<i>Burkholderia</i><i>pseudomallei</i>Type G in Western Hemisphere

Gee, Jay E.; Allender, Christopher John; Tuanyok, Apichai; Elrod, Mindy G.; Hoffmaster, Alex R.

doi:10.3201/eid2004.130960

Cited by 25 publications

(36 citation statements)

References 6 publications

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“…A recent analysis of strains from the Caribbean, Central and South America showed a consistent presence of the to-date otherwise uncommon type G pattern in the 16S-23S internal transcribed spacer of B. pseudomallei. 31 This type G pattern has also been found in strains from Africa and it was proposed that these findings were consistent with the hypothesis that the type G isolates may reflect a bottleneck that occurred during the dispersal of B. pseudomallei from Southeast Asia to the rest of the world. However, MLST analysis of strains with the type G pattern shows considerable diversity and most recently two confirmed autochthonous cases of human melioidosis in Madagascar and a third case in a traveler infected in Madagascar each had novel MLST sequence types.…”

Section: Global Distribution Of Melioidosis: Recent Expansion or Justsupporting

confidence: 79%

Melioidosis: Evolving Concepts in Epidemiology, Pathogenesis, and Treatment

Currie

2015

Semin Respir Crit Care Med

265

339

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Infection with Burkholderia pseudomallei can result in asymptomatic seroconversion, a single skin lesion that may or may not heal spontaneously, a pneumonia which can be subacute or chronic and mimic tuberculosis or rapidly progressive resulting in fatal overwhelming sepsis. Latency with subsequent activation of disease is well recognized, but very uncommon. Melioidosis also has a myriad of other clinical presentations and diagnosis is often delayed because of this and because of difficulties with laboratory diagnosis and lack of recognition outside melioidosis-endemic regions. The perception of B. pseudomallei as a top tier biothreat agent has driven large funding for research, yet resources for diagnosis and therapy of melioidosis in many endemic locations remain extremely limited, with mortality as high as 50% in comparison to around 10% in regions where state-of-the-art intensive care therapy for sepsis is available. Fatal melioidosis is extremely unlikely from natural infection in a healthy person, provided the diagnosis is made early, ceftazidime or meropenem is commenced and intensive care therapy is available. While biothreat research is directed toward potential aerosol exposure to B. pseudomallei, the overall proportion of melioidosis cases resulting from inhalation rather than from percutaneous inoculation remains entirely uncertain, although the epidemiology supports a shift to inhalation during severe weather events such as cyclones and typhoons. What makes B. pseudomallei such a dangerous organism for patients with diabetes and other selective risk factors remains unclear, but microbial genome-wide association studies linking clinical aspects of melioidosis cases to nonubiquitous or polymorphic B. pseudomallei genes or genomic islands are beginning to uncover specific virulence signatures. Finally, what also remains uncertain is the global phylogeography of B. pseudomallei and whether melioidosis is spreading beyond historical locations or is just being unmasked in Africa and the Americas by better recognition and increased surveillance.

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Section: Global Distribution Of Melioidosis: Recent Expansion or Justsupporting

confidence: 79%

Melioidosis: Evolving Concepts in Epidemiology, Pathogenesis, and Treatment

Currie

2015

Semin Respir Crit Care Med

265

339

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“…comm.) ( 5 ). The ITS type CE and the location of this subclade support an origin outside the Western Hemisphere, more likely in Asia, which supports the earlier proposal that PB08298010 might have resulted from exposure to contaminated medical supplies from Southeast Asia ( 10 , 36 ).…”

Section: Discussionmentioning

confidence: 99%

Phylogeography ofBurkholderia pseudomalleiIsolates, Western Hemisphere

Gee¹,

Gulvik²,

Elrod³

et al. 2017

Emerg. Infect. Dis.

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The bacterium Burkholderia pseudomallei causes melioidosis, which is mainly associated with tropical areas. We analyzed single-nucleotide polymorphisms (SNPs) among genome sequences from isolates of B. pseudomallei that originated in the Western Hemisphere by comparing them with genome sequences of isolates that originated in the Eastern Hemisphere. Analysis indicated that isolates from the Western Hemisphere form a distinct clade, which supports the hypothesis that these isolates were derived from a constricted seeding event from Africa. Subclades have been resolved that are associated with specific regions within the Western Hemisphere and suggest that isolates might be correlated geographically with cases of melioidosis. One isolate associated with a former World War II prisoner of war was believed to represent illness 62 years after exposure in Southeast Asia. However, analysis suggested the isolate originated in Central or South America.

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“…The Wallace Line is a major biogeographic barrier between Asia and Australia that has led to restricted genetic flow among the flora and fauna between these two regions. Other studies have since affirmed the ancestral nature of Australian B. pseudomallei and the rare historical transmission of B. pseudomallei from Australia to Asia (6,15). The ancient separation of these two populations has enabled a strong phylogeographic signal between Asian and Australian clades to evolve despite high levels of recombination across the B. pseudomallei genome (4,6).…”

Section: Discussionmentioning

confidence: 99%

“…Lower-resolution genotyping methods, such as multilocus sequence typing (MLST) (10)(11)(12)(13) and 16S internal transcribed spacer typing (14), support the continental separation of B. pseudomallei observed on the genomic level (see, e.g., references 5 and 15), and these molecular tools have proven useful for source tracing B. pseudomallei in regions that are nonendemic for the organism (14,15). However, these genotyping methods have their limitations, as evidenced by a recent study in which two multilocus sequence types (STs) shared between Australia and Cambodia were found to be genetically unrelated on the whole-genome level (7).…”

mentioning

confidence: 99%

Unprecedented Melioidosis Cases in Northern Australia Caused by an Asian Burkholderia pseudomallei Strain Identified by Using Large-Scale Comparative Genomics

Price

Sarovich

Smith

et al. 2016

Appl Environ Microbiol

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Melioidosis is a disease of humans and animals that is caused by the saprophytic bacterium Burkholderia pseudomallei. Once thought to be confined to certain locations, the known presence of B. pseudomallei is expanding as more regions of endemicity are uncovered. There is no vaccine for melioidosis, and even with antibiotic administration, the mortality rate is as high as 40% in some regions that are endemic for the infection. Despite high levels of recombination, phylogenetic reconstruction of B. pseudomallei populations using whole-genome sequencing (WGS) has revealed surprisingly robust biogeographic separation between isolates from Australia and Asia. T he Gram-negative soil-dwelling bacterium Burkholderia pseudomallei is the etiologic agent of melioidosis, an often deadly tropical disease that can be difficult to diagnose, particularly in nonendemic or resource-poor regions where cases are not expected and appropriate microbiological diagnostic tools are not readily available (1). Diabetics are particularly susceptible to melioidosis. B. pseudomallei infection can be acquired from contaminated soil or water by percutaneous inoculation, inhalation, aspiration, or ingestion, and no vaccine targeting this organism is available (2). In 2012, B. pseudomallei was reclassified by U.S. federal agencies as a tier 1 select agent, the highest risk category for a biological entity, due to concerns that this bacterium would pose a severe threat to humans and animals in the event of its deliberate misuse (3).The B. pseudomallei genome exhibits high homologous recombination rates. On a per-allele basis, recombination is estimated to occur between 18 and 30 times more frequently than mutation (4). This extensive lateral gene transfer can confound population analyses, particularly those that are based on studying limited geographic regions (e.g., the Northern Territory, Australia [5]) due to high rates of homoplasy observed among genetic variants. In contrast, genomic analyses of B. pseudomallei populations on a continental scale have revealed a clear separation of B. pseudomallei isolates between Asia and Australia (4, 6, 7). Bayesian analysis of B. pseudomallei genome variation points to an ancient separation, with migration out of Australia into Asia occurring tens of thousands of years ago during the Pleistocene (4). The rarity of pathogen movement is due largely to one factor: new melioidosis cases almost always result from bacterial infection acquired from the local environment, with human-to-human and zoonotic transmission of this pathogen being exceedingly rare (8). In support of the rarity of B. pseudomallei movement across major biogeographic boundaries, the definitive transmission of B. pseudomallei from Asia into Australia has not yet been observed. Nevertheless, melioidosis cases imported into nonendemic locations via travelers are being increasingly reported, as is recognition of locations that are endemic for melioidosis outside the classical regions of Southeast Asia and Australia (9). With modern global tra...

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BurkholderiapseudomalleiType G in Western Hemisphere

Cited by 25 publications

References 6 publications

Melioidosis: Evolving Concepts in Epidemiology, Pathogenesis, and Treatment

Melioidosis: Evolving Concepts in Epidemiology, Pathogenesis, and Treatment

Phylogeography ofBurkholderia pseudomalleiIsolates, Western Hemisphere

Unprecedented Melioidosis Cases in Northern Australia Caused by an Asian Burkholderia pseudomallei Strain Identified by Using Large-Scale Comparative Genomics

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