One of my favourite microorganisms, viz., Burkholderia pseudomallei (the cause of Melioidosis)

As a young pathology trainee I remember reading about this mysterious bacterium and the disease it caused. I wasn’t far into my training when one morning I found a rapidly motile bacillus in a wet preparation from the blood culture bottle from a young man in our spinal unit with bacteræmia. The patient was from Cairns. He’d ridden his motorcycle off a cliff and landed in some mud. He had a fractured spine and a bad burn on his leg from the motorcycle’s exhaust pipe. The Gram’s stain from the blood culture bottle revealed a thin Gram-negative bacillus with a bipolar staining pattern. At the time I assumed it would be a Pseudomonas aeruginosa, a common enough finding in spinal patients with indwelling (urinary) catheters. The following morning the colonial morphology on horse blood agar and MacConkey were not typical for Ps. aeruginosa. The bacterium was oxidase positive but there was no green pigmentation. I set up an API 20E and API 20NE. The following day the colonial morphology was very odd, the colonies had become wrinkled and dry. It hit me then that this was likely to be either Burkholderia pseudomalleiBurkholderia cepacia or Pseudomonas stutzeri. The patient’s history suggested he was bacteræmic and had Melioidosis with the portal of entry being the leg burn that was exposed to mud in which B. pseudomallei could be found. B. pseudomallei is commonly found in Northern Australia including far north Queensland.

As my training in Brisbane was coming to an end at the Princess Alexandra Hospital, we experienced a summer of really heavy rainfall. I remember two patients with Melioidosis who had never travelled further north than Brisbane. I was told by a very senior microbiologist that when the Brisbane was first settled an awful lot of horses where buried. Whenever there was really heavy rain, for example, associated with a tropical low or tropical cyclone occasional cases of Melioidosis would emerge. I really have no way of verifying that story, but I know that in subequatorial and tropical climes monsoonal rains which raise the water table brought cases of Melioidosis usually within 10 to 14 days. This was a constant event at the beginning of the ‘wet’ when I was living and working in Darwin.

When I moved to Darwin in February 1996 I grew to love this bacterium and the disease it caused.

For some very basic facts about the bacterium, the disease, how we diagnose it and treat it I’ve created a little presentation. You can view it as a PDF.

During my time in Darwin I learnt so much from the preeminent clinician and scientist in Melioidosis, viz., Prof. Bart Currie. If you enter “Currie and Melioidosis” into a search engine you’ll see he’s authored hundreds of articles in high impact peer reviewed medical and scientific journals. I managed to get involved a couple of times in contributing to the American Society for Microbiology’s Manual of Clinical Microbiology’s Burkholderia chapters.

  1. Gilligan, P. H., G. Lum, P. Vandamme, and S. Whittier.  Burkholderia, Stenotrophomonas, Ralstonia, Brevundimonas, Comamonas, Pandoraea and Acidovorax.  Manual of Clinical Microbiology.  Eighth edition.  ASM Press, Washington D.C.  2003.
  2. LiPuma J., P. Vandamme, and G. Lum. Burkholderia, Stenotrophomonas, Ralstonia, Cupriavidus, Brevundimonas, Comamonas, Delftia, Pandoraea, and Acidovorax Manual of Clinical Microbiology.  Ninth edition.  ASM Press, Washington D.C.  2007.

When I changed jobs and moved to Canberra and the Australian Government’s Department of Health and Ageing my engagement with the B. pseudomallei community was confined to some specialist groups. My biggest thrill though was to be able to talk about B. pseudomallei before senators at Senate Estimates in 2011.

Senate Estimates Hansard Community Affairs 31 May 2011 Check out from page 152 of the document for my responses to the Senators’ questions.

One day I’ll write about my favourite bacterium, viz., Chromobacterium violaceum.