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Genomics Jan 2020Differences in expression of potential virulence and survival genes were associated with B. pseudomallei colony morphology variants. Microarray was used to investigate...
Differences in expression of potential virulence and survival genes were associated with B. pseudomallei colony morphology variants. Microarray was used to investigate B. pseudomallei transcriptome alterations among the wild type and small colony variant (SCV) pre- and post-exposed to A549 cells. SCV pre- and post-exposed have lower metabolic requirements and consume lesser energy than the wild type pre- and post-exposed to A549. However, both the wild type and SCV limit their metabolic activities post- infection of A549 cells and this is indicated by the down-regulation of genes implicated in the metabolism of amino acids, carbohydrate, lipid, and other amino acids. Many well-known virulence and survival factors, including T3SS, fimbriae, capsular polysaccharides and stress response were up-regulated in both the wild type and SCV pre- and post-exposed to A549 cells. Microarray analysis demonstrated essential differences in bacterial response associated with virulence and survival pre- and post-exposed to A549 cells.
Topics: A549 Cells; Apoptosis; Burkholderia pseudomallei; Drug Resistance, Bacterial; Gene Expression Profiling; Humans; Microbial Viability; RNA, Bacterial; Stress, Physiological; Virulence; Virulence Factors
PubMed: 30980902
DOI: 10.1016/j.ygeno.2019.04.002 -
PLoS Neglected Tropical Diseases Sep 2016Accurate identification of pathogens with biowarfare importance requires detection tools that specifically differentiate them from near-neighbor species. Burkholderia...
Accurate identification of pathogens with biowarfare importance requires detection tools that specifically differentiate them from near-neighbor species. Burkholderia pseudomallei, the causative agent of a fatal disease melioidosis, is one such biothreat agent whose differentiation from its near-neighbor species is always a challenge. This is because of its phenotypic similarity with other Burkholderia species which have a wide spread geographical distribution with shared environmental niches. Melioidosis is a major public health concern in endemic regions including Southeast Asia and northern Australia. In India, the disease is still considered to be emerging. Prevalence surveys of this saprophytic bacterium in environment are under-reported in the country. A major challenge in this case is the specific identification and differentiation of B. pseudomallei from the growing list of species of Burkholderia genus. The objectives of this study included examining the prevalence of B. pseudomallei and near-neighbor species in coastal region of South India and development of a novel detection tool for specific identification and differentiation of Burkholderia species. Briefly, we analyzed soil and water samples collected from Malabar coastal region of Kerala, South India for prevalence of B. pseudomallei. The presumptive Burkholderia isolates were identified using recA PCR assay. The recA PCR assay identified 22 of the total 40 presumptive isolates as Burkholderia strains (22.72% and 77.27% B. pseudomallei and non-pseudomallei Burkholderia respectively). In order to identify each isolate screened, we performed recA and 16S rDNA sequencing. This two genes sequencing revealed that the presumptive isolates included B. pseudomallei, non-pseudomallei Burkholderia as well as non-Burkholderia strains. Furthermore, a gene termed D-beta hydroxybutyrate dehydrogenase (bdha) was studied both in silico and in vitro for accurate detection of Burkholderia genus. The optimized bdha based PCR assay when evaluated on the Burkholderia isolates of this study, it was found to be highly specific (100%) in its detection feature and a clear detection sensitivity of 10 pg/μl of purified gDNA was recorded. Nucleotide sequence variations of bdha among interspecies, as per in silico analysis, ranged from 8 to 29% within the target stretch of 730 bp highlighting the potential utility of bdha sequencing method in specific detection of Burkholderia species. Further, sequencing of the 730 bp bdha PCR amplicon of each Burkholderia strain isolated could differentiate the species and the data was comparable with recA sequence data of the strains. All sequencing results obtained were submitted to NCBI database. Bayesian phylogenetic analysis of bdha in comparison with recA and 16S rDNA showed that the bdha gene provided comparable identification of Burkholderia species.
Topics: Bacterial Typing Techniques; Bayes Theorem; Burkholderia pseudomallei; Humans; India; Melioidosis; Phylogeny; Prevalence; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Soil Microbiology; Water Microbiology
PubMed: 27632353
DOI: 10.1371/journal.pntd.0004956 -
MBio Sep 2013The Gram-negative bacterium Burkholderia pseudomallei is the causative agent of melioidosis, a serious infectious disease of humans and animals. Once considered an...
The Gram-negative bacterium Burkholderia pseudomallei is the causative agent of melioidosis, a serious infectious disease of humans and animals. Once considered an esoteric tropical disease confined to Southeast Asia and northern Australia, research on B. pseudomallei has recently gained global prominence due to its classification as a potential bioterrorism agent by countries such as the United States and also by increasing numbers of case reports from regions where it is not endemic. An environmental bacterium typically found in soil and water, assessing the true global prevalence of melioidosis is challenged by the fact that clinical symptoms associated with B. pseudomallei infection are extremely varied and may be confused with diverse conditions such as lung cancer, tuberculosis, or Staphyloccocus aureus infection. These diagnostic challenges, coupled with lack of awareness among clinicians, have likely contributed to underdiagnosis and the high mortality rate of melioidosis, as initial treatment is often either inappropriate or delayed. Even after antibiotic treatment, relapses are frequent, and after resolution of acute symptoms, chronic melioidosis can also occur, and the symptoms can persist for months to years. In a recent article, Price et al. [mBio 4(4):e00388-13, 2013, doi:10.1128/mBio.00388-13] demonstrate how comparative genomic sequencing can reveal the repertoire of genetic changes incurred by B. pseudomallei during chronic human infection. Their results have significant clinical ramifications and highlight B. pseudomallei's ability to survive in a wide range of potential niches within hosts, through the acquisition of genetic adaptations that optimize fitness and resource utilization.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Burkholderia pseudomallei; Chronic Disease; Humans; Melioidosis; Microbial Viability
PubMed: 24065633
DOI: 10.1128/mBio.00709-13 -
Journal of Bacteriology Jul 2011Glycosylation of proteins is known to impart novel physical properties and biological roles to proteins from both eukaryotes and prokaryotes. In this study, gel-based... (Comparative Study)
Comparative Study
Glycosylation of proteins is known to impart novel physical properties and biological roles to proteins from both eukaryotes and prokaryotes. In this study, gel-based glycoproteomics were used to identify glycoproteins of the potential biothreat agent Burkholderia pseudomallei and the closely related but nonpathogenic B. thailandensis. Top-down and bottom-up mass spectrometry (MS) analyses identified that the flagellin proteins of both species were posttranslationally modified by novel glycans. Analysis of proteins from two strains of each species demonstrated that B. pseudomallei flagellin proteins were modified with a glycan with a mass of 291 Da, while B. thailandensis flagellin protein was modified with related glycans with a mass of 300 or 342 Da. Structural characterization of the B. thailandensis carbohydrate moiety suggests that it is an acetylated hexuronic acid. In addition, we have identified through mutagenesis a gene from the lipopolysaccharide (LPS) O-antigen biosynthetic cluster which is involved in flagellar glycosylation, and inactivation of this gene eliminates flagellar glycosylation and motility in B. pseudomallei. This is the first report to conclusively demonstrate the presence of a carbohydrate covalently linked to a protein in B. pseudomallei and B. thailandensis, and it suggests new avenues to explore in order to examine the marked differences in virulence between these two species.
Topics: Amino Acid Sequence; Burkholderia; Burkholderia pseudomallei; Flagellin; Glycosylation; Mass Spectrometry; Molecular Sequence Data; Molecular Weight; Peptide Mapping
PubMed: 21602339
DOI: 10.1128/JB.01385-10 -
Tropical Biomedicine Jun 2015Burkholderia pseudomallei is the causative agent of melioidosis, which can form biofilms and microcolonies in vivo and in vitro. One of the hallmark characteristics of...
Burkholderia pseudomallei is the causative agent of melioidosis, which can form biofilms and microcolonies in vivo and in vitro. One of the hallmark characteristics of the biofilm-forming bacteria is that they can be up to 1,000 times more resistant to antibiotics than their free-living counterpart. Bacteria also become highly tolerant to antibiotics when nutrients are limited. One of the most important causes of starvation induced tolerance in vivo is biofilm growth. However, the effect of nutritional stress on biofilm formation and drug tolerance of B. pseudomallei has never been reported. Therefore, this study aims to determine the effect of nutrient-limited and enriched conditions on drug susceptibility of B. pseudomallei in both planktonic and biofilm forms in vitro using broth microdilution method and Calgary biofilm device, respectively. The biofilm formation of B. pseudomallei in nutrient-limited and enriched conditions was also evaluated by a modified microtiter-plate test. Six isolates of ceftazidime (CAZ)-susceptible and four isolates of CAZ-resistant B. pseudomallei were used. The results showed that the minimum bactericidal concentrations of CAZ against B. pseudomallei in nutrient-limited condition were higher than those in enriched condition. The drug susceptibilities of B. pseudomallei biofilm in both enriched and nutrient-limited conditions were more tolerant than those of planktonic cells. Moreover, the quantification of biofilm formation by B. pseudomallei in nutrient-limited condition was significantly higher than that in enriched condition. These data indicate that nutrient-limited condition could induce biofilm formation and drug tolerance of B. pseudomallei.
Topics: Anti-Bacterial Agents; Biofilms; Burkholderia pseudomallei; Culture Media; Drug Tolerance; Microbial Sensitivity Tests; Microbial Viability
PubMed: 26691259
DOI: No ID Found -
The American Journal of Tropical... Oct 2019is a selective agent that causes septic melioidosis and exhibits a broad range of lethal doses in animals. Host cellular virulence and phagocytic resistance are...
is a selective agent that causes septic melioidosis and exhibits a broad range of lethal doses in animals. Host cellular virulence and phagocytic resistance are pathologic keys of . We first proposed as the host cellular virulence model to mimic bacterial virulence against mammals and second established the resistance of to predation by as the phagocytosis model. The saprophytic sepsis-causing sp. (, , , and ) exhibited different virulence patterns in both simple models, but was the most toxic. Using both models, attenuated isolates of were selected from a transposon-mutant library and a panel of environmental isolates and reconfirmed by in vitro mouse peritoneal exudate cell association and invasion assays. The distinct pathological patterns of melioidosis were inducted by different selected isolates. Fatal melioidosis was induced by the isolates with high virulence in both simple models within 4-5 day, whereas the low-virulence isolates resulted in prolonged survival greater than 30 day. Infection with the isolates having high resistance to predation but a low killing effect led to 83% of mice with neurologic melioidosis. By contrast, infection with the isolates having low resistance to predation but high killing effect led to 20% cases with inflammation in the salivary glands. Our results indicated that individual isolates selected from simple biological models contribute differently to disease progression and/or tissue tropism.
Topics: Animals; Burkholderia pseudomallei; Caenorhabditis elegans; Dictyostelium; Female; Humans; Melioidosis; Mice; Mice, Inbred BALB C; Mutation; Virulence
PubMed: 31392941
DOI: 10.4269/ajtmh.19-0052 -
PLoS Neglected Tropical Diseases Jan 2016Melioidosis, caused by Burkholderia pseudomallei, is an endemic disease in Bangladesh. No systematic study has yet been done to detect the environmental source of the...
BACKGROUND
Melioidosis, caused by Burkholderia pseudomallei, is an endemic disease in Bangladesh. No systematic study has yet been done to detect the environmental source of the organism and its true extent in Bangladesh. The present study attempted to isolate B. pseudomallei in soil samples and to determine its seroprevalence in several districts in Bangladesh.
METHODOLOGY AND RESULTS
Soil samples were collected from rural areas of four districts of Bangladesh from where culture confirmed melioidosis cases were detected earlier. Multiple soil samples, collected from 5-7 sampling points of 3-5 sites of each district, were cultured in Ashdown selective media. Suspected colonies of B. pseudomallei were identified by biochemical and serological test, and by polymerase chain reaction (PCR) using 16s rRNA specific primers. Blood samples were collected from 940 healthy individuals of four districts to determine anti- B. pseudomallei IgG antibody levels by indirect enzyme linked immunosorbent assay (ELISA) using sonicated crude antigen. Out of 179 soil samples, B. pseudomallei was isolated from two samples of Gazipur district which is located 58 km north of capital Dhaka city. Both the isolates were phenotypically identical, arabinose negative and showed specific 550bp band in PCR. Out of 940 blood samples, anti- B. pseudomallei IgG antibody, higher than the cut-off value (>0.8), was detected in 21.5% individuals. Seropositivity rate was 22.6%-30.8% in three districts from where melioidosis cases were detected earlier, compared to 9.8% in a district where no melioidosis case was either detected or reported (p<0.01). Seropositivity increased with the advancement of age from 5.3% to 30.4% among individuals aged 1-10 years and > 50 years respectively. The seropositivity rates were 26.0% and 20.6% in male and female respectively, while it was 20-27% among different occupational groups. No significant association was observed with gender (χ2 = 3.441, p = 0.064) or any occupational group (χ2 = 3.835, p = 0.280).
CONCLUSION
This is the first study demonstrating the presence of B. pseudomallei in the environmental (soil) samples of Bangladesh. It also suggested that a large proportion of people, residing in these districts, were exposed to the organism.
Topics: Adolescent; Adult; Antibodies, Bacterial; Bangladesh; Burkholderia pseudomallei; Child; Child, Preschool; DNA Primers; Female; Humans; Male; Melioidosis; Middle Aged; Polymerase Chain Reaction; Seroepidemiologic Studies; Soil Microbiology; Young Adult
PubMed: 26771511
DOI: 10.1371/journal.pntd.0004301 -
Emerging Infectious Diseases Jul 2011
Topics: Animals; Burkholderia pseudomallei; History, 20th Century; Humans; Melioidosis; Terminology as Topic
PubMed: 21762621
DOI: 10.3201/eid1707.ET1707 -
Epidemiology and Infection Apr 1997Previous reports in the literature suggest that Burkholderia pseudomallei strains can be differentiated on the basis of animal virulence. Twenty environmentally and...
Previous reports in the literature suggest that Burkholderia pseudomallei strains can be differentiated on the basis of animal virulence. Twenty environmentally and clinically derived isolates of Burkholderia pseudomallei were examined for the production of exoenzymes, morphological and biochemical phenotypes and virulence for Syrian golden hamsters. The partial sequence of the 16S ribosomal RNA [rRNA] genes from a number of these strains was also determined. Based upon these observations, it is suggested that highly virulent Burkholderia pseudomallei strains are true Burkholderia pseudomallei strains. The DNA sequences of the 16S rRNA genes of the true Burkholderia pseudomallei strains were identical to the published sequences for Burkholderia pseudomallei while differences were revealed between the published sequences and those of the lowly virulent strains. Thus, these latter strains have been designated as Burkholderia pseudomallei-like organisms since they demonstrate significant differences in exoenzyme production, hamster virulence and 16S rRNA gene sequences.
Topics: Animals; Base Sequence; Biological Assay; Burkholderia pseudomallei; Cricetinae; Disease Models, Animal; Genotype; Humans; Lethal Dose 50; Mesocricetus; Molecular Sequence Data; Phenotype; RNA, Bacterial; RNA, Ribosomal, 16S; Serotyping
PubMed: 9129590
DOI: 10.1017/s095026889600739x -
PLoS Neglected Tropical Diseases Apr 2019Burkholderia pseudomallei is the causative agent of melioidosis, a severe infectious disease in tropical regions. It is necessary to understand the risk of acquiring...
BACKGROUND
Burkholderia pseudomallei is the causative agent of melioidosis, a severe infectious disease in tropical regions. It is necessary to understand the risk of acquiring this infection from the environment.
METHODOLOGY /PRINCIPAL FINDINGS
The prevalence, concentration and genetic diversity of B. pseudomallei isolates collected from two sites in Buriram, Northeast Thailand were investigated. Forty-four environmental samples (18 from soil, 14 from rice rhizosphere, and 12 from water) were collected; of those 44 samples, 19 were collected from near a patient's residence and 25 from suspected exposure sites and compared with 10 clinical isolates of the patient. Quantitative culture was performed, and B. pseudomallei was identified using the latex agglutination test and matrix-laser absorption ionisation mass spectrometry. Genotyping was performed in 162 colonies from clinical (N = 10) and environmental samples (N = 152) using pulse-field gel electrophoresis (PFGE) followed by multi-locus sequence typing (MLST) of the clinical strain. B. pseudomallei was detected in 11 of the 44 environmental samples (1 from soil, 4 from rice rhizosphere, and 6 from water). The bacterial count in the positive soil sample was 115 CFU/g. The mean concentrations ± SDs of B. pseudomallei in the positive water and rhizosphere samples were 5.1 ± 5.5 CFU/ml and 80 ± 49 CFU/g, respectively. Six water samples with positive results were collected from a pond and water sources for drinking and daily use. All colonies isolated from the patient shared the same PFGE type (PT) indicating monoclonal infection of ST99. Although the 152 colonies from environmental isolates exhibited 25 PTs, none were identical to the patient's isolates. PT5 and PT7 were most common genotype among the environmental samples.
CONCLUSIONS/SIGNIFICANCE
Diverse genotypes of B. pseudomallei were prevalent in the environment. However, the patient may have been infected with a low-density genotype. Intervention strategies for preventing B. pseudomallei infection are required.
Topics: Burkholderia pseudomallei; Environmental Monitoring; Genetic Variation; Genotype; Humans; Male; Melioidosis; Middle Aged; Multilocus Sequence Typing; Oryza; Prevalence; Soil Microbiology; Thailand; Water Microbiology
PubMed: 31002718
DOI: 10.1371/journal.pntd.0007348