title: Landscape changes influence the occurrence of the melioidosis bacterium Burkholderia pseudomallei in soil in northern Australia.
abstract: BACKGROUND
  The soil-dwelling saprophyte bacterium Burkholderia pseudomallei is the cause of melioidosis, a severe disease of humans and animals in southeast Asia and northern Australia. Despite the detection of B. pseudomallei in various soil and water samples from endemic areas, the environmental habitat of B. pseudomallei remains unclear.
  
  
  RESULTS
  We performed a large survey in the Darwin area in tropical Australia and screened 809 soil samples for the presence of these bacteria. B. pseudomallei were detected by using a recently developed and validated protocol involving soil DNA extraction and real-time PCR targeting the B. pseudomallei-specific Type III Secretion System TTS1 gene cluster. Statistical analyses such as multivariable cluster logistic regression and principal component analysis were performed to assess the association of B. pseudomallei with environmental factors. The combination of factors describing the habitat of B. pseudomallei differed between undisturbed sites and environmentally manipulated areas. At undisturbed sites, the occurrence of B. pseudomallei was found to be significantly associated with areas rich in grasses, whereas at environmentally disturbed sites, B. pseudomallei was associated with the presence of livestock animals, lower soil pH and different combinations of soil texture and colour.
  
  
  CONCLUSIONS
  This study contributes to the elucidation of environmental factors influencing the occurrence of B. pseudomallei and raises concerns that B. pseudomallei may spread due to changes in land use.
authors.affiliation: Tropical & Emerging Infectious Diseases Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia. mirjam.kaestli@menzies.edu.au
authors.forename: Mirjam
authors.initials: M
authors.lastname: Kaestli
authors.forename: Mark
authors.initials: M
authors.lastname: Mayo
authors.forename: Glenda
authors.initials: G
authors.lastname: Harrington
authors.forename: Linda
authors.initials: L
authors.lastname: Ward
authors.forename: Felicity
authors.initials: F
authors.lastname: Watt
authors.forename: Jason V
authors.initials: JV
authors.lastname: Hill
authors.forename: Allen C
authors.initials: AC
authors.lastname: Cheng
authors.forename: Bart J
authors.initials: BJ
authors.lastname: Currie
mesh_terms: D000818:Animals; D000829:Animals, Domestic / Q000382:microbiology; D001315:Australia / Q000453:epidemiology; D016957:Burkholderia pseudomallei / Q000302:isolation & purification*; D017753:Ecosystem; D008554:Melioidosis / Q000453:epidemiology / Q000382:microbiology*; D012988:Soil Microbiology