Groundwater seeps facilitate exposure to Burkholderia pseudomallei
Baker, A and Tahani, D and Gardiner, C and Bristow, KL and Greenhill, AR and Warner, J, Groundwater seeps facilitate exposure to Burkholderia pseudomallei, Applied and Environmental Microbiology, 77, (20) pp. 7243-7246. ISSN 0099-2240 (2011) [Refereed Article]
Burkholderia pseudomallei is a saprophytic bacterium which is the causative agent of melioidosis, a common cause of fatal bacterial pneumonia and sepsis
in the tropics. The incidence of melioidosis is clustered spatially and temporally and is heavily linked to rainfall and extreme
weather events. Clinical case clustering has recently been reported in Townsville, Australia, and has implicated Castle Hill,
a granite monolith in the city center, as a potential reservoir of infection. Topsoil and water from seasonal groundwater
seeps were collected around the base of Castle Hill and analyzed by quantitative real-time PCR targeting the type III secretion
system genes for the presence of B. pseudomallei. The organism was identified in 65% (95% confidence interval [CI], 49.5 to 80.4) of soil samples (n = 40) and 92.5% (95% CI, 83.9 to 100) of seasonal groundwater samples (n = 40). Further sampling of water collected from roads and gutters in nearby residential areas after an intense rainfall event
found that 88.2% (95% CI, 72.9 to 100) of samples (n = 16) contained viable B. pseudomallei at concentrations up to 113 CFU/ml. Comparison of isolates using multilocus sequence typing demonstrated clinical matches
and close associations between environmental isolates and isolates derived from clinical samples from patients in Townsville.
This study demonstrated that waterborne B. pseudomallei from groundwater seeps around Castle Hill may facilitate exposure to B. pseudomallei and contribute to the clinical clustering at this site. Access to this type of information will advise the development and
implementation of public health measures to reduce the incidence of melioidosis.