Burkholderia pseudomallei is a Gram-negative bacterium that causes melioidosis. Melioidosis is a potentially fatal disease that is endemic in Southeast Asia and Northern Australia and is being increasingly recognized in other regions worldwide. Melioidosis can affect any organ system and present with a wide range of clinical manifestations including pneumonia, bone, skin/soft tissue, or central nervous system infections. In this report, we describe a diabetic farmer who succumbed to persistent B. pseudomallei bacteraemia with multiorgan involvement despite treatment with meropenem and ceftazidime.
A 12-year-old boy was admitted after 11 days of fever and 2 days of nasal obstruction as well as swelling of a right cervical lymph node. Nasal endoscopy and computed tomography of the neck showed a nasopharyngeal mass occupying the entire nasopharynx, extending into the nasal cavity, and obliterating the fossa of Rosenmuller. Abdominal ultrasonography revealed a small solitary splenic abscess. Although a nasopharyngeal tumor or malignancy was initially considered, biopsy of the mass showed only suppurative granulomatous inflammation, and bacterial culture from the enlarged cervical lymph node yielded Burkholderia pseudomallei. The symptoms, nasopharyngeal mass, and cervical lymph node enlargement resolved with melioidosis-directed antibiotic therapy. Although rarely reported, the nasopharynx may be an important primary site of infection in melioidosis patients, especially in pediatric patients.
Burkholderia pseudomallei primary diagnostic cultures demonstrate colony morphology variation associated with expression of virulence and adaptation proteins. This study aims to examine the ability of B. pseudomallei colony variants (wild type [WT] and small colony variant [SCV]) to survive and replicate intracellularly in A549 cells and to identify the alterations in the protein expression of these variants, post-exposure to the A549 cells. Intracellular survival and cytotoxicity assays were performed followed by proteomics analysis using two-dimensional gel electrophoresis. B. pseudomallei SCV survive longer than the WT. During post-exposure, among 259 and 260 protein spots of SCV and WT, respectively, 19 were differentially expressed. Among SCV post-exposure up-regulated proteins, glyceraldehyde 3-phosphate dehydrogenase, fructose-bisphosphate aldolase (CbbA) and betaine aldehyde dehydrogenase were associated with adhesion and virulence. Among the down-regulated proteins, enolase (Eno) is implicated in adhesion and virulence. Additionally, post-exposure expression profiles of both variants were compared with pre-exposure. In WT pre- vs post-exposure, 36 proteins were differentially expressed. Of the up-regulated proteins, translocator protein, Eno, nucleoside diphosphate kinase (Ndk), ferritin Dps-family DNA binding protein and peptidyl-prolyl cis-trans isomerase B were implicated in invasion and virulence. In SCV pre- vs post-exposure, 27 proteins were differentially expressed. Among the up-regulated proteins, flagellin, Eno, CbbA, Ndk and phenylacetate-coenzyme A ligase have similarly been implicated in adhesion, invasion. Protein profiles differences post-exposure provide insights into association between morphotypic and phenotypic characteristics of colony variants, strengthening the role of B. pseudomallei morphotypes in pathogenesis of melioidosis.
Melioidosis and leptospirosis, caused by two different bacteria, Burkholderia pseudomallei and Leptospira spp., are potentially fatal infections that share a very similar spectrum of clinical features and cause significant mortality and morbidity in humans and livestock. Early detection is important for better clinical consequences. To our knowledge, there is no diagnostic tool available to simultaneously detect and differentiate melioidosis and leptospirosis in humans and animals. In this study, we described a duplex TaqMan probe-based qPCR for the detection of B. pseudomallei and Leptospira spp. DNA. The performance of the assay was evaluated on 20 B. pseudomallei isolates, 23 Leptospira strains, and 39 other microorganisms, as well as two sets of serially diluted reference strains. The duplex qPCR assay was able to detect 0.02 pg (~ 4 copies) Leptospira spp. DNA and 0.2 pg (~ 25.6 copies) B. pseudomallei DNA. No undesired amplification was observed in other microorganisms. In conclusion, the duplex qPCR assay was sensitive and specific for the detection of B. pseudomallei & Leptospira spp. DNA and is suitable for further analytical and clinical evaluation.
We report the draft genome sequences of two antimicrobial-producing isolates, Burkholderia sp. strains MSh1 and MSh2, which were isolated from tropical peat swamp forest soil. Putative genes related to different antimicrobial production have been annotated in both genome sequences.
Bacteria realize the ability to communicate by production of quorum sensing (QS) molecules called autoinducers, which regulate the physiological activities in their ecological niches. The oral cavity could be a potential area for the presence of QS bacteria. In this study, we report the isolation of a QS bacterial isolate C10B from dentine caries. Preliminary screening using Chromobacterium violaceum CV026 biosensor showed that isolate C10B was able to produce N-acylhomoserine lactones (AHLs). This bacterium was further identified as a member of Burkholderia, an opportunistic pathogen. The isolated Burkholderia sp. was confirmed to produce N-hexanoyl-L-homoserine lactone (C6-HSL), N-octanoyl-L-homoserine lactone (C8-HSL), N-decanoyl-L-homoserine lactone (C10-HSL) and N-dodecanoyl-L-homoserine lactone (C12-HSL).
The search for novel immunogenic polypeptides to improve the accuracy and reliability of serologic diagnostic methods for Burkholderia pseudomallei infection is ongoing. We employed a rapid and efficient approach to identify such polypeptides with sera from melioidosis patients using a small insert genomic expression library created from clinically confirmed local virulent isolates of B. pseudomallei. After 2 rounds of immunoscreening, 6 sero-positive clones expressing immunogenic peptides were sequenced and their identities were: benzoate 1,2-dioxygenase beta subunit, a putative 200 kDa antigen p200, phosphotransferase enzyme family protein, short chain dehydrogenase and 2 hypothetical proteins. These immunogens were then transferred to an ELISA platform for further large scale screening. By combining shotgun expression library and ELISA assays, we identified 2 polypeptides BPSS1904 (benzoate 1,2-dioxygenase beta subunit) and BPSL3130 (hypothetical protein), which had sensitivities of 78.9% and 79.4% and specificities of 88.1% and 94.8%, respectively in ELISA test, thus suggesting that both are potential candidate antigens for the serodiagnosis of infections caused by B. pseudomallei.
Burkholderia pseudomallei is a facultative intracellular pathogen of phagocytic and non-phagocytic cells. How the bacterium interacts with host macrophage cells is still not well understood and is critical to appreciate the strategies used by this bacterium to survive and how intracellular survival leads to disease manifestation.
Melioidosis is an infection caused by Gram negative bacterium Burkholderia pseudomallei leading to abscesses in lungs, liver, spleen, musculoskeletal system, prostate and sepsis. We present a rare case of purulent pericardial effusion caused by melioidosis with concomitant pneumonia and splenic abscesses. The patient underwent pericardiocentesis and successfully recovered from cardiogenic and septic shock.
An outbreak of Burkholderia cepacia septicaemia occurred in our neonatal unit over a 9-week period in 2001, affecting 23 babies and two died. A second outbreak lasting 8 days occurred a year later, affecting five babies.
A previously healthy Chinese male working in Malaysia returned to China with high fever. A blood culture showed Burkholderia pseudomallei strain WCBP1. This isolate was sequenced, showing type, ST881, which appears to be present in Malaysia. WCP1 had unusual susceptibility to aminoglycosides and habored the Yersinia-like fimbrial gene cluster for virulence. The patient's condition deteriorated rapidly but he recovered after receiving meropenem and intensive care support. Melioidosis is a potential problem among Chinese imigrant workers with strains new to China being identified.
Epidemiology of melioidosis is poorly understood because its occurrence is influenced by complex interaction of environmental, climatic, physicochemical and host factors. We investigated the potential risk factors for the exposure to Burkholderia pseudomallei in small ruminants' farms in Peninsular Malaysia.
Burkholderia sp. strain USMB20 is a plant growth-promoting rhizobacterium that was isolated from nodules of the leguminous cover crop Mucuna bracteata. The draft genome sequence of Burkholderia sp. strain USMB20 has an assembly size of 7.7 Mbp in 26 contigs with a GC content of 66.88%.
Burkholderia pseudomallei the causative agent of melioidosis, is being increasingly recognized as an important cause of morbidity and mortality in South East Asia. Biofilm formation of B. pseudomallei may be responsible for dormancy, latency and relapse of melioidosis. Based on the colonial morphology of the bacteria on B. pseudomallei selective agar medium, seven distinct morphotypes were identified. This study was conducted to assess the in vitro biofilm produced by B. pseudomallei and to investigate possible correlation between B. pseudomallei morphotypes with biofilm forming abilities of the isolates. Using a standard biofilm crystal violet staining assay, comparison was made between the biofilm forming ability of 76 isolates of B. pseudomallei and Burkholderia thailandensis ATCC 700388. Amongst the blood isolates, 30.2% were considered as high biofilm producers and 27.9% were low producers, 33.3% of the pus isolates were considered as high and 16% low biofilm producers. Most of the isolates were identified as morphotype group 1 which displayed a rough centre with irregular circumference on the agar medium. However, we did not find any correlation of B. pseudomallei morphotypes with biofilm forming abilities (p > 0.05). Additional studies are needed to identify internal and external factors which contribute to the high and low biofilm formation of B. pseudomallei.
Melioidosis is an infectious disease caused by Burkholderia pseudomallei and endemic in Southeast Asia. One hundred and forty six clinical isolates of B. pseudomallei from different states in Malaysia were obtained and molecular typing was carried out using pulsed-field gel electrophoresis (PFGE). Overall, nine clusters were successfully identified. Burkholderia pseudomallei isolates used in this study were found to be genetically diverse and there were differences in the clusters of isolates from peninsular and east Malaysia. BS9 cluster was the most common cluster and found in all the states while BS2 cluster only existed in a particular state. Based on the PFGE analysis, the distribution of different B. pseudomallei clinical isolates in Malaysia was mapped.
Burkholderia sp. strain CCA53 was isolated from leaf soil collected in Higashi-Hiroshima City in Hiroshima Prefecture, Japan. Here, we present a draft genome sequence of this strain, which consists of a total of 4 contigs containing 6,647,893 bp, with a G+C content of 67.0% and comprising 9,329 predicted coding sequences.
The growth of microorganism on substrates, whether toxic or not usually exhibits sigmoidal
pattern. This sigmoidal growth pattern can be modelled using primary models such as Logistic,
modified Gompertz, Richards, Schnute, Baranyi-Roberts, Von Bertalanffy, Buchanan threephase
and Huang. Previously, the modified Gompertz model was chosen to model the growth of
Burkholderia sp. strain Neni-11 on acrylamide, which shows a sigmoidal curve. The modified
Gompertz model relies on the ordinary least squares method, which in turn relies heavily on
several important assumptions, which include that the data does not show autocorrelation. In this
work we perform statistical diagnosis test to test for the presence of autocorrelation using the
Durbin-Watson test and found that the model was adequate and robust as no autocorrelation of
the data was found.
In this study, a novel glyphosate-degrading shows the ability to reduce molybdenum to
molybdenum blue. The enzyme from this bacterium was partially purified and partially
characterized to ascertain whether the Mo-reducing enzyme from this bacterium shows better or
lower efficiency in reducing molybdenum compared to other Mo-reducing bacterium that only
exhibits a single biotransformation activity. The enzyme was partially purified using ammonium
sulphate fractionation. The Vmax for the electron donating substrate or NADH was at 1.905 nmole
Mo blue/min while the Km was 6.146 mM. The regression coefficient was 0.98. Comparative
assessment with the previously characterized Mo-reducing enzyme from various bacteria showed
that the Mo-reducing enzyme from Burkholderia vietnamiensis strain AQ5-12 showed a lower
enzyme activity.
Bahagian aktif bagi enzim toksin bakteria daripada Burkholderia pseudomallei, Pseudomonas aeruginosa dan difteria merupakan domain ADP-ribosilasi. Domain ini didapati terpelihara di antara ketiga-tiga mikroorganisme. Di dalam kajian ini, domain ADP-ribosilasi Burkholderia pseudomallei telah diamplifikasi daripada genom B. pseudomallei virulen dengan menggunakan pencetus-pencetus yang dibina berdasarkan kepada jujukan domain ADP ribosilasi Pseudomonas aeruginosa. Hasil DNA amplifikasi ditulenkan dan digunakan sebagai prob (HPCR2) untuk menyaring DNA selitan daripada B. pseudomallei yang diklonkan ke dalam vektor pengekspresan pSport-I. Objektif kajian ini adalah untuk menyaring lapan klon yang positif hasil daripada penyaringan awal melalui pendekatan immunoblot menggunakan antitoksin daripada arnab. Penyaringan ini juga melibatkan tiga klon yang tidak memberikan isyarat positif semasa penyaringan secara immunoblot. Keputusan menunjukkan hanya satu klon (L31) daripada lapan klon immunoblot positif mempunyai domain ADP-ribosilasi. Penjujukan DNA separa klon L31 secara manual melibatkan dua pencetus menghasilkan jujukan sepanjang 450pb. Analisis selanjutnya mendapati daripada enam kemungkinan translasi kepada polipeptida hanya satu polipeptida wujud yang tidak mempunyai sebarang kodon penamat pada jujukan kodonnya.
Burkholderia pseudomallei is an opportunistic pathogen and the causative agent of melioidosis. It is able to adapt to harsh environments and can live intracellularly in its infected hosts. In this study, identification of transcriptional factors that associate with the β' subunit (RpoC) of RNA polymerase was performed. The N-terminal region of this subunit is known to trigger promoter melting when associated with a sigma factor. A pull-down assay using histidine-tagged B. pseudomallei RpoC N-terminal region as bait showed that a hypothetical protein BPSS1356 was one of the proteins bound. This hypothetical protein is conserved in all B. pseudomallei strains and present only in the Burkholderia genus. A BPSS1356 deletion mutant was generated to investigate its biological function. The mutant strain exhibited reduced biofilm formation and a lower cell density during the stationary phase of growth in LB medium. Electron microscopic analysis revealed that the ΔBPSS1356 mutant cells had a shrunken cytoplasm indicative of cell plasmolysis and a rougher surface when compared to the wild type. An RNA microarray result showed that a total of 63 genes were transcriptionally affected by the BPSS1356 deletion with fold change values of higher than 4. The expression of a group of genes encoding membrane located transporters was concurrently down-regulated in ΔBPSS1356 mutant. Amongst the affected genes, the putative ion transportation genes were the most severely suppressed. Deprivation of BPSS1356 also down-regulated the transcriptions of genes for the arginine deiminase system, glycerol metabolism, type III secretion system cluster 2, cytochrome bd oxidase and arsenic resistance. It is therefore obvious that BPSS1356 plays a multiple regulatory roles on many genes.