Skip to content

Advertisement

BMC Infectious Diseases

Open Access
Open Peer Review

This article has Open Peer Review reports available.

How does Open Peer Review work?

Multilocus sequence types of clinical Burkholderia pseudomallei isolates from peninsular Malaysia and their associations with disease outcomes

BMC Infectious DiseasesBMC series – open, inclusive and trusted201818:5

https://doi.org/10.1186/s12879-017-2912-9

Received: 24 March 2017

Accepted: 13 December 2017

Published: 2 January 2018

Abstract

Background

Previous studies on the Burkholderia pseudomallei genetic diversity among clinical isolates from melioidosis-endemic areas have identified genetic factors contributing to differential virulence. Although it has been ruled out in Australian and Thai B. pseudomallei populations, it remains unclear whether B. pseudomallei sequence types (STs) correlate with disease in Malaysian patients with melioidosis.

Methods

In this study, multi-locus sequence typing (MLST) was performed on clinical B. pseudomallei isolates collected from Kelantan state of Malaysia, patients’ clinical data were reviewed and then genotype-risk correlations were investigated.

Results

Genotyping of 83 B. pseudomallei isolates revealed 32 different STs, of which 13(40%) were novel. The frequencies of the STs among the 83 isolates ranged from 1 to 12 observations, and ST54, ST371 and ST289 were predominant. All non-novel STs reported in this study have also been identified in other Asian countries. Based on the MLST data analysis, the phylogenetic tree showed clustering of the STs with each other, as well as with the STs from Southeast Asia and China. No evidence for associations between any of B. pseudomallei STs and clinical melioidosis presentation was detected. In addition, the bacterial genotype clusters in relation with each clinical outcome were statistically insignificant, and no risk estimate was reported. This study has expanded the data for B. pseudomallei on MLST database map and provided insights into the molecular epidemiology of melioidosis in Peninsular Malaysia.

Conclusion

This study concurs with previous reports concluding that infecting strain type plays no role in determining disease presentation.

Keywords

Burkholderia pseudomalleiMelioidosisMLSTSequence typeRisk

Background

Burkholderia pseudomallei (agent of melioidosis) is acquired by inoculation, inhalation and ingestion routes. It causes wide spectrum clinical presentations; particularly in patients with diabetes mellitus [1]. Marked heterogeneity is observed in the clinical presentation and disease severity among patients. The most severe manifestations of melioidosis are pneumonia and severe sepsis [2]. Melioidosis predominates in Southeast Asia and northern Australia [3, 4]. Regional variations in melioidosis signs and symptoms have been reported and prostatic abscess and encephalomyelitis are common in Australians. Parotid abscesses and hepatosplenic suppuration presentations have been described frequently in Thailand [57]. There is good evidence that certain B. pseudomallei genes contribute to different clinical presentations between Asia and Australia; in particular, the bimABm gene, which has been strongly associated with neurological melioidosis [8]. The reason behind this diversity remains unclear, but it may be due to host, bacterial, or environmental factors [2].

The study of molecular epidemiology has provided additional details regarding bacterial diversity and distribution [3]. Commonly applied B. pseudomallei molecular epidemiology procedures include pulsed-field gel electrophoresis (PFGE) [9, 10], random amplification of polymorphic DNA (RAPD) [11], ribotyping [12] and whole genome sequencing [13]. Multi-locus sequence typing (MLST) is another molecular approach that simplifies the exchange of local and global inter-laboratory genotyping data [14]. The discriminating ability of MLST between different B. pseudomallei genotypes was evaluated previously by comparison with PFGE and similar results were reported [2].

Typing of B. pseudomallei using MLST scheme is useful to explore sequence types (STs) in particular populations [15], predict the distribution of bacterial STs in a given geographical area [16], track the source of melioidosis outbreaks [17] and define whether recurrent melioidosis is due to a relapse of the same bacterial ST or reinfection with a different ST [18].

The B. pseudomallei STs must be studied in Peninsular Malaysia to understand the population genetics in this region and to determine the distribution and frequency of genotype associations in melioidosis cases. MLST was applied for this purpose. According to a literature database search, no national or local project has applied MLST to B. pseudomallei isolates collected from Peninsular Malaysia. However, some genotyping studies have used pooled isolates from different regions of Southeast Asia, including Malaysia [19]. Thus, this is the first study to compare STs of clinical isolates from Peninsular Malaysia and to determine whether particular STs are associated with particular clinical outcomes.

Methods

B. pseudomallei isolates source

Clinical samples were collected, bacteria were isolated and B. pseudomallei was identified and archived as part of routine diagnostics in accordance to the standard protocol at the Medical Microbiology & Parasitology Laboratory at the Hospital Universiti Sains Malaysia (HUSM). Only a single clinical isolate from each patient was obtained to preserve the assumption of independence of observations and to avoid repetition.

Multi-locus sequence typing

MLST was performed as described previously by Godoy et al. [19]. New allelic profiles were confirmed by a repeated MLST procedure. Novel STs were assigned new allelic profile numbers and were submitted, with the isolate information to the Burkholderia MLST database (http://pubmlst.org/bpseudomallei/). The submission process was completed from November 2012 to April 2015.

Phylogenetic analysis

Basic statistical quantities such as number of alleles, number of variable sites per allele, number and frequency of single nucleotides polymorphism (SNPs) in each locus and the nucleotide sequence diversity rate were calculated and displayed using functional options in molecular evolutionary genetics analysis version-6 (MEGA 6) software [20]. Relatedness among isolates was estimated based on two principles: differences in allelic profiles using eBURST v7 [21, 22]. and differences in the concatenated sequence of alleles at all loci using MEGA 6 software.

All STs were uploaded into eBURST v7 software to display the relatedness among the isolates obtained in this study, as well as among B. pseudomallei of the historical collection from different regions in Malaysia. Three population snapshot diagrams were generated: the first diagram displayed the relatedness of the novel and existing STs reported in this study. The second and third diagrams were made for STs of the MLST database for Malaysia before and after the addition of STs obtained from this study to display the significant changes on the full-size Malaysian MLST database population snapshot.

Sequences of every allelic profile were joined in the order of loci used to define the allelic profile to achieve a concatenated sequence of 3399 bp. The topology and grouping of all STs retrieved from this study were displayed on the constructed bootstrapped phylogenetic trees using Unweighted Pair Group Method with Arithmetic average (UPGMA) method in MEG 6 software. STs obtained from this study were analyzed with selected 88 STs representing Malaysia and regional endemic countries including India, China, Singapore, Indonesia, Laos, Vietnam, Philippines, Bangladesh and Thailand.

Genotype-disease associations

Patient records were reviewed for specific clinical manifestations and disease outcomes, including types of melioidosis (bacteremic, nonbacteremic, disseminated or localized), organs involved (lungs, liver, spleen, bone, soft tissues, brain and genitourinary) and death. All clinical definitions and classifications were categorized as mentioned by Zueter et al. [23]. Strain tropism and virulence were studied by displaying clinical outcomes throughout the phylogenetic tree topology prepared from the STs. On the other hand, all closely-related STs were gathered into groups and analyzed as independent variables (predictors) against clinical outcomes that were identified as dependent variables. Statistical analyses were performed to analyze each genotype cluster with every clinical outcome using Pearson’s chi-square or Fisher exact tests.

Ethics statement

Ethical approval was obtained from the Universiti Sains Malaysia Research Ethics Committee (Human) (USM/JEPeM/15110495) and data were analyzed anonymously.

Results

Of the 83 clinical B. pseudomallei isolates obtained in this study, 32 STs were identified. The frequencies of STs among the 83 isolates were 1–12 observations with a predominance of ST54 (n = 12), ST371 (n = 7) and ST289 (n = 7).

Among the obtained STs, the number of alleles per locus varied from 3 to 6. SNPs were observed at all seven loci, with the number of SNPs ranging from 2 to 21, while the number of polymorphic (variable) sites within the different alleles at the seven loci varied between 2 and 15. The levels of locus sequence diversity among all 32 STs were 2.5 to 5.3% (Table 1). All STs identified in this study were deposited in the MLST database with complete reference annotation (Table 2).
Table 1

Properties of the MLST loci in the clinical B. pseudomallei isolates from Peninsular Malaysia

Locus

No. of nucleotides analyzed

No. of alleles

No. of SNP

SNP Frequencya

No. of variable sites

Sequence diversity rateb

Ace

519

4

3

0.6%

3

4.1%

gltB

522

5

8

1.5%

3

3.1%

gmhD

468

5

12

2.5%

5

4.0%

lepA

486

6

21

4.3%

15

5.3%

lipA

402

5

7

1.7%

4

2.9%

narK

561

4

9

1.6%

5

3.3%

Ndh

443

3

2

0.5%

2

2.5%

aRate of SNPs diversity in relation with locus length (no. of SNP/locus length)

bRate of allele diversity in relation with the number of total referenced database alleles

Table 2

Properties of B. pseudomallei sequence types in this study

Isolate code

Origin (specimen)

Sequence type

 

Strain name

MLST database ID

2

Blood

54

USM2

3668

3

Blood

54

USM3

3669

7

Pus

54

USM7

3670

15

Body fluid

54

USM15

3671

69

Blood

54

USM69

4066

47

Pus

54

USM47

3672

48

Blood

54

USM48

3673

50

Blood

54

USM50

3674

43

Urine

54

USM43

3675

22

Body fluid

54

USM22

3676

27

Body fluid

54

USM27

3677

40

Blood

54

USM40

3678

8

Blood

371

USM8

3679

12

Blood

371

USM12

3718

14

Blood

371

USM14

3680

24

Blood

371

USM24

3681

33

Blood

371

USM33

3682

35

Blood

371

USM35

3683

71

Blood

371

USM71

4018

6

Pus

46

USM6

3684

45

Sputum

46

USM45

3685

20

Blood

46

USM20

3686

57

Blood

46

USM57

3687

32

Blood

46

USM32

3688

61

Pus

46

USM61

3689

39

Blood

84

USM39

3690

9

Pus

84

USM9

3691

28

Body fluid

84

USM28

3692

64

Blood

84

USM64

3693

42

Blood

289

USM42

3694

44

Blood

289

USM44

3695

49

Blood

289

USM49

3696

13

Blood

289

USM13

3697

5

Blood

289

USM5

3698

66

Pus

289

USM66

4016

63

Blood

289

USM63

3699

29

Blood

271

AMON29

3714

74

Blood

271

USM74

4025

78

Blood

271

USM78

4026

79

Blood

271

USM79

4027

36

Blood

306

USM36

3700

53

Pus

306

USM306

3701

58

Blood

306

USM58

3702

37

Pus

306

USM37

3703

10

Blood

55

USM10

3708

23

Blood

55

USM23

3709

18

Pus

50

USM18

3704

51

Sputum

50

USM51

3705

54

Blood

50

USM54

3706

41

Blood

50

USM41

3707

38

Blood

376

USM38

3710

17

Pus

376

USM17

3711

31

Pus

507

HANA31

3713

46

Blood

51

ZED46

3712

60

Body fluid

10

USM60

4015

67

Blood

164

USM67

4022

73

Blood

164

USM73

4023

80

Blood

164

USM80

4024

68

Blood

369

USM68

4017

72

Blood

402

USM72

4019

82

Blood

368

USM82

4021

75

Blood

47

USM75

4028

77

Blood

47

USM77

4029

81

Blood

47

USM81

4030

83

Pus

47

USM83

4031

76

Blood

168

USM76

4020

11

Blood

1319

11

3659

65

Blood

1319

USM65

4067

1

Blood

1317

1

3657

4

Blood

1318

4

3658

19

Blood

1320

19

3660

21

Blood

1321

21

3661

25

Body fluid

1322

25

3662

26

Body fluid

1322

AMAR26

3715

30

Pus

1323

30

3663

16

Blood

1323

USM16

4014

34

Blood

1324

34

3664

52

Body fluid

1325

52

3665

55

Blood

1326

55

3666

56

Blood

1326

HAMZ56

3716

59

Blood

1327

59

3667

62

Pus

1358

ABD12

4032

70

Body fluid

1359

NOR13

4033

Genetic relatedness among studied B. Pseudomallei sequence types

Half of the STs were clustered into a single group of 16 STs, of which four were novel (Fig. 1). The STs were presented in 44 isolates clustered into a major group and emerged from ST271 representing the predicted founder. An additional three subgroup founders branched from ST271 were also identified including ST50, ST369 and ST1317. ST84 was the predicted as ancestor to another smaller population group consisting of six STs, and most were novel. The remaining STs were singletons.
Fig. 1

eBURST diagram representing the relatedness between 32 STs identified in 83 isolates. Black dot: existing ST. Red dot: novel ST. Blue dot: predicted group ancestor. Yellow dot: predicted subgroup ancestor. Green dot: novel and subgroup ancestor ST. Black and purple lines: single locus variants (SLVs). Blue line: double locus variant (DLV). Re-samplings for bootstrapping = 10,000; minimum number of identical loci for group definition =6; minimum number of SLV for subgroup definition =3. The size of the dot reflects the individual ST frequency among the 83 strains

Genetic relatedness among B. Pseudomallei sequence types in Malaysia

Thirteen STs identified in this study were novel, including ST1317, ST1318, ST1319, ST1320, ST1321, ST1322, ST1323, ST1324, ST1325, ST1326, ST1327, ST1358 and ST1359. On the other hand, the other STs (n = 19) reported in this study were also characterized elsewhere in the Indian subcontinent, China and Southeast Asia.

Total of 264 B. pseudomallei isolates and 59 STs were already registered in the database (MLST.net) until April 2015, all of which were from Malaysia. The present study uploaded additional 83 B. pseudomallei isolates and 32 STs from the same country. Before the present study, almost half of Malaysian STs were clustered into a single group with ST50 as the predicted founder. The remaining STs were singletons. No sub-groups were reported (Fig. 2). The present study has expanded the former Malaysian clonal cluster by adding more branching STs. In addition, new clonal expansion has emerged from ST84 to create another group in the Malaysian database (Fig. 3). This expansion was characterized by conversion of ST84 from an existing ST into a new ancestral group founder from which other single and double locus variant STs have emerged. In addition, another sub-clonal expansion was created from ST51, ST271, ST46, ST369 and ST1317.
Fig. 2

eBURST population snapshot for B. pseudomallei STs in Malaysia before conducting the present study. Blue dot refers to group founder. Each black dot represents single genotype. The size of the dot represents the ST frequency

Fig. 3

Overall B. pseudomallei STs in Malaysia showing STs added by this study. Black dot: ST only in Malaysian database query. Red hollow: ST only in this study. Green hollow: ST in both Malaysian query and present study. Yellow dot: subgroup founder. Blue dot: Group founder. Re-samplings for bootstrapping = 10,000; minimum number of identical loci for group definition =6; minimum number of SLV for subgroup definition =3. The size of the dot reflects the individual ST frequency among the 83 strains

Phylogenetic relationship among regional B. Pseudomallei sequence types

The majority of the STs formed unique sequences that differed by at least a single nucleotide and almost all were seen in all groups in the phylogenetic tree (Fig. 4). More than half of the group 1 STs were clustered with each other, as well as with STs from Malaysia, Thailand, Singapore, Cambodia, Vietnam, Laos and China. On the other hand, ST50 and the novel ST1327 were not grouped with any of our STs but were clustered with local STs and with narrower regional STs located in groups 2 and 8, respectively. The remaining STs were distributed among other groups with little distance between them. The STs in the lower sub-cluster of group 4 and in group 5 were clustered with STs that have been reported from Sarawak in West Malaysia. The majority of the novel STs were clustered with each other in any given group. Of the 13 novel STs, eight were located in group one. The only unique ST in this study was ST1326, which was novel and a singleton.
Fig. 4

The evolutionary history inferred using the UPGMA method to analyze the studied 32 STs along with 88 historical STs represented India, China and Southeast Asian countries.▲: Sarawak ST

B. pseudomallei genotype - disease associations

The clinical histories of 70 subjects in whom bacterial genotypes were identified and archived were reviewed from 2007 to 2014. No evidence supporting an association between B. pseudomallei STs and any clinical presentation of melioidosis was observed on the phylogenetic tree; no clustering was noted for a given clinical outcome with a particular genotype (Fig. 5).
Fig. 5

Topology of clinical outcomes on phylogenetic tree. MM: multifocal melioidosis, LM: localized melioidosis, NM: nonbacteremic melioidosis, TS: transient septicemia. 1: first genotype cluster; 2: second genotype cluster; 3: third genotype cluster; 4: fourth genotype cluster

In addition, no evidence of differential virulence or strain tropism was detected. For example, severe sepsis (n = 11) was caused by strains of seven different STs, whereas septic shock (n = 29) and abscess (n = 30) were caused by strains of 17 and 18 different STs, respectively.

The two-way tables for all bacterial genotype clusters in relation to clinical outcome variables were statistically non-significant (p > 0.05), with no reported risk estimate for any genotype cluster developing any of the clinical outcome (data not shown).

Discussion

Burkholderia pseudomallei is Gram negative saprophytic bacterium classified as Tier 1 Biological Select Agent [24]. Due to frequent recombination, the B. pseudomallei genome showed high plasticity that increases genetic divergence, and therefore strain-to-strain variation [25]. The spectrum of B. pseudomallei genetic diversity in Peninsular Malaysia and its association with clinical outcomes is not yet known. It is therefore important to determine ST genotypes to compare the molecular epidemiology of B. pseudomallei in Peninsular Malaysia with strains obtained from other regions, especially other countries within Asia, and to investigate genotype diversity as a possible explanation for differences in disease presentation, treatment response, prognosis and mortality [26].

In the present study, STs were identified with different frequencies, predominance, novelty, and allelic heterogeneity. The overall diversity of isolates found in the clinical specimens was 0.38 STs/isolate, compared with a diversity ratio of 0.65 STs/isolate reported in Australia.26 Several molecular studies that applied various genotyping methods to clinical B. pseudomallei isolates reported genotypic novelty and diversity with or without predominance of particular genotypes among single population communities of temperate endemic areas of Malaysia [10, 15, 2729], Thailand [9, 30], India [31], and Australia [2, 32].

The presence of different genotypes with various frequencies reflects the historical introduction and dissemination of different B. pseudomallei genotypes into the study area or due to expansion of local STs that yielded new strains with novel STs [33]. Genotypic predominance might be attributed to localization of a particular genotype in the study area in which the contaminated environment became a rich source for infection by that genotype [34]. For example, the predominant STs found in this study were ST54, ST371, ST46 and ST84, which have been found in Malaysia and neighbouring countries. Moreover, some genotypes identified in this study such as ST402, ST55, ST271, ST376, ST47, and ST376, have been identified in soil and water sources in Malaysia and other neighboring countries [19, 33].

This genotypic picture for our clinical isolates might be linked to the endemic geographical distribution of B. pseudomallei in the environments our patients resided. This suggestion is supported by reports of melioidosis outbreaks caused by B. pseudomallei of the same genotypes as those of the suspected environmental sources [16, 3538].

The presence of novel genotypes indicates local persistence of B. pseudomallei in the same geographical area and their ability to establish a new clone series producing novel offspring’s that carry new genotypes [39]. Several reports have documented the emergence of novel B. pseudomallei genotypes regardless of the number of the genotyped isolates [15, 31]. In this study, two of 10 strains isolated from patients residing in Bachok were novel genotypes, whereas 3/15 (20%), 1/10 (10%), 2/8 (25%) and 2/4 (50%) strains carried novel genotypes in Terengganu, Selangor, Pasir Puteh and Machang, respectively.

The characteristics of the alleles and loci were considerably diverse among the 32 STs. However, no new alleles have been reported. Previous studies suggested a high rate of recombination replacement relative to substitution mutations in B. pseudomallei that caused re-assortment of existing alleles, rather than emergence of new alleles, leading to a new generation of STs [32, 39].

The changes occurring in ST84 (as seen in the eBURST snapshots) before and after this study suggest the occurrence of clonal expansion of ST84. This conclusion was reached based on the presence of seven novel STs arising from ST84 and would be supported by confirming the evolutionary convergence of ST84 from a singleton ST to the group founder ST. In the same way, other sub-clonal expansions were created from ST51, ST271, ST46, ST369, and ST1317. Thus, the present study has markedly expanded the former Malaysian clonal cluster by adding more branching STs.

McCombie et al. [33] had studied the molecular epidemiology of B. pseudomallei using MLST of 207 historical isolates collected in Malaysia, Thailand and Vietnam. MLST revealed 80 STs and 56 were novel. When those STs were added to the B. pseudomallei MLST database and analyzed together, the historical-collection STs clustered significantly within the complex of the eBURST diagram in an ancestral pattern and expanded the B. pseudomallei population snapshot. In the same study, ST84 was likely a B. pseudomallei isolate characteristic of Southeast Asia rather than Australia based on abundance in several environmental isolates from Thailand and Malaysia.

Clustering of our STs in the phylogenetic tree with STs from Sarawak, Thailand, Singapore, Cambodia, Vietnam, Laos and China suggests their genetic relatedness with ST ancestors of these regions. In addition, all non-novel STs identified in this study were also identified in these countries at different frequencies, which suggesting that the Malaysian isolates may not be distinct from those of Southeast Asia. ST371, ST164, ST47, ST306, ST55, ST376, ST402, ST507, ST368, ST369, ST10 and ST168 were first identified in Malaysia. Nevertheless, these STs are not found exclusively in Malaysia only but also in other Southeast Asian countries. This topology explores the geographical expansion and spread of those STs among regional countries through environmental and human routes [32]. Such expansion was restricted to countries bordering with Malaysia but not other regions, such as Australia, Africa, or Latin America, due to the absence of shared STs with those regions, which concurs with previous findings of no shared STs among different continents. However, a few exceptions have been more recently reported; in one study, ST105 and ST849 were shared STs between Australia and Cambodia and both STs were isolated from patients from both countries [40]. Another study reported the isolation of ST562 from Australia and China [41].

Clinical outcome-genotyping association in human cases has not been clearly described in Malaysia and interpretative studies on the significance of genotyping results remain limited. In this study, tests to cluster clinical presentation on the phylogenetic tree, differential virulence tropism for an individual ST, and statistical associations between genotype clusters with clinical presentations did not detect any relationship between genotype and disease. Two Australian studies genotyped clinical isolates of B. pseudomallei using PFGE and MLST. The clinical history of each patient was reviewed and analyzed statistically in combination with the resulting genotypes. However, neither study found an association due to the high diversities of the genotypes and clinical presentations and low relative frequencies of each of them. In addition, no association was reported between a given genotype and a particular clinical presentation or site of infection [2, 26]. On the other hand, a study from Thailand reported partial and possible associations between B. pseudomallei ribotypes and clinical outcomes of melioidosis. However, that study was not conclusive due to low number of tested cases [11]. Our study concurs with the previous studies demonstrating a lack of an association between any ST and disease, but considers that host and environmental factors are reasons for the heterogenous nature of the clinical presentation of the disease.

Conclusion

The present study revealed the high diversity of B. pseudomallei in Malaysia, and several STs were discovered. Many of the non-novel STs found in this study were also reported from neighboring Asian countries. None of the STs were associated a specific disease presentation. Therefore, host and environmental factors play crucial roles in the diversity of clinical presentation and outcomes of the disease. Further studies on environmental samples (and a comparison with clinical isolates) may provide more extensive, representative data to elucidate the course and evolution of the B. pseudomallei population in this region. Expanding the clinical case review would provide more data for further understanding of specific genotype-disease association in melioidosis.

Abbreviations

MEGA: 

Molecular evolutionary genetics analysis

MLST: 

Multi-locus sequence typing

PCR: 

Polymerase chain reaction

PFGE: 

Pulsed-field gel electrophoresis

RAPD: 

Random amplification of polymorphic DNA

SNP: 

Single nucleotides polymorphism

ST: 

Sequence type

UPGMA: 

Unweighted Pair Group Method with Arithmetic average

Declarations

Acknowledgements

We thank Azlan Abdullah and Nurleem Mursheed from the Microbiology Laboratory USM for their help procuring the isolates and help with technical issues.

Funding

This project was funded by Malaysian Ministry of Education Exploratory Research Grant Scheme (ERGS) grant, no. 203/PPSP/6730024 awarded to Azian Harun. The funding body has a role in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript.

Availability of data and materials

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Authors’ contributions

AZ: did data collection, analyzed and drafted the article; ZAR: proofread and assisted data analysis, MAM: assisted in supervision of the clinical part and writing, AH: supervised and got the fund for whole project and assisted data collection, analysis and proofreading. All authors have read and approved the manuscript.

Ethics approval and consent to participate

Ethical approval was obtained from the Universiti Sains Malaysia Research Ethics Committee (Human) (USM/JEPeM/15110495) and data were analyzed anonymously. No consent, written or verbal, was not required.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
Department of Medical Laboratory Sciences, Faculty of Allied Health Sciences, The Hashemite University, Zarqa, Jordan
(2)
Department of Medical Microbiology and Parasitology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia
(3)
Department of Orthopedic, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia

References

  1. Currie BJ. Melioidosis: evolving concepts in epidemiology, pathogenesis, and treatment. Semin Respir Crit Care Med. 2015;36(6):111–25.PubMedGoogle Scholar
  2. Cheng AC, Godoy D, Mayo M, Gal D, Spratt BG, Currie BJ. Isolates of Burkholderia pseudomallei from northern Australia are distinct by multilocus sequence typing, but strain types do not correlate with clinical presentation. J Clin Microbiol. 2004;42(12):5477–83.View ArticlePubMedPubMed CentralGoogle Scholar
  3. Currie BJ, Dance DA, Cheng AC. The global distribution of Burkholderia pseudomallei and melioidosis: an update. Trans R Soc Trop Med Hyg. 2008;102(1,1);1–4.Google Scholar
  4. Puthucheary SD. Melioidosis in Malaysia. Med J Malaysia. 2009;64(4):266–74.PubMedGoogle Scholar
  5. Currie BJ, Fisher DA, Howard DM, Burrow JN, Lo D, Selva-Nayagam S, Anstey NM, Huffam SE, Snelling PL, Marks PJ, Stephens DP, Lum GD, Jacups SP, Krause VL. Endemic melioidosis in tropical northern Australia: a 10-year prospective study and review of the literature. Clin Infect Dis. 2000;31(4,1): 981–986.Google Scholar
  6. White NJ. Melioidosis. Zentralbl Bakteriol. 1994;280:439–43.View ArticlePubMedGoogle Scholar
  7. Dance DAB. Melioidosis. In: Guerrant RL, Walker, D. H., Weller, P. F., editor. Tropical Infectious Diseases: principles, pathogens, & practice. 2 ed. Philadelphia: Elsevier/Churchill Livingston. 2004. p. 381–388.Google Scholar
  8. Sarovich DS, Price EP, Webb JR, Ward LM, Voutsinos MY, Tuanyok A, Mayo M, Kaestli M, Currie BJ. Variable Virulence Factors in Burkholderia pseudomallei (Melioidosis) Associated with Human Disease. PLoS ONE. 2014;9(3):e91682.View ArticlePubMedPubMed CentralGoogle Scholar
  9. Koonpaew S, Ubol MN, Sirisinha S, White NJ, Chaiyaroj SC. Genome fingerprinting by pulsed-field gel electrophoresis of isolates of Burkholderia pseudomallei from patients with melioidosis in Thailand. Acta Trop. 2000;74(2):187–91.View ArticlePubMedGoogle Scholar
  10. Azura MN, Norazah A, Kamel AG, Zorin SADNA. Fingerprinting of septicemic and localized Burkholderia pseudomallei isolates from Malaysian patients. Southeast Asian J Trop Med Public Health. 2011;42(1):114–21.PubMedGoogle Scholar
  11. Norton R, Roberts B, Freeman M, Wilson M, Ashhurst-Smith C, Lock W, Brookes D, La Brooy J. Characterisation and molecular typing of Burkholderia pseudomallei: are disease presentations of melioidosis clonally related? FEMS Immunol Med Microbiol. 1998;20(1):37–44.View ArticlePubMedGoogle Scholar
  12. Pitt TL, Trakulsomboon S, Dance DA. Molecular phylogeny of Burkholderia pseudomallei. Acta Trop. 2000;74(2):181–5.View ArticlePubMedGoogle Scholar
  13. Price EP, Sarovich DS, Viberg L, Mayo M, Kaestli M, Tuanyok A, Foster JT, Keim P, Pearson T, Currie BJ. Whole-genome sequencing of Burkholderia pseudomallei isolates from an unusual melioidosis case identifies a polyclonal infection with the same multilocus sequence type. J Clin Microbiol. 2015;53(1):282–6.View ArticlePubMedGoogle Scholar
  14. Maiden MC, Bygraves JA, Feil E, Morelli G, Russell JE, Urwin R, Zhang Q, Zhou J, Zurth K, Caugant DA, Feavers IM, Achtman M, Spratt BG. Multilocus sequence typing: a portable approach to the identification of clones within populations of pathogenic microorganisms. Proc Natl Acad Sci U S A. 1998;95(6):3140–5.View ArticlePubMedPubMed CentralGoogle Scholar
  15. Zueter AM, Rahman ZA, Yean CY, Harun A. Brief communication genotyping of Burkholderia pseudomallei revealed high genetic variability among isolates from a single population group. Int J Mol Epidemiol Genet. 2015;6(1):41–7.PubMedPubMed CentralGoogle Scholar
  16. Wuthiekanun V, Limmathurotsakul D, Chantratita N, Feil EJ, Day NP, Peacock SJ. Burkholderia Pseudomallei is genetically diverse in agricultural land in Northeast Thailand. PLoS Negl Trop Dis. 2009;3:e496.View ArticlePubMedPubMed CentralGoogle Scholar
  17. Inglis TJ, Garrow SC, Henderson M, Clair A, Sampson J, O'Reilly L, Cameron B. Burkholderia pseudomallei traced to water treatment plant in Australia. Emerg Infect Dis. 2000;6(1):56–9.PubMedPubMed CentralGoogle Scholar
  18. Maharjan B, Chantratita N, Vesaratchavest M, Cheng A, Wuthiekanun V, Chierakul W, Chaowagul W, Day NP, Peacock SJ. Recurrent melioidosis in patients in northeast Thailand is frequently due to reinfection rather than relapse. J Clin Microbiol. 2005;43(12):6032–4.View ArticlePubMedPubMed CentralGoogle Scholar
  19. Godoy D, Randle G, Simpson AJ, Aanensen DM, Pitt TL, Kinoshita R, Spratt BG. Multilocus sequence typing and evolutionary relationships among the causative agents of melioidosis and glanders, Burkholderia pseudomallei and Burkholderia mallei. J Clin Microbiol. 2003;41(5):2068–79.View ArticlePubMedPubMed CentralGoogle Scholar
  20. Tamura K, Stecher G, Peterson D, Filipski A, Kumar S. MEGA6: Molecular Evolutionary Genetics Analysis version 6.0. Mol Biol Evol 2013;30(12): 2725–2729.Google Scholar
  21. Feil EJ, Li BC, Aanensen DM, Hanage WP, Spratt BG. eBURST: inferring patterns of evolutionary descent among clusters of related bacterial genotypes from multilocus sequence typing data. J Bacteriol. 2004;186(5):1518–30.View ArticlePubMedPubMed CentralGoogle Scholar
  22. Spratt BG, Hanage WP, Li B, Aanensen DM, Feil EJ. Displaying the relatedness among isolates of bacterial species-the eBURST approach. FEMS Microbiol Lett. 2004;241(2):129–34.View ArticlePubMedGoogle Scholar
  23. Zueter A, Yean YC, Abumarzouq M, Abdul Rahman Z, Deris ZZ, Harun A. The epidemiology and clinical spectrum of melioidosis in a teaching hospital in a north-eastern state of Malaysia: a fifteen-year review. BMC Infect Dis. 2016;16:333.View ArticlePubMedPubMed CentralGoogle Scholar
  24. Butler D. Viral research faces clampdown. Nature. 2012;490:456.View ArticlePubMedGoogle Scholar
  25. Holden MT, Titball RW, Peacock SJ, Cerdeno-Tarraga AM, Atkins T, Crossman LC, Pitt T, Churcher C, Mungall K, Bentley SD, Sebaihia M, Thomson NR, Bason N, Beacham IR, Brooks K, Brown KA, Brown NF, Challis GL, Cherevach I, Chillingworth T, Cronin A, Crossett B, Davis P, DeShazer D, Feltwell T, Fraser A, Hance Z, Hauser H, Holroyd S, Jagels K, Keith KE, Maddison M, Moule S, Price C, Quail MA, Rabbinowitsch E, Rutherford K, Sanders M, Simmonds M, Songsivilai S, Stevens K, Tumapa S, Vesaratchavest M, Whitehead S, Yeats C, Barrell BG, Oyston PC, Parkhill J. Genomic plasticity of the causative agent of melioidosis, Burkholderia pseudomallei. Proc Natl Acad Sci USA. 2004;101(39): 14240–14245.Google Scholar
  26. Cheng AC, Day NP, Mayo MJ, Gal D, Currie BJ. Burkholderia pseudomallei strain type, based on pulsed-field gel electrophoresis, does not determine disease presentation in melioidosis. Microbes Infect. 2005;7(1):104–9.View ArticlePubMedGoogle Scholar
  27. Vadivelu J, Puthucheary SD, Mifsud A, Drasar BS, Dance DA, Pitt TI. Ribotyping and DNA macrorestriction analysis of isolates of Burkholderia pseudomallei from cases of melioidosis in Malaysia. Trans R Soc Trop Med Hyg. 1997;91(3):358–60.View ArticlePubMedGoogle Scholar
  28. Radua S, Ling OW, Srimontree S, Lulitanond A, Hin WF, Yuherman LS, Rusul G, Mutalib AR. Characterization of Burkholderia pseudomallei isolated in Thailand and Malaysia. Diagn Microbiol Infect Dis. 2000;38(3):141–5.View ArticlePubMedGoogle Scholar
  29. Chua KH, See KH, Thong KL, Puthucheary SDDNA. Fingerprinting of human isolates of Burkholderia pseudomallei from different geographical regions of Malaysia. Trop Biomed. 2010;27(3):517–24.PubMedGoogle Scholar
  30. Leelayuwat C, Romphruk A, Lulitanond A, Trakulsomboon S, Thamlikitkul V. Genotype analysis of Burkholderia pseudomallei using randomly amplified polymorphic DNA (RAPD): indicative of genetic differences amongst environmental and clinical isolates. Acta Trop. 2000;77(2):229–37.View ArticlePubMedGoogle Scholar
  31. Mukhopadhyay C, Kaestli M, Vandana KE, Sushma K, Mayo M, Richardson L, Tuanyok A, Keim P, Godoy D, Spratt BG, Currie BJ. Molecular characterization of clinical Burkholderia pseudomallei isolates from India. Am J Trop Med Hyg. 2011;85(1):121–3.View ArticlePubMedPubMed CentralGoogle Scholar
  32. Cheng AC, Ward L, Godoy D, Norton R, Mayo M, Gal D, Spratt BG, Currie BJ. Genetic diversity of Burkholderia pseudomallei isolates in Australia. J Clin Microbiol. 2008;46(1):249–54.View ArticlePubMedGoogle Scholar
  33. McCombie RL, Finkelstein RA, Woods DE. Multilocus sequence typing of historical Burkholderia pseudomallei isolates collected in Southeast Asia from 1964 to 1967 provides insight into the epidemiology of melioidosis. J Clin Microbiol. 2006;44(8):2951–62.View ArticlePubMedPubMed CentralGoogle Scholar
  34. Currie B, Smith-Vaughan H, Golledge C, Buller N, Sriprakash KS, Kemp DJ. Pseudomonas pseudomallei isolates collected over 25 years from a non-tropical endemic focus show clonality on the basis of ribotyping. Epidemiol Infect. 1994;113(2):307–12.View ArticlePubMedPubMed CentralGoogle Scholar
  35. Inglis TJ, Garrow SC, Adams C, Henderson M, Mayo M, Currie BJ. Acute melioidosis outbreak in Western Australia. Epidemiol Infect. 1999;123(3):437–43.View ArticlePubMedPubMed CentralGoogle Scholar
  36. Liu Y, Loh JP, Aw LT, Yap EP, Lee MA, Ooi EE. Rapid molecular typing of Burkholderia pseudomallei, isolated in an outbreak of melioidosis in Singapore in 2004, based on variable-number tandem repeats. Trans R Soc Trop Med Hyg. 2006;100(7):687–92.View ArticlePubMedGoogle Scholar
  37. Currie BJ, Haslem A, Pearson T, Hornstra H, Leadem B, Mayo M, Gal D, Ward L, Godoy D, Spratt BG, Keim P. Identification of melioidosis outbreak by multilocus variable number tandem repeat analysis. Emerg Infect Dis. 2009;15(2):169–74.View ArticlePubMedPubMed CentralGoogle Scholar
  38. McRobb E, Sarovich DS, Price EP, Kaestli M, Mayo M, Keim P, Currie BJ. Tracing melioidosis back to the source: using whole-genome sequencing to investigate an outbreak originating from a contaminated domestic water supply. J Clin Microbiol. 2015;53(4):1144–8.View ArticlePubMedPubMed CentralGoogle Scholar
  39. Spratt BG, Hanage WP, Feil EJ. The relative contributions of recombination and point mutation to the diversification of bacterial clones. Curr OpinMicrobiol. 2001;4(5):602–6.Google Scholar
  40. De Smet B, Sarovich DS, Price EP, Mayo M, Theobald V, Kham C, Heng S, Thong P, Holden MT, Parkhill J, Peacock SJ, Spratt BG, Jacobs JA, Vandamme P, Currie BJ. Whole-genome sequencing confirms that Burkholderia pseudomallei multilocus sequence types common to both Cambodia and Australia are due to homoplasy. J Clin Microbiol. 2015;53(1):323–6.View ArticlePubMedGoogle Scholar
  41. Chen H, Xia L, Zhu X, Li W, Du X, Wu D, Hai R, Shen X, Liang Y, Cai H, Zheng X. Burkholderia pseudomallei sequence type 562 in China and Australia. Emerg Infect Dis. 2015;21(1):166–8.View ArticlePubMedPubMed CentralGoogle Scholar

Copyright

© The Author(s). 2017

Advertisement