Burkholderia pseudomallei, the etiological agent of melioidosis, is a saprophytic bacterium existing endemically in the water and soil of SE Asia and Northern Australia. This organism has shown the ability to remain dormant in its host for decades. B. thailandensis is a closely related non-pathogenic near neighbor that is also found in these soils. It has been suggested that free-living amoeba could be natural reservoirs for these organisms. The interactions of Burkholderia species and Acanthamoeba castellanii, a species of free-living amoeba, were studied to better understand the natural ecology of these organisms and to determine the effects amoeba interactions might have on pathogenesis. In this study, the adherence and persistence of several B. pseudomallei clinical isolates were compared to that of B. thailandensis within both amoeba and a human monocyte cell line. Results showed that B. pseudomallei isolates can enter amoeba and survive therein at varying levels of efficiency. Some isolates were able to persist inside the amoeba for up to three weeks. Optimal entry time into an amoeba trophozoite was found to be about three hours for all ten B. pseudomallei isolates. Interestingly, it was found that after internalization by amoeba, B. pseudomallei have a significantly increased ability to both attach to, and grow within human monocytes, suggesting that such interactions increase the virulence capabilities of soil isolates.



College and Department

Life Sciences; Microbiology and Molecular Biology



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amoeba, virulence, Burkholderia, Acanthamoeba castellanii

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Microbiology Commons