"A . Science 334 (6057): 821–4.
- Shalom G, Shaw JG, Thomas MS (August 2007). that is induced upon invasion of macrophages"Burkholderia pseudomallei"In vivo expression technology identifies a type VI secretion system locus in . Microbiology 153 (Pt 8): 2689–99.
- Mima T, Schweizer HP (2010). 1026b does not play a role in quorum sensing, virulence factor production, or extrusion of aminoglycosides, but is a broad-spectrum drug efflux system"Burkholderia pseudomallei"The BpeAB-OprB efflux pump of . Antimicrob. Agents Chemother. 54 (8): 3113–20.
- Norris MH, Kang Y, Lu D, Wilcox BA, Hoang TT (2009). "Burkholderia pseudomallei. of dapB and asd"Glyphosate resistance as a novel select-agent-compliant, non-antibiotic-selectable marker in chromosomal mutagenesis of the essential genes . Appl Environ Microbiol 75 (19): 6062–75.
- Norris MH, Propst KL, Kang Y; et al. (2011). Δasd mutant exhibits attenuated intracellular infectivity and imparts protection against acute inhalation melioidosis in mice"Burkholderia pseudomallei"The . Infect Immun 79 (10): 4010–8.
No vaccine is currently available, but a number of vaccine candidates have been suggested. Aspartate-β-semialdehyde dehydrogenase (asd) gene deletion mutants are auxotrophic for diaminopimelate (DAP) in rich media and auxotrophic for DAP, lysine, methionine, and threonine in minimal media. The Δasd bacterium (bacterium with the asd gene removed) protects against inhalational melioidosis in mice.
B. pseudomallei is intrinsically resistant to a large number of antimicrobial agents. One important mechanism is that it is able to pump drugs out of the cell, and this mediates resistance to aminoglycosides (AmrAB-OprA), tetracyclines, fluoroquinolones, and macrolides (BpeAB-OprB).
 It is able to polymerise  is able to invade cells (it is an intracellular pathogen).B. pseudomallei
 Strains which cause disease in humans differ from those causing disease in other animals by possessing certain
B. pseudomallei is an "accidental pathogen". An environmental organism, it has no requirement to pass through an animal host to replicate. From the point of view of the bacterium, human infection is an evolutionary "dead end".
Pathogenicity mechanisms and virulence factors
 in the laboratory, but the concentrations used are much higher than those achievable in humans.B. pseudomallei is used to kill Kanamycin