Search Results (120)

Melioidosis, caused by Burkholderia pseudomallei, is a severe infectious disease with high mortality. Diagnostic delays due to conventional culture and serology limitations impact patient outcomes. This narrative review synthesizes evidence on next-generation sequencing (NGS) in melioidosis. NGS technologies encompass two main applications: metagenomic NGS (mNGS), which enables culture-independent detection directly from clinical samples, and whole-genome sequencing (WGS), which provides outbreak tracing and source attribution from cultured isolates. Resistance profiling detects antimicrobial resistance (AMR) determinants (e.g., penA mutations) to guide therapy. Recent 2025–2026 studies highlight new applications, including direct pathogen genome recovery from environmental samples. Despite cost and standardization challenges, integrating NGS into clinical workflows holds promise for improving melioidosis management, especially in resource-limited settings. Full article

Background/Objectives: Melioidosis is an environmentally acquired infection caused by Burkholderia pseudomallei (B. pseudomallei). Although historically framed as a tropical disease, evidence indicates that recognized risk can extend beyond classical endemic regions. This narrative review synthesized Digital Object Identifier (DOI)-verified evidence on environmental persistence, climate-sensitive risk, geographic emergence, and One Health preparedness. Methods: Structured narrative searches of PubMed/Medical Literature Analysis and Retrieval System Online (MEDLINE), Europe PubMed Central (Europe PMC), Crossref, and publisher records were conducted for literature available up to 19 June 2026. Forty-four DOI-verified sources were retained. Evidence categories were derived inductively by inferential function during thematic synthesis and used as a qualitative interpretive framework, not as a validated quantitative risk score. Results: B. pseudomallei persists in soil and water, survives nutrient limitation, and clusters in environmental microfoci, but the interpretive value of detection depends on viability, exposure context, and diagnostic endpoint. Rainfall, humidity, flooding, and cyclones are associated with incidence, severity, or mobilization in several settings, supporting climate-sensitive risk rather than uniform geographic spread. Case-based evidence is strongest when it separates importation, local acquisition, environmental establishment, source attribution, and animal sentinel signals. Human risk depends on exposure route, host susceptibility, diagnostic recognition, and access to prolonged antimicrobial management, whereas animal evidence is best interpreted as sentinel or common-exposure evidence unless reservoir or direct-transmission data are available. Conclusions: Melioidosis beyond the tropics requires graded evidence interpretation because environmental detection, modeled suitability, animal signals, and human cases support different levels of geographic and One Health inference; this approach links early signals to surveillance while reserving higher-confidence claims for convergent evidence. Full article

Melioidosis is rarely reported from Bali, Indonesia. This study aimed to determine whether Burkholderia pseudomallei was being misidentified. One hundred isolates that had been previously otherwise identified were screened using PCR targeting two specific genes and sequencing. Five were confirmed as B. pseudomallei and had been misidentified as Pseudomonas aeruginosa. Full article

Background: Melioidosis correlates strongly with rainfall, and there is substantial diversity in climate between melioidosis-endemic locations. The Northern Territory of Australia epitomises the “wet/dry” tropics, with a prolonged dry season from May to October. We analysed dry season cases of melioidosis during 35 consecutive years and compared these with wet season cases. We aimed to provide insights into how dry season cases of melioidosis may occur in this region and explore non-rainfall exposures that are usually not considered in the wet season. Methods: Case epidemiological and clinical data were extracted from the Darwin Prospective Melioidosis Study. Weather parameters, including daily rainfall, were analysed using generalised additive models and conditional logistic regressions to assess associations between dry season cases and preceding rainfall. Results: Of 1520 melioidosis cases between 1989 and 2024, there were 325 (21%) in the dry season. While the well-recognised clinical diversity of melioidosis was also seen amongst dry season cases, pneumonia was proportionally less common and cutaneous melioidosis was more common than in the wet season. A total of 23% of dry season patients had no identified clinical risk factors for melioidosis, compared to 14% in the wet season. Mortality was 8% in the dry season and 11% in the wet season. There was a range of plausible explanations for many of the dry season cases, including unseasonal rainfall prior to infection. Infections in urban settings were notable, with anthropogenic factors such as irrigation and construction resulting in persistence of Burkholderia pseudomallei in the environment during the dry season. A total of 3% of cases remained unexplained. Conclusions: Not all dry season cases are explained by infection occurring the previous wet season or by unseasonal rainfall in the dry. Identification of cases in the dry season support the need for year-round prevention strategies during potential exposure to contaminated water or soil. Further prospective studies are needed to better define the infecting events resulting in melioidosis, especially in the dry season. These studies should include timely history taking from the case and their family and selected environmental sampling for B. pseudomallei. Full article

Background: Burkholderia pseudomallei, the causative agent of melioidosis, infects diverse animal species and reflects environmental contamination. However, the global seroprevalence of B. pseudomallei in animals remains incompletely characterized. Methods: A systematic review and meta-analysis were conducted according to PRISMA guidelines and registered in PROSPERO (CRD420261306404). PubMed, Embase, and Scopus were searched for observational studies reporting seroprevalence of B. pseudomallei in animals. Random-effects meta-analysis was performed to estimate the pooled prevalence with 95% confidence intervals (CIs). Subgroup analyses were conducted by animal group, geographic region, diagnostic method, and indirect hemagglutination assay (IHA) cut-off value. Risk of bias was assessed using the Joanna Briggs Institute checklist. Results: Twenty studies involving 78,914 animals were included. The pooled seroprevalence of B. pseudomallei was 11% (95% CI: 6–19%), with substantial heterogeneity (I² = 98.1%, p < 0.0001). Wildlife showed the highest prevalence (16%; 95% CI: 10–25%), followed by livestock (11%; 95% CI: 6–19%). Significant geographic variation was observed (p < 0.0001), with higher prevalence reported in North America (18%) and Southeast Asia (10%). Seroprevalence estimates varied according to diagnostic method and IHA cut-off values. Sensitivity analyses yielded similar pooled prevalence estimates after exclusion of small studies, supporting the stability of the overall findings despite persistent heterogeneity. Conclusions: Exposure to B. pseudomallei is widespread among animal populations and influenced by geographic and methodological factors. Standardized diagnostic approaches and expanded animal surveillance are needed to improve understanding of melioidosis epidemiology within a One Health framework. Full article

Background/Objectives: Melioidosis, caused by Burkholderia pseudomallei, is a severe tropical infectious disease associated with high mortality in endemic regions. Early diagnosis remains challenging because conventional diagnostic methods, including culture, serological assays, and molecular techniques, have limitations in sensitivity, specificity, processing time, and accessibility in resource-limited settings. This review evaluates current diagnostic approaches and highlights the potential of short peptide biomarkers for improving melioidosis detection. Methods: A narrative literature review was conducted using four electronic databases (PubMed, Scopus, Web of Science, and Google Scholar) covering publications from 2000 to 2024. Relevant studies were identified using predefined keywords related to melioidosis diagnostics, biomarkers, and peptide-based approaches, and were screened based on relevance to diagnostic methods and peptide biomarker development in Burkholderia pseudomallei. Results: Several biomarkers have been investigated for melioidosis diagnostics, including capsular polysaccharide (CPS), type III secretion system 1 (TTS1), and other virulence-associated proteins such as Hcp1 and BPSS1187. Among these, CPS and TTS1 are highly conserved and specific targets widely used in molecular and antigen-based detection methods. Short peptide epitopes derived from these antigens demonstrate promising advantages over whole proteins, including improved stability, high specificity, easier synthesis, and reduced production costs. Advances in epitope prediction technologies and peptide-based biosensors have further expanded the potential applications of short peptides in rapid diagnostic platforms, including ELISA, lateral flow immunoassays, and biosensor-based detection systems. Conclusions: Short peptide–based biomarkers represent a promising strategy for developing rapid, sensitive, and cost-effective diagnostic tools for melioidosis, particularly in endemic and resource-limited settings. Full article

Background: Procalcitonin (PCT) is a biomarker of bacterial infection and sepsis severity, but its role in melioidosis remains unclear. This study aimed to synthesize available evidence on serum PCT levels in culture-confirmed melioidosis and explore associations with disease severity and mortality. Methods: We conducted a systematic review following PRISMA guidelines and registered the protocol with PROSPERO (CRD420251166979). PubMed, Embase, and Scopus were searched up to 30 October 2025. Observational studies reporting serum PCT levels in microbiologically confirmed melioidosis were included. Study quality was assessed using the Newcastle–Ottawa Scale (NOS) for observational studies. Random-effects models were used to calculate pooled mean PCT levels, with heterogeneity assessed by I². Sensitivity analyses were performed to explore the influence of historical and small-sample studies. Results: Seven studies comprising 284 patients with culture-confirmed melioidosis were included. The pooled mean PCT level was 14.46 ng/mL (95% CI: 4.59–24.33), with substantial heterogeneity (I² = 87.7%). Sensitivity analyses excluding the oldest study and the smallest sample size reduced heterogeneity but retained consistently elevated PCT levels across cohorts. Higher PCT concentrations were consistently observed among patients with septic shock, bacteremia, and fatal outcomes, although variability in definitions precluded quantitative synthesis of prognostic effect sizes. These findings were based on heterogeneous study-level comparisons and could not be synthesized quantitatively. Conclusions: PCT is markedly elevated in melioidosis and reflects the severity of systemic infection, supporting its potential role as an adjunctive biomarker for early risk stratification. However, substantial heterogeneity and limited sample sizes prevent the establishment of a melioidosis-specific prognostic threshold. Standardized, prospective, multicenter studies are required to clarify the independent prognostic value of PCT in melioidosis management. This study establishes a pooled estimate of serum PCT levels in melioidosis and demonstrates that these values are comparable to those observed in severe bacterial sepsis, supporting its interpretation as a marker of systemic inflammatory burden rather than a disease-specific biomarker. Full article

Burkholderia pseudomallei, the causative agent of melioidosis, presents significant challenges in both treatment and environmental decontamination. Bacteriophages, or phages, are increasingly being explored as potential diagnostic, therapeutic, and biocontrol agents against this bacterial pathogen. Our recent investigation has shown that most B. pseudomallei genomes contained prophage(s) associated with specific tRNA gene loci, prompting us to explore these detectable prophages as sources of temperate phages for further applications. Transcriptomic profiling of B. pseudomallei Bp82, a model strain that possesses three different prophages, revealed high expression levels of the integrase and certain transcriptional regulatory genes within its prophages during normal exponential growth. Using one of its temperate phages, namely φBP82.2, a P2-like phage, as a model, we investigated the lysogenic–lytic control mechanisms. Mutagenesis of the integrase gene, phiBP82.2_gp51, did not improve killing activity compared to the wildtype phage. In contrast, deletion of phiBP82.2_gp38, a putative transcriptional regulatory gene, and two downstream hypothetical protein genes, phiBP82.2_gp36 and phiBP82.2_gp37, resulted in significant lytic improvement. We conclude that these genes play a crucial role in the lysogenic–lytic switch of φBP82.2, suggesting a new avenue for engineering temperate phages for future applications. Full article

Burkholderia pseudomallei is a saprophytic environmental bacterium and the causative agent of melioidosis, a serious opportunistic infection in tropical regions, including northern Australia. Infection occurs following environmental exposure via percutaneous inoculation, ingestion, or inhalation; however, the environmental reservoirs and transmission pathways responsible for human disease remain poorly defined. Groundwater has been implicated as a potential source of infection, but the factors influencing the persistence and mobility of B. pseudomallei in surface waters in North Queensland are not well understood. Water samples were collected from a groundwater-connected seasonal creek in Townsville, North Queensland, over a 12-month period encompassing wet and dry seasons. Samples were cultured on Ashdown agar and confirmed as B. pseudomallei by qPCR. Multi-locus sequence typing (MLST) was performed using targeted allele sequencing on the Oxford Nanopore MinION platform. Eighteen of 59 water samples were culture-positive for B. pseudomallei. Detection occurred exclusively in turbid, flowing water following ≥30 mm of rainfall and was observed in both wet and dry seasons. MLST of 48 isolates identified 18 sequence types, including 12 novel types. Six sequence types matched previously reported Townsville clinical isolates. These findings indicate that groundwater from a connected urban creek may function as a mobile reservoir for clinically relevant B. pseudomallei strains under specific hydrological and climatic conditions, highlighting rainfall-driven processes as key drivers of environmental exposure risk. Full article

Background: Melioidosis is a potentially fatal infectious disease caused by Burkholderia pseudomallei and is highly prevalent in tropical regions. Diabetes mellitus (DM) is the most common comorbidity among patients with melioidosis and is a well-established risk factor for acquiring the infection. However, the impact of diabetes on disease severity and mortality remains uncertain. Methods: We conducted a systematic review and meta-analysis of observational studies to evaluate the association between diabetes mellitus and severe clinical outcomes in patients with melioidosis. PubMed, Embase, and Scopus were searched from database inception to 6 January 2026. Outcomes of interest included bacteremia, septic shock, intensive care unit (ICU) admission, and mortality. Pooled odds ratios with 95% confidence intervals (CIs) were calculated using random-effects models. Heterogeneity was assessed using the I² statistic. The review was registered in PROSPERO (CRD420251237028). Results: Twelve studies comprising patients from Southeast Asia, Australia, and South Asia were included. Diabetes prevalence among patients with melioidosis ranged from 31% to 76%. Meta-analysis showed no significant association between diabetes mellitus and bacteremia (OR 1.48, 95% CI 0.97–2.27), ICU admission (OR 1.31, 95% CI 0.43–3.99), septic shock (OR 0.67, 95% CI 0.39–1.16), or mortality (OR 0.82, 95% CI 0.66–1.03). Subgroup analysis revealed lower mortality among patients with diabetes in Southeast Asia (OR 0.74, 95% CI 0.61–0.91), while no significant association was observed in Australia. Heterogeneity varied across outcomes and regions. Conclusions: Although diabetes mellitus is a major risk factor for acquiring melioidosis, our findings suggest that it is not consistently associated with increased disease severity or mortality once infection occurs. These results should be interpreted cautiously given the limited number of included studies, heterogeneity across outcomes, and potential residual confounding. Further prospective studies are required to better define the underlying biological and healthcare-related mechanisms. Full article

Melioidosis is increasingly recognised in tropical and subtropical regions worldwide as a serious and potentially fatal bacterial infection affecting humans and animals, acquired from the environment. Until now, human cases of melioidosis had not been reported in Southern Africa. Over a four-year period, we identified three human and two animal cases of melioidosis in South Africa and Namibia. Burkholderia pseudomallei isolates were investigated by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) and whole-genome sequencing (WGS). Phylogenetic analysis demonstrated substantial diversity, suggesting long-term cryptic persistence of the bacterium in the Southern African region. Limited awareness of the disease and inadequate diagnostic capacity likely contribute to its apparent rarity in the region. These findings underscore the urgent need for increased surveillance, improved diagnostics, and greater awareness of melioidosis in Southern Africa to better understand its true epidemiological burden and prevent future cases. Full article

Background: Melioidosis, caused by Burkholderia pseudomallei, is a severe and often underdiagnosed infection endemic to South Asia, Southeast Asia, and northern Australia. While pneumonia and sepsis are the classical presentations, the disease is increasingly recognized for its diverse and atypical clinical manifestations. Objective: The objective is to improve diagnostic accuracy and increase clinical awareness in both endemic and non-endemic settings by reviewing and classifying atypical presentations of melioidosis that have been documented in the literature. Methods: A narrative, case-based review was conducted using 238 published case reports and series from endemic and transitional regions during the period from 2000 to 2025. Cases with non-respiratory presentations or anatomical locations not commonly linked to melioidosis were classified as atypical. Clinical syndromes were used to classify the extracted cases, and common patterns in presentation, diagnosis, and outcome were examined. Results: One hundred and sixty published articles were included after a full text review. The most frequent atypical presentations included neurological involvement (e.g., brain abscess, encephalomyelitis), musculoskeletal infections (osteomyelitis, myositis), thyroid abscess, tubo-ovarian abscess, and dermatologic manifestations such as erythema nodosum. Imported and pediatric cases were also found. Numerous cases were misidentified as cancer, fungal infections, or tuberculosis. Among risk factors, diabetes mellitus was the most prevalent. Non-specific symptoms, a lack of laboratory capacity, and incorrect pathogen identification frequently resulted in delays in diagnosis. Conclusions: In endemic areas, melioidosis should be taken into account when making a differential diagnosis of a variety of clinical syndromes, especially in patients who have diabetes or have had relevant environmental exposure. Poor outcomes and diagnostic delays are greatly exacerbated by atypical presentations. Improving diagnostic capabilities and raising awareness are crucial to lessening the worldwide burden of this often ignored but potentially deadly infection. Full article

Burkholderia pseudomallei, the causative agent of melioidosis, is endemic in Sarawak, Malaysian Borneo, where it is represented by a unique gentamicin-susceptible population. Despite trimethoprim-sulfamethoxazole (co-trimoxazole) being the cornerstone of eradication therapy, emerging reports of elevated minimum inhibitory concentrations (MICs) among Sarawak isolates have raised concerns over its clinical efficacy. We performed a retrospective and comprehensive antibiotic susceptibility assessment of clinical B. pseudomallei isolates from hospitals across Sarawak. Susceptibility to trimethoprim-sulfamethoxazole was determined using disk diffusion and the E-test, interpreted by both CLSI and EUCAST guidelines. Resistance to the individual components, trimethoprim and sulfamethoxazole, was characterized by broth microdilution. The results demonstrated a high prevalence of trimethoprim-sulfamethoxazole susceptibility, with 96.3% of isolates susceptible by CLSI criteria and 97.6% by EUCAST criteria. Interestingly, broth microdilution revealed that resistance to trimethoprim and sulfamethoxazole individually did not confer resistance to the synergistic combination. Our analysis validated CLSI guidelines as the most reliable standard for antimicrobial resistance surveillance in this region. This study provides evidence that trimethoprim-sulfamethoxazole remains effective for melioidosis treatment in Sarawak, offering crucial reassurance to clinicians. The paradoxical finding of susceptibility to the drug combination despite resistance to its individual components underscores the critical importance of the synergistic activity of trimethoprim-sulfamethoxazole and highlights the need for further investigation into the molecular basis of resistance in this distinct B. pseudomallei population. Full article

Burkholderia pseudomallei complex and B. cepacia complex are two evolutionary distinct clades of pathogens causing human disease. Most vaccine efforts have focused on the former group largely due to their biothreat status and global disease burden. It has been proposed that a vaccine could be developed that simultaneously protects against both groups of Burkholderia by specifically targeting conserved antigens. Only a few studies have set out to identify which antigens may be optimal targets for such a vaccine. We have previously assessed the ability of three highly conserved B. pseudomallei antigens, namely OmpA1, OmpA2, and Pal, coupled to gold nanoparticle vaccines, to protect mice against a homotypic B. pseudomallei challenge. Here, we have expanded our study by demonstrating that antibodies to each of these proteins show varying levels of reactivity to homologues in B. cepacia complex, with OmpA2 antibodies exhibiting the highest cross-reactivity. Remarkably, some nanovaccine immunized mice, particularly those that received OmpA2, produced antibodies that bind Pseudomonas aeruginosa, which harbors distantly related homologous proteins. T cells elicited to Pal and OmpA2 responded to stimulation with B. cepacia complex-derived homologues. Our study supports incorporation of these antigens, particularly OmpA2, for the development of a pan-Burkholderia vaccine. Full article

Background: Travel-associated melioidosis, caused by Burkholderia pseudomallei, is increasingly reported in non-endemic countries due to rising global travel. Understanding demographic, clinical, and outcome patterns of imported cases is important to improve recognition and management in settings where melioidosis is uncommon. Methods: We systematically searched PubMed, Embase, and Scopus (last search: 24 September 2025) for case reports and case series of melioidosis diagnosed outside endemic regions and linked to travel exposure. Data were extracted on demographics, comorbidities, clinical manifestations, and outcomes. We performed descriptive analyses, subgroup analyses, and Firth’s penalized logistic regression to explore predictors of death. The protocol was registered in PROSPERO (CRD420251154559). Results: A total of 104 studies, encompassing 143 individual cases, were included. Most diagnoses occurred in non-endemic, high-income countries, especially the Netherlands (21%), France (10%), the United States (9%), and South Korea (7%). Infections were predominantly acquired in Southeast Asia, particularly Thailand (39%). The mean patient age was 50.6 years, with a male predominance (78%). Diabetes mellitus was the most frequent comorbidity (28%). Clinical presentations included pulmonary (33%), sepsis (27%), cutaneous (13%), abdominal (4%), and osteoarticular disease (1%). Overall mortality was 12.6% and relapse occurred in 7%. In penalized regression analyses, no baseline characteristic was statistically significantly associated with mortality; septic presentation showed an elevated point estimate for odds of death, but with imprecise estimates. Conclusions: Travel-associated melioidosis is a rare but clinically significant imported infection. Most cases followed exposure in Southeast Asia, and pulmonary disease and sepsis were the most frequent presentations. Mortality remained substantial (12.6%), and relapse was reported in 7%, underscoring the need for early recognition, appropriate therapy, and follow-up in non-endemic settings. Full article