Burkholderia pseudomallei: Wikis

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Burkholderia pseudomallei
B. pseudomallei colonies on Ashdown's agar showing the characteristic cornflower head morphology.
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Beta Proteobacteria
Order: Burkholderiales
Family: Burkholderiaceae
Genus: Burkholderia
Species: B. pseudomallei
Binomial name
Burkholderia pseudomallei
(Whitmore 1913)
Yabuuchi et al. 1993[1]
Synonyms

Bacillus pseudomallei Whitmore 1913
Bacterium whitmori Stanton and Fletcher 1921
Malleomyces pseudomallei Breed 1939
Loefflerella pseudomallei Brindle and Cowan 1951
Pfeiferella pseudomallei
Pseudomonas pseudomallei (Whitmore 1913) Haynes 1957

Burkholderia pseudomallei is a Gram-negative, bipolar, aerobic, motile rod-shaped bacterium.[2] A human and animal pathogen, B. pseudomallei causes melioidosis.

B. pseudomallei measures 2–5 μm in length and 0.4–0.8 μm in diameter and are capable of self-propulsion using flagellae. 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 symptom development has not been fully understood.[3]

Contents

Identification

B. pseudomallei grows on a large variety of culture media (blood agar, MacConkey agar, EMB, etc.). Ashdown's medium (or Burkholderia cepacia medium) may be used for selective isolation.[4] Cultures typically become positive in 24 to 48 hours (this rapid growth rate differentiates the organism from B. mallei, which typically takes a minimum of 72 hours to grow), and colonies are wrinkled, have a metallic appearance, and possess an earthy odour. On Gram staining, the organism is a Gram-negative rod with a characteristic "safety pin" appearance (bipolar staining). On sensitivity testing, the organism appears highly resistant (it is innately resistant to a large number of antibiotics including 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 non-pathogenic B. thailandensis using an arabinose test is necessary (B. thailandensis is never isolated from clinical specimens).[5]

The classic textbook description of B. pseudomallei in clinical samples is of a intracellular bipolar-staining Gram-negative rod, but this is of little value in identifying the organism from clinical samples.[6] It has been suggested by some[7] that the Wayson stain is useful for this purpose, but this has been shown not to be the case.[8]

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. The organism grows more slowly than other bacteria that may be present in clinical specimens, and in specimens from non-sterile sites, is easily overgrown. Non-sterile specimens should therefore be cultured in selective media (e.g., Ashdown's[9] or B. cepacia medium.[4] Even when the isolate is recognised to be significant, commonly used identification systems may misidentify the organism as Chromobacterium violaceum or other non-fermenting gram-negative bacilli such as Burkholderia cepacia or Pseudomonas aeruginosa.[10][11] Again, because the disease is rarely seen in western countries, identification of the bacterium B. pseudomallei in cultures may not actually trigger alarm bells in physicians unfamiliar with the disease.[12] Routine biochemical methods for identification of bacteria vary widely in their identification of this organism: the API 20NE system accurately identifies B. pseudomallei in 99% of cases,[13] as does the automated Vitek 1 system, but the automated Vitek 2 system only identifies 19% of isolates.[11]

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),[14] but sensitive to co-amoxiclav:[15] this pattern of resistance never occurs in P. aeruginosa and is helpful in identification.[16]

Molecular methods (PCR) of diagnosis are possible, but not routinely available for clinical diagnosis.[17][18]

In Thailand, a latex agglutination assay is widely used.[13] A rapid immunofluorescence technique is also available in a small number of centres in Thailand.[19]

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 extent, phenolic preparations.[20] The microorganism can also be destroyed by heating to above 74°C for 10 min or by UV irradiation. B. pseudomallei is not reliably disinfected by chlorine.[21][22]

Treatment

The antibiotic of choice is ceftazidime.[15] 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.[23]

The organism is intrinsically resistant to gentamicin[24] and to colistin, and this fact is helpful in the identification of the organism.[25]

Medical importance

B. pseudomallei infection in humans is called melioidosis. The mortality of melioidosis is 20 to 50% even with treatment.

Pathogenicity mechanisms

Strains which cause disease in humans differ from those causing disease in other animals by possessing certain genomic islands.[26]

B. pseudomallei is one of the first proteobacteria to be identified as containing an active Type 6 secretion system. it is also the single organism identified that probably contains up to 6 different independent type 6 secretion system.[27]

It may have the ability to cause disease in humans because of DNA it has acquired from other microorganisms.[26]

References

  1. ^ 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): 1251–1275. PMID 1283774.  
  2. ^ "Burkholderia pseudomallei". VirginiaTech Pathogen Database. http://pathport.vbi.vt.edu/pathinfo/pathogens/Burkholderia_pseudomallei.html. Retrieved 2006-03-26.  
  3. ^ 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. doi:10.1099/00222615-46-7-557. PMID 9236739.  
  4. ^ a b Peacock SJ, Chieng G, Cheng AC, et al. (October 2005). "Comparison of Ashdown's medium, Burkholderia cepacia medium, and Burkholderia pseudomallei selective agar for clinical isolation of Burkholderia pseudomallei". Journal of clinical microbiology 43 (10): 5359–61. doi:10.1128/JCM.43.10.5359-5361.2005. PMID 16208018. PMC 1248505. http://jcm.asm.org/cgi/pmidlookup?view=long&pmid=16208018.  
  5. ^ 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. PMID 10529102.  
  6. ^ Walsh AL, Wuthiekanun V (December 1996). "The laboratory diagnosis of melioidosis". British journal of biomedical science 53 (4): 249–53. PMID 9069100.  
  7. ^ 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. PMID 4869109. http://www.ajtmh.org/cgi/pmidlookup?view=long&pmid=4869109.  
  8. ^ 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. doi:10.1128/JCM.00396-07. PMID 17360835. PMC 1865910. http://jcm.asm.org/cgi/pmidlookup?view=long&pmid=17360835.  
  9. ^ Ashdown LR (1979). "An improved screening technique for isolation of Pseudomonas pseudomallei from clinical specimens". Pathology 11 (2): 293–7. doi:10.3109/00313027909061954. PMID 460953.  
  10. ^ Inglis TJ, Chiang D, Lee GS, Chor-Kiang L (February 1998). "Potential misidentification of Burkholderia pseudomallei by API 20NE". Pathology 30 (1): 62–4. doi:10.1080/00313029800169685. PMID 9534210.  
  11. ^ a b Lowe P, Engler C, Norton R (December 2002). "Comparison of automated and nonautomated systems for identification of Burkholderia pseudomallei". Journal of clinical microbiology 40 (12): 4625–7. doi:10.1128/JCM.40.12.4625-4627.2002. PMID 12454163. PMC 154629. http://jcm.asm.org/cgi/pmidlookup?view=long&pmid=12454163.  
  12. ^ Kite-Powell A, Livengood JR, Suarez J, et al. (2006). "Imported Melioidosis—South Florida, 2005". Morb Mortal Wkly Rep 55 (32): 873–76. PMID 16915220. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5532a1.htm.  
  13. ^ a b Amornchai P, Chierakul W, Wuthiekanun V, et al. (November 2007). "Accuracy of Burkholderia pseudomallei identification using the API 20NE system and a latex agglutination test". Journal of clinical microbiology 45 (11): 3774–6. doi:10.1128/JCM.00935-07. PMID 17804660. PMC 2168515. http://jcm.asm.org/cgi/pmidlookup?view=long&pmid=17804660.  
  14. ^ Moore RA, DeShazer D, Reckseidler S, Weissman A, Woods DE (March 1999). "Efflux-mediated aminoglycoside and macrolide resistance in Burkholderia pseudomallei". Antimicrobial agents and chemotherapy 43 (3): 465–70. PMID 10049252. PMC 89145. http://aac.asm.org/cgi/pmidlookup?view=long&pmid=10049252.  
  15. ^ a b Wuthiekanun V, Peacock SJ (June 2006). "Management of melioidosis". Expert review of anti-infective therapy 4 (3): 445–55. doi:10.1586/14787210.4.3.445. PMID 16771621. http://www.future-drugs.com/doi/abs/10.1586/14787210.4.3.445?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dncbi.nlm.nih.gov.  
  16. ^ Hodgson K, Engler C, Govan B, et al. (2009). "A comparison of routine bench and molecular diagnostic methods in the identification of Burkholderia pseudomallei". J Clin Microbiol 47 (5): 1578–80. doi:10.1128/JCM.02507-08. PMID 19279182.  
  17. ^ 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. doi:10.1111/j.1365-2672.2006.03107.x. PMID 17309636. http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1364-5072&date=2007&volume=102&issue=3&spage=852.  
  18. ^ Wattiau P, Van Hessche M, Neubauer H, Zachariah R, Wernery U, Imberechts H (March 2007). "Identification of Burkholderia pseudomallei and related bacteria by multiple-locus sequence typing-derived PCR and real-time PCR". Journal of clinical microbiology 45 (3): 1045–8. doi:10.1128/JCM.02350-06. PMID 17251403. PMC 1829090. http://jcm.asm.org/cgi/pmidlookup?view=long&pmid=17251403.  
  19. ^ 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. doi:10.1128/CDLI.12.4.555-556.2005. PMID 15817767. PMC 1074392. http://cvi.asm.org/cgi/pmidlookup?view=long&pmid=15817767.  
  20. ^ Miller, WR; Pannell, L; Cravitz, L; Tanner, WA; Ingalls, MS (1948). "Studies on certain biological characteristics of Malleomyces mallei and Malleomyces pseudomallei: I. Morphology, cultivation, viability, and isolation from contaminated specimens". J Bacteriol 55 (1): 115–126. PMID 16561426.  
  21. ^ Howard K, Inglis TJJ|title=The effect of free chlorine on Burkholderia pseudomallei in potable water|journal=Water Res|volume=37|issue=18|pages=4425–4432|year=2003|doi=10.1016/S0043-1354(03)00440-8}}
  22. ^ Howard K, Inglis TJJ (2005). "Disinfection of Burkholderia pseudomallei in potable water". Water Res 39 (6): 1085–1092. doi:10.1016/j.watres.2004.12.028.  
  23. ^ 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. doi:10.1016/S0140-6736(89)90768-X. PMID 2570956. http://linkinghub.elsevier.com/retrieve/pii/S0140-6736(89)90768-X.  
  24. ^ Trunck LA; Propst, KL; Wuthiekanun, V; Tuanyok, A; Beckstrom-Sternberg, SM; Beckstrom-Sternberg, JS; Peacock, SJ; Keim, P et al. (2009). "Molecular basis of rare aminoglycoside susceptibility and pathogenesis of Burkholderia pseudomallei clinical isolates from Thailand". PLoS Negl Trop Dis 3 (9): e519. doi:10.1371/journal.pntd.0000519. PMID 19771149.  
  25. ^ Ashdown, LR (1979). "Identification of Pseudomonas pseudomallei in the clinical laboratory". J Clin Pathol 32 (5): 500–04. doi:10.1136/jcp.32.5.500. PMID 381328.  
  26. ^ a b Sim SH, Yu Y, Lin CH, et al. (October 2008). "The core and accessory genomes of Burkholderia pseudomallei: implications for human melioidosis". PLoS pathogens 4 (10): e1000178. doi:10.1371/journal.ppat.1000178. PMID 18927621. PMC 2564834. http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1000178.  
  27. ^ Shalom G, Shaw JG, Thomas MS (August 2007). "In vivo expression technology identifies a type VI secretion system locus in Burkholderia pseudomallei that is induced upon invasion of macrophages". Microbiology 153 (Pt 8): 2689–99. doi:10.1099/mic.0.2007/006585-0. PMID 17660433. http://mic.sgmjournals.org/cgi/pmidlookup?view=long&pmid=17660433.  

External links

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Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Superregnum: Bacteria
Regnum: Bacteria
Phylum: Proteobacteria
Classis: Beta Proteobacteria
Ordo: Burkholderiales
Familia: Burkholderiaceae
Genus: Burkholderia
Group: pseudomallei group
Spieces: Burkholderia pseudomallei
Strain: Burkholderia pseudomallei 1106a - Burkholderia pseudomallei 1710b - Burkholderia pseudomallei 668 - Burkholderia pseudomallei K96243


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