scholarly journals Drug screening to identify compounds to act as co-therapies for the treatment of pathogenic Burkholderia

2019 ◽  
Author(s):  
Sam Barker ◽  
Sarah V. Harding ◽  
David Gray ◽  
Mark I. Richards ◽  
Helen S. Atkins ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Bacterial Species ◽  
Treatment Burden ◽  
Surrogate Optimization ◽  
Middle Income ◽  
Intravenous Treatment ◽  
Efficacious Treatment ◽  
Culturable Cell ◽  
The Tropics ◽  
High Throughput Assay

AbstractBurkholderia pseudomallei is a soil-dwelling organism present throughout the tropics, and is the causative agent of melioidosis, a disease that is believed to kill 89,000 people per year. It is naturally resistant to most currently available antibiotics. The most efficacious treatment for melioidosis requires at least two weeks of intravenous treatment with ceftazidime or meropenem. This places a large treatment burden on the predominantly middle income nations where the majority of disease occurs. We have established a high-throughput assay for compounds that could be used as a co-therapy to potentiate the effect of ceftazidime, using the related non-pathogenic bacterium Burkholderia thailandensis as a surrogate. Optimization of the assay gave a Z’ factor of 0.68. We screened a library of 61,250 compounds, and identified 29 compounds with a pIC50 (-log10(IC50)) greater than five. Detailed investigation allowed us to down select to six “best in class” compounds, which included the licensed drug chloroxine. Co-treatment of B. thailandensis with ceftazidime and chloroxine reduced culturable cell numbers by two orders of magnitude over 48 hours compared to treatment with ceftazidime alone. Hit expansion around chloroxine was performed using commercially available compounds. Minor modifications to the structure abolished activity, suggesting that chloroxine likely acts against a specific target. Finally, preliminary data also demonstrates the utility of chloroxine to act as a co-therapy to potentiate the effect of ceftazidime against B. pseudomallei. This approach successfully identified potential co-therapies for a recalcitrant Gram-negative bacterial species. Our assay could be used more widely to aid in chemotherapy against these bacteria.

scholarly journals Drug screening to identify compounds to act as co-therapies for the treatment of Burkholderia species

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0248119
Author(s):  
Sam Barker ◽  
Sarah V. Harding ◽  
David Gray ◽  
Mark I. Richards ◽  
Helen S. Atkins ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Bacterial Species ◽  
Initial Study ◽  
Treatment Burden ◽  
Surrogate Optimization ◽  
Middle Income ◽  
Intravenous Treatment ◽  
Culturable Cell ◽  
The Tropics ◽  
High Throughput Assay

Burkholderia pseudomallei is a soil-dwelling organism present throughout the tropics. It is the causative agent of melioidosis, a disease that is believed to kill 89,000 people per year. It is naturally resistant to many antibiotics, requiring at least two weeks of intravenous treatment with ceftazidime, imipenem or meropenem followed by 6 months of orally delivered co-trimoxazole. This places a large treatment burden on the predominantly middle-income nations where the majority of disease occurs. We have established a high-throughput assay for compounds that could be used as a co-therapy to potentiate the effect of ceftazidime, using the related non-pathogenic bacterium Burkholderia thailandensis as a surrogate. Optimization of the assay gave a Z’ factor of 0.68. We screened a library of 61,250 compounds and identified 29 compounds with a pIC50 (-log10(IC50)) greater than five. Detailed investigation allowed us to down select to six “best in class” compounds, which included the licensed drug chloroxine. Co-treatment of B. thailandensis with ceftazidime and chloroxine reduced culturable cell numbers by two orders of magnitude over 48 hours, compared to treatment with ceftazidime alone. Hit expansion around chloroxine was performed using commercially available compounds. Minor modifications to the structure abolished activity, suggesting that chloroxine likely acts against a specific target. Finally, an initial study demonstrates the utility of chloroxine to act as a co-therapy to potentiate the effect of ceftazidime against B. pseudomallei. This approach successfully identified potential co-therapies for a recalcitrant Gram-negative bacterial species. Our assay could be used more widely to aid in chemotherapy to treat infections caused by these bacteria.

scholarly journals Investigation of Melioidosis Outbreak in Pig Farms in Southern Thailand

2020 ◽  
Vol 7 (1) ◽  
pp. 9 ◽  
Author(s):  
Wiyada Kwanhian ◽  
Treenate Jiranantasak ◽  
Aleeza T. Kessler ◽  
Bryn E. Tolchinsky ◽  
Sarah Parker ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Contaminated Water ◽  
Environmental Investigation ◽  
Source Of Infection ◽  
Local Sequence ◽  
Southern Thailand ◽  
Life Threatening ◽  
The Tropics ◽  
Privately Owned ◽  
Sequence Types

Melioidosis, caused by the Gram-negative bacterium Burkholderia pseudomallei, is a potentially life-threatening infection that can affect humans and a wide variety of animals in the tropics. In December 2017, a swine melioidosis case was discovered during a meat inspection at a privately-owned slaughterhouse in Nakhon Si Thammarat Province in southern Thailand. The infection, which continued for several months, caused a dispute about where the disease began. An environmental investigation into two farms—both involved in raising the first infected pig—ensued. Through genetic analysis, the investigation revealed that a contaminated water supply at one farm was the probable source of infection. The three local sequence types identified in the investigation were types 51, 298 and 392.

scholarly journals 728. Genomic Characterization of Burkholderia pseudomallei Isolates in Colombia

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S463-S463
Author(s):  
Catalina Espitia-Acero ◽  
Rafael Rios ◽  
Monica Gabriela huertas ◽  
Sandra Vargas ◽  
Carolina Duarte Valderrama ◽  
...  
Keyword(s):  
Population Structure ◽  
Rural Areas ◽  
Burkholderia Pseudomallei ◽  
Virulence Determinants ◽  
Secretion Systems ◽  
Research Support ◽  
Middle Income ◽  
Resistance Determinants ◽  
Low Middle Income Countries ◽  
Genomic Characterization

Abstract Background Melioidosis is a serious infection caused by Burkholderia pseudomallei (Bps), an opportunistic organism, highly adaptable and with a wide array of intrinsic virulence factors and antimicrobial resistance determinants. Bps is underdiagnosed due to its slow growth on routine laboratory media and the lack of robust diagnostic infrastructure in rural areas of low/middle income countries. Recent data indicates that Bps infections are increasing in Colombia (COL). However, the understanding of the genomic epidemiology and population structure of the emerging Bps isolates in COL is unknown. Here we characterize the genomic features of Bps isolates from infected patients in COL. Methods We identified 13 Bps clinical isolates recovered in 5 Colombian cities between 2018 and 2020. We performed WGS and phylogenomic analyses using Bayesian methods. For comparisons, we included 82 publicly available genomes from Bps recovered worldwide (including 10 additional isolates from COL). Additionally, we characterized the resistome, virulome and MLST of all isolates. Results 12 out of the 13 isolates were confirmed as Bps and 1 belonged to the B. cepacia complex. The Bps population structure was divided in two main clades: clade 1 with isolates from Asia and Australia, and clade 2 with isolates from Africa, America, and the Caribbean (Figure 1). We found two groups of Colombian isolates, the first was related to ST518 and the second, highly diverse including 11 different STs (1742, 1748, 92, among others). Genomic characterization showed the presence of β-lactamases PenA (n=11) and OXA-57 (n=1). We also identified a T584A substitution in PBP3 (n=11). All genomes contained virulence determinants of motility (BimA), invasion (Flagella), signaling (CdpA) and adherence (Type IV pili). Type III and VI secretion systems, were also found in all isolates resembling Bps from other parts of the world. Figure 1. Maximum clade credibility tree of 82 genomes of Bps. The inner ring shows the ST for each genome, while the outer ring shows the geographical region associated with them. Groups highlighted in red show the location of the Colombian genomes and those related to them. Conclusion Bps is an emerging pathogen in COL and its population structure seems highly diverse, predominantly of the American lineage and absence of Australasians strains. A high prevalence ( >90%) of resistance determinants, particularly related to β-lactams, suggest that active surveillance of these emergent pathogens is needed in countries like COL. Disclosures Cesar A. Arias, M.D., MSc, Ph.D., FIDSA, Entasis Therapeutics (Grant/Research Support)MeMed Diagnostics (Grant/Research Support)Merk (Grant/Research Support) Lorena Diaz, PhD , Nothing to disclose

scholarly journals Groundwater Seeps Facilitate Exposure to Burkholderia pseudomallei

2011 ◽  
Vol 77 (20) ◽  
pp. 7243-7246 ◽  
Author(s):  
Anthony Baker ◽  
Donald Tahani ◽  
Christopher Gardiner ◽  
Keith L. Bristow ◽  
Andrew R. Greenhill ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Extreme Weather Events ◽  
Clinical Samples ◽  
Residential Areas ◽  
Content Type ◽  
Weather Events ◽  
Potential Reservoir ◽  
Site Access ◽  
The Tropics ◽  
Pcr Targeting

ABSTRACTBurkholderia pseudomalleiis a saprophytic bacterium which is the causative agent of melioidosis, a common cause of fatal bacterial pneumonia and sepsis in the tropics. The incidence of melioidosis is clustered spatially and temporally and is heavily linked to rainfall and extreme weather events. Clinical case clustering has recently been reported in Townsville, Australia, and has implicated Castle Hill, a granite monolith in the city center, as a potential reservoir of infection. Topsoil and water from seasonal groundwater seeps were collected around the base of Castle Hill and analyzed by quantitative real-time PCR targeting the type III secretion system genes for the presence ofB. pseudomallei. The organism was identified in 65% (95% confidence interval [CI], 49.5 to 80.4) of soil samples (n= 40) and 92.5% (95% CI, 83.9 to 100) of seasonal groundwater samples (n= 40). Further sampling of water collected from roads and gutters in nearby residential areas after an intense rainfall event found that 88.2% (95% CI, 72.9 to 100) of samples (n= 16) contained viableB. pseudomalleiat concentrations up to 113 CFU/ml. Comparison of isolates using multilocus sequence typing demonstrated clinical matches and close associations between environmental isolates and isolates derived from clinical samples from patients in Townsville. This study demonstrated that waterborneB. pseudomalleifrom groundwater seeps around Castle Hill may facilitate exposure toB. pseudomalleiand contribute to the clinical clustering at this site. Access to this type of information will advise the development and implementation of public health measures to reduce the incidence of melioidosis.

Burkholderia pseudomallei pathogenesis and survival in different niches

2020 ◽  
Vol 48 (2) ◽  
pp. 569-579
Author(s):  
Chee-Hoo Yip ◽  
Ahmad-Kamal Ghazali ◽  
Sheila Nathan
Keyword(s):  
Burkholderia Pseudomallei ◽  
Salt Water ◽  
Mortality Rates ◽  
Current Treatment ◽  
Water Bodies ◽  
Intracellular Pathogen ◽  
Stagnant Water ◽  
Wide Range ◽  
The Tropics ◽  
Highly Virulent

Burkholderia pseudomallei (Bp) is the causative agent of melioidosis, a disease of the tropics with high clinical mortality rates. To date, no vaccines are approved for melioidosis and current treatment relies on antibiotics. Conversely, common misdiagnosis and high pathogenicity of Bp hamper efforts to fight melioidosis. This bacterium can be isolated from a wide range of niches such as waterlogged fields, stagnant water bodies, salt water bodies and from human and animal clinical specimens. Although extensive studies have been undertaken to elucidate pathogenesis mechanisms of Bp, little is known about how a harmless soil bacterium adapts to different environmental conditions, in particular, the shift to a human host to become a highly virulent pathogen. The bacterium has a large genome encoding an armory of factors that assist the pathogen in surviving under stressful conditions and assuming its role as a deadly intracellular pathogen. This review presents an overview of what is currently known about how the pathogen adapts to different environments. With in-depth understanding of Bp adaptation and survival, more effective therapies for melioidosis can be developed by targeting related genes or proteins that play a major role in the bacteria's survival.

scholarly journals Role of RelA and SpoT in Burkholderia pseudomallei Virulence and Immunity

2012 ◽  
Vol 80 (9) ◽  
pp. 3247-3255 ◽  
Author(s):  
Claudia M. Müller ◽  
Laura Conejero ◽  
Natasha Spink ◽  
Matthew E. Wand ◽  
Gregory J. Bancroft ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Galleria Mellonella ◽  
Bacterial Species ◽  
Virulence Gene ◽  
Live Attenuated Vaccine ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Control And Prevention

ABSTRACTBurkholderia pseudomalleiis a Gram-negative soil bacterium and the causative agent of melioidosis, a disease of humans and animals. It is also listed as a category B bioterrorism threat agent by the U.S. Centers for Disease Control and Prevention, and there is currently no melioidosis vaccine available. Small modified nucleotides such as the hyperphosphorylated guanosine molecules ppGpp and pppGpp play an important role as signaling molecules in prokaryotes. They mediate a global stress response under starvation conditions and have been implicated in the regulation of virulence and survival factors in many bacterial species. In this study, we created arelA spoTdouble mutant inB. pseudomalleistrain K96243, which lacks (p)ppGpp-synthesizing enzymes, and investigated its phenotypein vitroandin vivo. TheB. pseudomalleiΔrelAΔspoTmutant displayed a defect in stationary-phase survival and intracellular replication in murine macrophages. Moreover, the mutant was attenuated in theGalleria mellonellainsect model and in both acute and chronic mouse models of melioidosis. Vaccination of mice with the ΔrelAΔspoTmutant resulted in partial protection against infection with wild-typeB. pseudomallei. In summary, (p)ppGpp signaling appears to represent an essential component of the regulatory network governing virulence gene expression and stress adaptation inB. pseudomallei, and the ΔrelAΔspoTmutant may be a promising live-attenuated vaccine candidate.

scholarly journals Dictyostelium discoideum as a Model System for Identification of Burkholderia pseudomallei Virulence Factors

2011 ◽  
Vol 79 (5) ◽  
pp. 2079-2088 ◽  
Author(s):  
Benjamin M. Hasselbring ◽  
Maharsh K. Patel ◽  
Mark A. Schell
Keyword(s):  
Dictyostelium Discoideum ◽  
High Throughput ◽  
Burkholderia Pseudomallei ◽  
Bacterial Pathogen ◽  
Model System ◽  
Virulence Determinants ◽  
Content Type ◽  
Throughput Model ◽  
Human Infections ◽  
High Throughput Assay

ABSTRACTBurkholderia pseudomalleiis an emerging bacterial pathogen and category B biothreat. Human infections withB. pseudomallei(called melioidosis) present as a range of manifestations, including acute septicemia and pneumonia. Although melioidosis can be fatal, little is known about the molecular basis ofB. pseudomalleipathogenicity, in part because of the lack of simple, genetically tractable eukaryotic models to facilitateen masseidentification of virulence determinants or explore host-pathogen interactions. Two assays, one high-throughput and one quantitative, were developed to monitor levels of resistance ofB. pseudomalleiand the closely related nearly avirulent speciesBurkholderia thailandensisto predation by the phagocytic amoebaDictyostelium discoideum. The quantitative assay showed that levels of resistance to, and survival within, amoeba by these bacteria and their known virulence mutants correlate well with their published levels of virulence in animals. Using the high-throughput assay, we screened a 1,500-memberB. thailandensistransposon mutant library and identified 13 genes involved in resistance to predation byD. discoideum. Orthologs of these genes were disrupted inB. pseudomallei, and nearly all mutants had similarly decreased resistance to predation byD. discoideum. For some mutants, decreased resistance also correlated with reduced survival in and cytotoxicity toward macrophages, as well as attenuated virulence in mice. These observations suggest that some factors required byB. pseudomalleifor resistance to environmental phagocytes also aid in resistance to phagocytic immune cells and contribute to disease in animals. Thus,D. discoideumprovides a novel, high-throughput model system for facilitating inquiry intoB. pseudomalleivirulence.

scholarly journals Current Advances in Burkholderia Vaccines Development

Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2671
Author(s):  
Guanbo Wang ◽  
Paulina Zarodkiewicz ◽  
Miguel A. Valvano
Keyword(s):  
Burkholderia Cepacia ◽  
Burkholderia Pseudomallei ◽  
Vaccine Development ◽  
Respiratory Infections ◽  
Bacterial Species ◽  
Antimicrobial Treatment ◽  
Burkholderia Cepacia Complex ◽  
Attractive Alternative ◽  
Wide Range ◽  
Substantial Progress

The genus Burkholderia includes a wide range of Gram-negative bacterial species some of which are pathogenic to humans and other vertebrates. The most pathogenic species are Burkholderia mallei, Burkholderia pseudomallei, and the members of the Burkholderia cepacia complex (Bcc). B. mallei and B. pseudomallei, the cause of glanders and melioidosis, respectively, are considered potential bioweapons. The Bcc comprises a subset of Burkholderia species associated with respiratory infections in people with chronic granulomatous disease and cystic fibrosis. Antimicrobial treatment of Burkholderia infections is difficult due to the intrinsic multidrug antibiotic resistance of these bacteria; prophylactic vaccines provide an attractive alternative to counteract these infections. Although commercial vaccines against Burkholderia infections are still unavailable, substantial progress has been made over recent years in the development of vaccines against B. pseudomallei and B. mallei. This review critically discusses the current advances in vaccine development against B. mallei, B. pseudomallei, and the Bcc.

scholarly journals Health inequality in the tropics and its costs: a Sustainable Development Goals alert

2020 ◽  
Vol 12 (5) ◽  
pp. 395-410
Author(s):  
Emily J Callander ◽  
Stephanie M Topp
Keyword(s):  
Health Inequality ◽  
Communicable Disease ◽  
Economic Cost ◽  
Middle Income ◽  
Disability Adjusted Life ◽  
Life Years ◽  
Disease Study ◽  
The Tropics ◽  
Lower Income Countries ◽  
The Impact

Abstract Background It is known that health impacts economic performance. This article aims to assess the current state of health inequality in the tropics, defined as the countries located between the Tropic of Cancer and the Tropic of Capricorn, and estimate the impact of this inequality on gross domestic product (GDP). Methods We constructed a series of concentration indices showing between-country inequalities in disability-adjusted life years (DALYs), taken from the Global Burden of Disease Study. We then utilized a non-linear least squares model to estimate the influence of health on GDP and counterfactual analysis to assess the GDP for each country had there been no between-country inequality. Results The poorest 25% of the tropical population had 68% of the all-cause DALYs burden in 2015; 82% of the communicable, maternal, neonatal and nutritional DALYs burden; 55% of the non-communicable disease DALYs burden and 61% of the injury DALYs burden. An increase in the all-cause DALYs rate of 1/1000 resulted in a 0.05% decrease in GDP. If there were no inequality between countries in all-cause DALY rates, most high-income countries would see a modest increase in GDP, with low- and middle-income countries estimated to see larger increases. Conclusions There are large and growing inequalities in health in the tropics and this has significant economic cost for lower-income countries.

scholarly journals A Persisting Nontropical Focus of Burkholderia pseudomallei with Limited Genome Evolution over Five Decades

mSystems ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Jessica R. Webb ◽  
Nicky Buller ◽  
Audrey Rachlin ◽  
Clayton Golledge ◽  
Derek S. Sarovich ◽  
...  
Keyword(s):  
Western Australia ◽  
Burkholderia Pseudomallei ◽  
Sequence Type ◽  
Genomic Islands ◽  
Genomic Diversity ◽  
Temperate Region ◽  
Content Type ◽  
High Rainfall ◽  
Climatic Regions ◽  
The Tropics

ABSTRACT Burkholderia pseudomallei is the causative agent of the high-mortality disease melioidosis. Although melioidosis is classified as a tropical disease, rare autochthonous cases have been reported from temperate climatic regions, with uncertainty as to whether B. pseudomallei is persistent in the local environment and whether specific genetic mechanisms facilitate the survival of B. pseudomallei outside the tropics. Sporadic cases of melioidosis occurred in a valley region (latitude 31.6°S) in southwest Western Australia, Australia, between 1966 and 1992. We report a new melioidosis cluster in the same region following high rainfall in January 2017. More than 20 animals died, and B. pseudomallei was isolated from four alpacas, a parrot, and three environmental samples taken from the farm where the alpacas resided. Epidemiological data and genomics revealed that two locations on the farm were the probable sources of the alpaca infections. We determined that B. pseudomallei isolates from the 2017 cluster belonged to sequence type 284 (ST-284), as did all isolates recovered from 1966 to 1992. Genomic analysis confirmed that the ST-284 isolates were clonal and contained conserved genomic islands and limited evidence of recombination. We identified protein-coding regions unique to these isolates that might influence the persistence of B. pseudomallei in this temperate region. We demonstrate the environmental persistence of B. pseudomallei in a temperate region for over 50 years, with limited genetic changes suggesting a latent state and with activation, potential aerosolization, and local dispersal following unusually high rainfall. IMPORTANCE Burkholderia pseudomallei is predominantly a tropical pathogen uncommonly found in the environment of temperate climatic regions. It is unclear if introduction into temperate regions is sporadic and temporary or if B. pseudomallei can persist in such environments. B. pseudomallei was identified in the environment of southwest Western Australia with melioidosis cases between 1966 and 1991. We report a new cluster with 23 animal fatalities in the same region from 2017, with B. pseudomallei again being recovered from the environment. Comparison of the isolates from the first and second clusters using genomics revealed a single sequence type, high clonality, and limited recombination, even though the time of recovery of the isolates spanned 51 years. This is a major contrast to the extensive genomic diversity seen in the tropics. Our data support the suggestion that B. pseudomallei has the ability to persist in nontropical environments, potentially in a latent state, and has the ability to activate following favorable conditions (rainfall) and then infect animals and humans.

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