Tracing melioidosis back to the source: Using whole-genome sequencing to investigate an outbreak originating from a contaminated domestic water supply

Evan McRobb, Derek S. Sarovich, Erin P. Price, Mirjam Kaestli, Mark Mayo, Paul S Keim, Bart J. Currie

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Melioidosis, a disease of public health importance in Southeast Asia and northern Australia, is caused by the Gram-negative soil bacillus Burkholderia pseudomallei. Melioidosis is typically acquired through environmental exposure, and case clusters are rare, even in regions where the disease is endemic. B. pseudomallei is classed as a tier 1 select agent by the Centers for Disease Control and Prevention; from a biodefense perspective, source attribution is vital in an outbreak scenario to rule out a deliberate release. Two cases of melioidosis within a 3-month period at a residence in rural northern Australia prompted an investigation to determine the source of exposure. B. pseudomallei isolates from the property's groundwater supply matched the multilocus sequence type of the clinical isolates. Whole-genome sequencing confirmed the water supply as the probable source of infection in both cases, with the clinical isolates differing from the likely infecting environmental strain by just one single nucleotide polymorphism (SNP) each. For the first time, we report a phylogenetic analysis of genomewide insertion/deletion (indel) data, an approach conventionally viewed as problematic due to high mutation rates and homoplasy. Our whole-genome indel analysis was concordant with the SNP phylogeny, and these two combined data sets provided greater resolution and a better fit with our epidemiological chronology of events. Collectively, this investigation represents a highly accurate account of source attribution in a melioidosis outbreak and gives further insight into a frequently overlooked reservoir of B. pseudomallei. Our methods and findings have important implications for outbreak source tracing of this bacterium and other highly recombinogenic pathogens.

Original languageEnglish (US)
Pages (from-to)1144-1148
Number of pages5
JournalJournal of Clinical Microbiology
Volume53
Issue number4
DOIs
StatePublished - Apr 1 2015

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Melioidosis
Burkholderia pseudomallei
Water Supply
Disease Outbreaks
Genome
Single Nucleotide Polymorphism
Chronology
Endemic Diseases
Southeastern Asia
Groundwater
Environmental Exposure
Mutation Rate
Phylogeny
Centers for Disease Control and Prevention (U.S.)
Bacillus
Soil
Public Health
Bacteria
Infection

ASJC Scopus subject areas

  • Microbiology (medical)

Cite this

Tracing melioidosis back to the source : Using whole-genome sequencing to investigate an outbreak originating from a contaminated domestic water supply. / McRobb, Evan; Sarovich, Derek S.; Price, Erin P.; Kaestli, Mirjam; Mayo, Mark; Keim, Paul S; Currie, Bart J.

In: Journal of Clinical Microbiology, Vol. 53, No. 4, 01.04.2015, p. 1144-1148.

Research output: Contribution to journalArticle

McRobb, Evan ; Sarovich, Derek S. ; Price, Erin P. ; Kaestli, Mirjam ; Mayo, Mark ; Keim, Paul S ; Currie, Bart J. / Tracing melioidosis back to the source : Using whole-genome sequencing to investigate an outbreak originating from a contaminated domestic water supply. In: Journal of Clinical Microbiology. 2015 ; Vol. 53, No. 4. pp. 1144-1148.
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