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Melioidosis, caused by the intracellular bacterial pathogen and Tier 1 select agent Burkholderia pseudomallei (Bp), is a highly fatal disease endemic in tropical areas. No licensed vaccine against melioidosis exists. In preclinical vaccine studies, demonstrating protection against respiratory infection in the highly sensitive BALB/c mouse has been especially challenging. To address this challenge, we have used a safe yet potent live attenuated platform vector, LVS ΔcapB, previously used successfully to develop vaccines against the Tier 1 select agents of tularemia, anthrax, and plague, to develop a melioidosis vaccine. We have engineered melioidosis vaccines (rLVS ΔcapB/Bp) expressing multiple immunoprotective Bp antigens among type VI secretion system proteins Hcp1, Hcp2, and Hcp6, and membrane protein LolC. Administered intradermally, rLVS ΔcapB/Bp vaccines strongly protect highly sensitive BALB/c mice against lethal respiratory Bp challenge, but protection is overwhelmed at very high challenge doses. In contrast, administered intranasally, rLVS ΔcapB/Bp vaccines remain strongly protective against even very high challenge doses. Under some conditions, the LVS ΔcapB vector itself provides significant protection against Bp challenge, and consistent with this, both the vector and vaccines induce humoral immune responses to Bp antigens. Three-antigen vaccines expressing Hcp6-Hcp1-Hcp2 or Hcp6-Hcp1-LolC are among the most potent and provide long-term protection and protection even with a single intranasal immunization. Protection via the intranasal route was either comparable to or statistically significantly better than the single-deletional Bp mutant Bp82, which served as a positive control. Thus, rLVS ΔcapB/Bp vaccines are exceptionally promising safe and potent melioidosis vaccines.ImportanceMelioidosis, a major neglected disease caused by the intracellular bacterial pathogen Burkholderia pseudomallei, is endemic in many tropical areas of the world and causes an estimated 165,000 cases and 89,000 deaths in humans annually. Moreover, B. pseudomallei is categorized as a Tier 1 select agent of bioterrorism, largely because inhalation of low doses can cause rapidly fatal pneumonia. No licensed vaccine is available to prevent melioidosis. Here, we describe a safe and potent melioidosis vaccine that protects against lethal respiratory challenge with B. pseudomallei in a highly sensitive small animal model-even a single immunization is highly protective, and the vaccine gives long-term protection. The vaccine utilizes a highly attenuated replicating intracellular bacterium as a vector to express multiple key proteins of B. pseudomallei; this vector platform has previously been used successfully to develop potent vaccines against other Tier 1 select agent diseases including tularemia, anthrax, and plague.

Burkholderia pseudomallei causes melioidosis, a deadly infection having high fatality rates (20–50%) and antibiotic resistance, however, there's no effective drug or vaccine available. Trehalose is a vital sugar for B. pseudomallei which influences the pathogen resilience and pathogenicity. This proposed computational strategy focuses on developing novel drugs against Trehalose-6-phosphate Phosphatase (TPP) to combat infections. This study found three novel drugs from Asinex, Zinc, Chembridge, and Drugbank databases through a comprehensive structure-based virtual screening. The process screened the top three compounds: BDG_34042863, BDF_33738612, and DB00139 along with control (2-methyl-6-phenoxytetrahydro-2 H-pyran-3,4,5-triol) with a binding energy score of -8.8 kcal/mol, -8.4 kcal/mol, and − 7.7 kcal/mol, -6.4 kcal/mol respectively. In a molecular dynamics simulation, the Ligand-protein complexes demonstrated substantial non-covalent interactions as well as a stable docked intermolecular binding conformation. Throughout the MDS (molecular dynamic simulation) period, the studied compounds showed stable consistent interactions; there were no noticeable changes in the interactions or binding mode. The BDG_34042863, BDF_33738612, and DB00139 had a mean deviation of 4.04, 7.18, and 7.10 measured in Å, respectively. In addition, the simulation trajectories of complexes underwent MM/GBSA analysis, which revealed binding affinity scores of -33.39, -41.1, -49.16, and − 41.29 measured in kcal/mol for the control, BDG_34042863, BDF_33738612, and DB00139, respectively. According to DFT Analysis, BDF_33738612 showed the smallest energy gap (0.46 eV), indicating high reactivity, while DB00139 showed the largest energy gap (5.66 eV), illustrating good kinetic stability compared to the control. The compounds exhibit notable differences in reactivity and stability levels as their HOMO-1 to LUMO + 1 and HOMO-2 to LUMO + 2 orbitals have greater energy gaps, ranging from 5.06 eV to 6.69 eV and 5.66 eV to 7.09 eV, respectively. The compounds also had favorable pharmacokinetic characteristics and were categorized as druglike. Among the selected compounds, BDF_33738612 demonstrated the most promising findings followed by BDG_34042863 and DB00139. The compounds may be employed in an experimental study to examine their anti-TPP activity against B. pseudomallei. [ABSTRACT FROM AUTHOR]

Background: Glanders and melioidosis are contagious zoonotic diseases caused by Burkholderia mallei and B. pseudomallei, respectively. Bacterial isolation and polymerase chain reaction (PCR) have been used to detect these bacteria in animals suspected of infection; however, both methods require skilled experimental techniques and expensive equipment. These obstacles make it difficult to diagnose B. mallei and B. pseudomallei infections in areas where reagents and equipment are difficult to procure. To solve this problem, we developed an easy and ready-to-use dried-format diagnostic tool based on loop-mediated isothermal amplification (LAMP) method. Results: The primer set targeting the internal transcribed spacer (ITS) region detected 10 genomic copies of B. mallei DNA and B. pseudomallei DNA using the conventional liquid LAMP method. This primer set did not detect any other Burkholderia species. Using this novel primer set, a dried-format in-house LAMP method with high sensitivity and specificity was developed. This method was used to test for the presence of B. mallei DNA in swabs collected from the nasal cavity and ulcerated skin of 19 B. mallei-infected horses and five uninfected horses and was compared with the real-time PCR method. These two tests showed 87.5% agreement for the positive samples and 100% agreement for the negative samples. This method detected all tested B. pseudomallei clinical isolates. Conclusions: We established the first dry LAMP method for the detection of B. mallei and B. pseudomallei. This study provided a simple, rapid, cost-effective, and sensitive diagnostic tool for glanders and melioidosis. [ABSTRACT FROM AUTHOR]

Melioidosis is a disease endemic to India but often goes unrecognized, leading to considerable illness and death. We present the case of a 31-year-old man who had a fever of unknown origin, abnormal renal and liver function tests, and negative tests for dengue, typhoid, leptospirosis, and scrub typhus. Imaging revealed multiple splenic infarcts. Initially suspected to be malaria due to its prevalence in South India, further investigation uncovered pneumonia along with several liver and splenic abscesses, raising the possibility of melioidosis. Blood culture eventually identified Burkholderia pseudomallei , confirming the diagnosis. As malaria cases decline in Southeast Asia, emergency physicians should consider melioidosis in their differential diagnosis of acute febrile illnesses, especially in endemic areas. Early detection and prompt antibiotic treatment are vital for managing this often under-recognized disease with a high fatality rate. Thus, melioidosis should be considered in patients with unexplained fever in endemic regions, as early diagnosis and intervention can be life-saving. [ABSTRACT FROM AUTHOR]

Introduction: Melioidosis results from infection by Burkholderia pseudomallei. Clinical presentation ranges from asymptomatic infection to fulminant septicemia with septic shock. We describe a case where one patient with pneumonia and septic shock was found to have a disseminated abscesses there in the liver, spleen, and prostate. Case description: He was presented to the hospital emergency with septic shock and hypoxemic respiratory failure and transferred to the intensive care unit (ICU). Two sets of blood cultures sent at admission showed growth of nonlactose fermenting gram-negative rods. The organism was identified as B. pseudomallei by an automated VITEK2 Compact system. Computed tomography (CT) scan of the abdomen and pelvis revealed hepatomegaly with multiple abscesses, multiple splenic micro abscesses, prostatomegaly with multiple prostatic abscesses, and of thorax suggested multiple variable-sized nodules with subpleural consolidation. He received intravenous meropenem followed by ceftazidime for a total of 4 weeks. With clinical resolution, he was started on oral antibiotics trimethoprim-sulfamethoxazole and was discharged home to continue for 3 months. Discussion: Disseminated abscesses especially involving the liver and spleen are characteristics of melioidosis. Interestingly, in our case, a single patient had multifocal abscesses involving the liver, spleen, and prostate along with lung involvement. Conclusion: Melioidosis with disseminated abscess in a single patient especially of prostatic abscess as in our case has been rarely reported. [ABSTRACT FROM AUTHOR]

Burkholderia pseudomallei biofilm is a significant virulence factor in infection. This study aimed to investigate antibacterial and antibiofilm activities of Piper betle extract against B. pseudomallei. The MIC and MBC values of the extract against the isolates were 0.5–1.0 mg/mL. At 2 × MIC, the cells showed cell shrinkage and abnormalities. At 1/2 × MIC, the extract displayed 40–71% inhibition of biofilm formation. At 8 × MIC, the extract reduced the viability of mature biofilms by 60–86%. Hydroxychavicol and eugenol, the main compounds in the extract, showed binding activity to CdpA, an enzyme implicated in biofilms as observed by in silico studies. Hydroxychavicol exhibited the highest affinity for CdpA, with a distance of 2.27 Å. Molecular dynamics simulations revealed that hydroxychavicol forms a stable complex with cyclic di-GMP phosphodiesterase, maintaining protein structural integrity with minimal conformational changes. The results suggested that Piper betle may have medicinal benefits by inhibiting biofilm-related infections. [ABSTRACT FROM AUTHOR]

Nanozymes (nanomaterials with intrinsic enzyme-like characteristics) have gained much attention for diagnostics and therapy due to their excellent enzyme-mimicking capability, great stability in environments, and facile and low-cost production. However, developing nanozymes with a high catalytic constant, Kcat, has been challenging. Herein, we report a class of nanozyme-mimicking peroxidases, which are formed by depositing ultrasmall platinum nanoparticles (Pt NPs) 1–2 nm in size on the surface of hydrophilic nitrogen-doped carbon nanoparticles (CN NPs). These nanozymes defined as CN-Pt NPs show a high peroxidase-like activity with Kcat values of 1.27 M·mL/s·g for 3,3,5,5′-tetramethylbenzidine (TMB) and 1.97 M·mL/s·g for hydrogen peroxide (H2O2), respectively, which are at least one or two orders higher than many other reported carbon–noble metal-based nanozymes. Our developed CN-Pt NPs were further utilized in a colorimetric immunoassay as signal amplifiers for the biomarker detection of Burkholderia pseudomallei , a Gram-negative bacterial pathogen classified as a tier 1 select agent by the US CDC. The assay achieved lower limits of detection of 0.11 ng/mL in phosphate-buffered saline (PBS) and 0.16 ng/mL in human serum, when compared to many other assays in detecting the same biomarker. [ABSTRACT FROM AUTHOR]

Background Case report Conclusion Melioidosis, caused by Burkholderia pseudomallei, is an important disease that is endemic in areas of northern Australia and can cause a wide range of clinical signs in people and animals. There is limited published data on the disease in marsupials.Two captive red‐legged pademelons (Thylogale stigmatica) with collective signs of lethargy, dysphagia and bloody oral discharge were submitted for necropsy and showed variations in pathology findings ranging from multifocal abscessation in various tissues to evidence of fulminant septicaemia. In both cases Burkholderia pseudomallei was confirmed by bacterial culture and qPCR.This report details the first report of melioidosis in captive red‐legged pademelons (Thylogale stigmatica) and describes the variations in clinical signs and pathological findings that were encountered with the disease. More research is needed to better understand melioidosis in marsupials to aid clinicians in making a prompt diagnosis. [ABSTRACT FROM AUTHOR]

Background: Burkholderia pseudomallei, causative agent of melioidosis, is a One Health concern as it is acquired directly from soil and water and causes disease in humans and agricultural and wild animals. We examined B. pseudomallei in soil and goats at a single farm in the Northern Territory of Australia where >30 goats acquired melioidosis over nine years. Methodology/Principal findings: We cultured 45 B. pseudomallei isolates from 35 goats and sampled soil in and around goat enclosures to isolate and detect B. pseudomallei and evaluate characteristics associated with its occurrence; 33 soil isolates were obtained from 1993–1994 and 116 in 2006. Ninety-two goat and soil isolates were sequenced; mice were challenged with six soil isolates to evaluate virulence. Sampling depth and total N/organic C correlated with B. pseudomallei presence. Twelve sequence types (STs) were identified. Most goat infections (74%) were ST617, some with high similarity to 2006 soil isolates, suggesting ST617 was successful at persisting in soil and infecting goats. ST260 and ST266 isolates were highly virulent in mice but other isolates produced low/intermediate virulence; three of these were ST326 isolates, the most common soil ST in 2006. Thus, virulent and non-virulent lineages can co-occur locally. Three genes associated with virulence were present in ST260 and ST266, absent in most ST326 isolates, and present or variably present in ST617. Conclusions/Significance: Agricultural animals can influence B. pseudomallei abundance and diversity in local environments. This effect may persist, as B. pseudomallei was detected more often from soil collected inside and adjacent to goat enclosures years after most goats were removed. Following goat removal, the low virulence ST326, which was not isolated from soil when goats were present, became the predominant ST in soil by 2006. Although multiple diverse lineages of B. pseudomallei may exist in a given location, some may infect mammals more efficiently than others. Author summary: We studied genomic diversity in the environmental bacterial pathogen, Burkholderia pseudomallei, which caused the disease melioidosis in goats at a small farm in northern Australia. By comparing genomes from 92 B. pseudomallei isolates from goats and soil, we discovered 12 diverse lineages at this location, three of which infected the majority of goats and were cultured from the soil of goat enclosures. We also conducted a mouse challenge experiment using six isolates from this farm and determined that two soil isolates displayed much greater virulence than the others. Finally, we investigated soil factors associated with B. pseudomallei occurrence and found 1) most B. pseudomallei isolates were sampled from irrigated soils, and 2) B. pseudomallei was much more likely to be encountered at soil depths of 30 cm than 10 cm. The presence of this pathogen in the soil severely impacted maintenance of the goat herd due to high mortality and emphasizes its One Health implications for other livestock operations in tropical countries where B. pseudomallei is endemic. Our findings provide insight into the importance of more fully understanding soil habitats that promote B. pseudomallei presence, thereby increasing the risk of melioidosis to humans and agricultural animals. [ABSTRACT FROM AUTHOR]

Respiratory viral infection may increase infection with Burkholderia pseudomallei progressing to clinical disease (melioidosis). This data linkage study evaluated associations between melioidosis and SARS-CoV-2 or influenza. Among 160 melioidosis cases, there was no difference in risk factors, vaccine status, or disease severity between 17 with viral co-infection and 143 without. [ABSTRACT FROM AUTHOR]

Vaccines have historically played a pivotal role in controlling epidemics. Effective vaccines for viruses causing significant human disease, e.g. , Ebola, Lassa fever, or Crimean Congo hemorrhagic fever virus, would be invaluable to public health strategies and counter-measure development missions. Here, we propose coverage metrics to quantify vaccine-induced CD8+ T cell-mediated immune protection, as well as metrics to characterize immuno-dominant epitopes, in light of human genetic heterogeneity and viral evolution. Proof-of-principle of our approach and methods are demonstrated for Ebola virus, SARS-CoV-2, and Burkholderia pseudomallei (vaccine) proteins. [ABSTRACT FROM AUTHOR]

Background and objectives: Melioidosis, caused by the gram-negative bacillus Burkholderia pseudomallei, is a major cause of fatal community acquired infection in diabetic patients. Protective immune response in human melioidosis is not clearly understood yet. In this study, serum IgM/IgG and bactericidal antibody response to B. pseudomallei were determined in diabetic patients with acute localized abscess and septicemia. Material and methods: Culture positive melioidosis cases with diabetes mellitus were included in the study. Blood samples were collected from the respective cases in active phase of the disease within 1 or 2 days of being culture positive. Anti- B. pseudomallei IgM and IgG and serum bactericidal antibody were measured by ELISA and microplate based bactericidal assay respectively. Results: A total of 10 culture positive acute melioidosis cases with diabetes mellitus were included in the study. Out of 10 cases, 5 had abscess in different organs and 5 had septicemia. The mean age of the patients was 48.5 ± 3.91 years and 7 (70%) were male and 3 (30%) were female. The mean anti- B. pseudomallei IgM titer of septicemic and abscess cases were not significantly different (14,080 ± 4,489.13 vs. 19,200 ± 3,620.39; p = 0.4) while the mean IgG titers of two groups were > 204,800. Out of 10 cases, 9 (90%) were positive for serum bactericidal antibody. Mean serum bactericidal antibody titer of septicemia cases (66 ± 26) was not significantly (p = 0.72) different than those of localized infection (80 ± 28.28). Conclusion: The results indicate that high anti- B. pseudomallei IgM/IgG and serum bactericidal antibodies are induced in diabetic patients with septicemia and suppurative infections. This immune response in diabetics might be important to contain the infection and help in recovery. January 2025; Vol. 19(1):009. DOI: https://doi.org/10.55010/imcjms.19.009 *Correspondence: Sraboni Mazumder, Department of Microbiology, Ibrahim Medical College, 1/A Ibrahim Sarani, Segunbaghicha, Dhaka, Bangladesh. Email: mazumder.sraboni@gmail.com; © 2025 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0).

Melioidosis is an emerging infection in India and is caused by a Gram-negative oxidase-positive bacilli, Burkholderia pseudomallei which is present in soil and surface water in the endemic region. Clinical manifestations are protean varying from asymptomatic infection, multiple skin abscesses, chronic pneumonia mimicking tuberculosis, and fulminant septic shock with abscesses in multiple internal organs. Isolation of bacilli from aspirated fluids remains the gold standard of diagnosis. Lack of microbiological services in many parts of the state, protean nature of clinical manifestations, lack of awareness among clinicians, and misidentification of the organism as Pseudomonas spp leads to delay in diagnosis and treatment. We have, retrospectively, analyzed 14 cases with culture-proven melioidosis diagnosed during 10 years. Case records of culture-positive patients were retrospectively analyzed for demographic data, clinical characteristics, management, complications, and clinical outcomes. Out of these, 13 cases were male. The most common age group affected was 50–59 years. The major occupation affected was manual laborer. Nonbacteremic melioidosis accounted for 12 cases. Concerning clinical presentations, intra-abdominal abscesses mainly in the liver and spleen accounted for seven cases. All the isolates were susceptible to ceftazidime, meropenem, and doxycycline, whereas 12 isolates were susceptible to chloramphenicol, 11 isolates were susceptible to trimethoprim–sulfamethoxazole combination, and 10 cases were susceptible to amoxicillin–clavulanic acid and ciprofloxacin. Ten cases recovered with ceftazidime administration along with surgical drainage of abscess and three cases recovered with meropenem administration and surgical drainage. One patient expired and was on piperacillin–tazobactam. Melioidosis is a disease of public health importance and early clinical and laboratory diagnosis is crucial in the effective management of melioidosis.

Melioidosis, caused by Burkholderia pseudomallei, is a challenging infectious disease with global implications, primarily affecting Southeast Asia. We present the case of a 24-year-old male with a curious history of tobacco use, presenting with fevers, weight loss, and genitourinary symptoms. Diagnostic challenges arose as symptoms mimicked other diseases. Disseminated melioidosis was confirmed via Gram staining and positron emission tomography scan findings, emphasizing the disease’s diverse clinical manifestations. Treatment with ceftazidime and cotrimoxazole led to prompt recovery. Notably, the patient’s tobacco use linked to contaminated water highlights a unique transmission route. This case underscores the need for heightened awareness and preventive measures in endemic regions.

Abstract Background Although there is a high incidence of hematogenous infections in melioidosis, a tropical infectious disease, there are few systematic analyses of hematogenous melioidosis in imaging articles. A comprehensive clinical and imaging evaluation of hematogenous melioidosis be conducted in order to achieve early diagnosis of the disease. Materials and methods We conducted an analysis of 111 cases of melioidosis diagnosed by bacteriological culture between August 2001 and September 2022. The analysis focused on observing the main manifestations of chest imaging and clinical data, including nodules, cavities, consolidation, ground glass opacity(GGO), pleural effusion, centrilobular nodules, and temperature, leucocyte count, diabetes, etc. Our study involved univariate and multivariate analyses to identify significant diagnostic variables and risk predictive factors. Results A total of 71.2% (79/111) of melioidosis cases were caused by hematogenous infection, and the most common organ involved was the lungs (88.5%, 100/113). The incidence of sepsis in patients with lung abnormalities was high (73%, 73/100), and the mortality rate of septic shock was 22% (22/100). Univariate analysis showed that the radiologic signs of blood culture-positive cases were more likely to have bilateral pulmonary and subpleural nodules (p = 0.003), bilateral GGO (p = 0.001), bilateral hydrothorax (p = 0.011). The multivariate analysis revealed a significant improvement in the area under the receiver operating characteristic curve (AUC) when comparing the model that included both clinical and radiologic variables to the model with clinical variables alone. The AUC increased from 0.818 to 0.932 (p = 0.012). The most important variables in the logistic regression with backward elimination were found to be nodule, GGO, and diabetes. Conclusion The combination of CT features and clinical variables provided a valuable and timely warning for blood borne infectious melioidosis.

In the United States in 2021, an outbreak of 4 cases of Burkholderia pseudomallei, the etiologic agent of melioidosis and a Tier One Select Agent (potential for deliberate misuse and subsequent harm), resulted in 2 deaths. The causative strain, B. pseudomallei ATS2021, was unintentionally imported into the United States in an aromatherapy spray manufactured in India. We established that ATS2021 represents a virulent strain of B. pseudomallei capable of robust formation of biofilm at physiologic temperatures that may contribute to virulence. By using mouse melioidosis models, we determined median lethal dose estimates and analyzed the bacteriologic and histopathologic characteristics of the organism, particularly the potential neurologic pathogenesis that is probably associated with the bimABm allele identified in B. pseudomallei strain ATS2021. Our data, combined with previous case reports and the identification of endemic B. pseudomallei strains in Mississippi, support the concept that melioidosis is emerging in the United States.

Abstract Melioidosis is a life-threatening tropical disease caused by an intracellular gram-negative bacterium Burkholderia pseudomallei. B. pseudomallei polymerizes the host cell actin through autotransporters, BimA, and BimC, to facilitate intracellular motility. Two variations of BimA in B. pseudomallei have been reported previously: BimABp and BimA B. mallei-like (BimABm). However, little is known about genetic sequence variations within BimA and BimC, and their potential effect on the virulence of B. pseudomallei. This study analyzed 1,294 genomes from clinical isolates of patients admitted to nine hospitals in northeast Thailand between 2015 and 2018 and performed 3D structural analysis and plaque-forming efficiency assay. The genomic analysis identified 10 BimABp and 5 major BimC types, in the dominant and non-dominant lineages of the B. pseudomallei population structure. Our protein prediction analysis of all BimABp and major BimC variants revealed that their 3D structures were conserved compared to those of B. pseudomallei K96243. Sixteen representative strains of the most distant BimABp types were tested for plaque formation and the development of polar actin tails in A549 epithelial cells. We found that all isolates retained these functions. These findings enhance our understanding of the prevalence of BimABp and BimC variants and their implications for B. pseudomallei virulence.

Melioidosis is a neglected tropical disease caused by Burkholderia pseudomallei, endemic to Southeast Asia and Northern Australia. Despite its increasing global public health and clinical significance, the molecular epidemiology of melioidosis and genetic diversity of B. pseudomallei in Cambodia remains poorly understood. This study aims to elucidate the genetic diversity and antibiotic susceptibility profiles of B. pseudomallei isolates responsible for melioidosis in humans. For this purpose, 14 clinical isolates cryopreserved at the Medical Biology Laboratory at Institut Pasteur du Cambodge from 2016 to 2020 were subjected to antimicrobial susceptibility testing and Multilocus Sequence Typing (MLST). Phenotypic testing revealed that 92.86% (13/14) of the isolates were sensitive to all tested antibiotics, while one isolate exhibited resistance to trimethoprim-sulfamethoxazole. MLST analysis resolved our isolates into 14 unique Sequence Types (STs), including 10 previously documented in Southeast Asia. Notably, ST1858, ST2064, ST2065, and ST2066 were identified as novel STs, while ST54, ST99, ST211, and ST1359 were reported in Cambodia for the first time in this study. Comparing our MLST data with available sequences on PubMLST (n = 165), our study unveiled a high genetic diversity of B. pseudomallei in Cambodia. The identified STs were closely associated with isolates from other Southeast Asian countries, particularly Thailand, Vietnam, and Malaysia. In conclusion, this study provided insight into the genetic diversity among B. pseudomallei clinical isolates in Cambodia and their close genetic association with Southeast Asian isolates. To further our understanding, a One Health approach, incorporating human, environmental (mainly soil), and animal compartments, is essential to decipher the epidemiology of B. pseudomallei in Cambodia. Author summary: Melioidosis, caused by the soil-dwelling bacterium Burkholderia pseudomallei, is commonly found in regions of Southeast Asia and northern Australia. Despite appropriate antibiotic treatment, it remains a potentially fatal disease. The clinical manifestations are varied, and the lack of laboratory support in Cambodia leads to underreporting. Limited genetic data are available for B. pseudomallei in Cambodia; this study provides new insights into the genetic characteristics of this bacteria and antibiotic susceptibility in the country, benefiting public health and safety. Using multi-locus sequence typing (MLST), we confirm that Cambodian clinical isolates are closely related to the Southeast Asian cluster, particularly those from Thailand, Vietnam, and Malaysia, reflecting the regional endemicity. This study also reveals new sequence types and antibiotic resistance to the trimethoprim/sulfamethoxazole combination. To further our understanding, a One Health approach, incorporating human, environmental (mainly soil), and animal compartments, is essential to decipher the epidemiology of B. pseudomallei in Cambodia. [ABSTRACT FROM AUTHOR]

Burkholderia thailandensis has emerged as a nonpathogenic surrogate for Burkholderia pseudomallei, the causative agent of melioidosis, and an important Gram-negative model bacterium for studying the biosynthesis and regulation of secondary metabolism. We recently reported that subinhibitory concentrations of trimethoprim induce vast changes in both the primary and secondary metabolome of B. thailandensis. In the current work, we show that the folate biosynthetic enzyme FolE2 is permissive under standard growth conditions but essential for B. thailandensis in the presence of subinhibitory doses of trimethoprim. Reasoning that FolE2 may serve as an attractive drug target, we screened for and identified ten inhibitors, including dehydrocostus lactone (DHL), parthenolide, and ß-lapachone, all of which are innocuous individually but form a chemical-synthetic lethal combination with subinhibitory doses of trimethoprim. We show that DHL is a mechanism-based inhibitor of FolE2 and capture the structure of the covalently inhibited enzyme using X-ray crystallography. In vitro, the combination of subinhibitory trimethoprim and DHL is more potent than Bactrim, the current standard of care against melioidosis. Moreover, unlike Bactrim, this combination does not affect the growth of most commensal and beneficial gut bacteria tested, thereby providing a degree of specificity against B. pseudomallei. Our work provides a path for identifying antimicrobial drug targets and for utilizing binary combinations of molecules that form a toxic cocktail based on metabolic idiosyncrasies of specific pathogens. [ABSTRACT FROM AUTHOR]

Background Melioidosis, attributable to the soil-dwelling bacterium Burkholderia pseudomallei , stands as a paramount global health challenge, necessitating extended courses of antibiotics. While murine studies identified the gut microbiota as a modulator of bacterial dissemination during melioidosis, the human intestinal microbiota during melioidosis remains uncharacterized. Here, we characterized gut microbiota composition and antimicrobial resistance (AMR) genes at diagnosis, during treatment, and postdischarge for melioidosis. We hypothesized that the gut microbiota of melioidosis patients would be extensively distorted. Methods In this prospective observational cohort, stool samples of patients with culture-confirmed melioidosis admitted to a tertiary care hospital in India were collected at diagnosis, 14 days after diagnosis, or discharge (whichever occurred first) and at 6 months postinfection. Family members or neighbors served as community controls. The gut microbiota and resistome were profiled by shotgun metagenomic sequencing. Results We longitudinally analyzed the gut microbiota of 70 fecal samples from 28 patients and 16 community controls. At diagnosis, the gut microbiota of patients differed from that of controls, characterized by high abundances of potentially pathogenic bacteria, a loss of butyrate-producing bacteria, and higher levels of AMR genes. Microbiota composition and resistome remained different from community controls at 6 months, driven by total antibiotic exposure. During hospitalization, gut microbiota profiles were associated with secondary Klebsiella pneumoniae infections. Conclusions This first study on gut microbiota composition and resistome in human melioidosis showed extensive disruptions during hospitalization, with limited signs of restoration 6 months postinfection. Given the adverse outcomes linked with microbiome perturbations, limiting microbiota disruptions or using microbiota-restorative therapies (eg, butyrate-producing probiotics) may be beneficial. [ABSTRACT FROM AUTHOR]

Melioidosis is a life-threatening infectious disease caused by the bacterium Burkholderia pseudomallei. Although culture is the gold standard for diagnosing melioidosis, it is time-consuming and delays timely treatment. Non-culture-based diagnostic techniques are interesting alternatives for the rapid detection of melioidosis. This systematic review provides an overview of the performance of antibody-detection tests for melioidosis. A thorough literature search was conducted in two databases to identify relevant studies published until 31 December 2023. Among the 453 studies identified, 29 were included for further analysis. Various antibody-detection methods have been developed, primarily enzyme-linked immunosorbent assays (ELISAs). Recombinant outer membrane protein A-(OmpA)-specific immunoglobulin G (IgG), immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin D (IgD) exhibited the highest accuracy, with a sensitivity of 95.0% and a specificity of 98.0% in ELISA. Furthermore, immunochromatographic testing has emerged as a promising rapid diagnostic test (RDT), with haemolysin co-regulated protein 1 (Hcp1) demonstrating significant accuracy, a sensitivity of 88.3%, and a specificity of 91.6%. Additionally, IgG against Burkholderia invasion protein D (BipD) showed excellent accuracy, with a sensitivity of 100.0% and a specificity of 100.0% in surface plasmon resonance assay. Combining multiple antigens or employing different detection techniques can enhance the accuracy of melioidosis diagnosis. [ABSTRACT FROM AUTHOR]

Therapies that modulate and appropriately direct the immune response are promising candidates for the treatment of infectious diseases. One such candidate therapeutic is DZ13, a short, synthetic, single-stranded DNA molecule. This molecule has enzymatic activity and can modulate the immune response by binding to and degrading the mRNA encoding a key immunoregulatory molecule. Originally developed and entering clinical trials as an anticancer agent, DZ13 has also been evaluated as a treatment for viral infections, and has been shown to provide protection against infection with influenza virus in a mouse model of infection. In this work, we evaluated whether the immunomodulatory properties of DZ13 could provide protection against the potential biothreat pathogen Burkholderia pseudomallei which causes the neglected tropical disease melioidosis. Treatment of mice infected with B. pseudomallei demonstrated that DZ13 did indeed provide excellent protection after only two post-exposure treatments. However, our data indicated that the enzymatic activity contained in DZ13 was not required for protection, with control oligonucleotide treatments lacking activity against the target mRNA equally as protective against B. pseudomallei. We have designed new sequences to study the mechanism of protection further. These novel sequences offer enhanced protection against infection, but are not directly anti-microbial and do not appear to be stimulating the immune system via TLR9 or other key innate immune sensors, despite containing CpG motifs. The molecular mechanism of these novel sequences remains to be elucidated, but the data highlights that these oligonucleotide-sensing pathways are attractive and relevant targets to modulate during bacterial and viral infections. [ABSTRACT FROM AUTHOR]

Introduction: Patients receiving biological and targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) for rheumatological conditions are at an increased risk of serious, potentially life-threatening, infection. However, the incidence, aetiology, and clinical course of serious infection in patients receiving b/tsDMARDs in tropical settings are incompletely defined. Methods: We retrospectively reviewed all patients with rheumatoid arthritis receiving b/tsDMARDs between October 2012 and October 2021, at Cairns Hospital in tropical Australia. The incidence, aetiology, and clinical course of serious infections (those requiring admission to hospital or parenteral antibiotics) were determined. Results: 310 patients had 1468 patient years of b/tsDMARD therapy during the study period; 74/310 (24%) had 147 serious infections translating to an overall risk of 10.0 episodes of serious infection per 100 patient years. The respiratory tract (50/147, 34%) and skin (37/147, 25%) were the most frequently affected sites. A pathogen was identified in 59/147 (40%) episodes and was most commonly Staphylococcus aureus (24/147, 16%). Only 2/147 (1%) were confirmed "tropical infections": 1 case of Burkholderia pseudomallei and 1 case of mixed B. pseudomallei and community-acquired Acinetobacter baumannii infection. Overall, 13/147 (9%) episodes of serious infection required Intensive Care Unit admission (0.9 per 100-patient years of b/tsDMARD therapy) and 4/147 (3%) died from their infection (0.3 per 100-patient years of b/tsDMARD therapy). The burden of comorbidity and co-administration of prednisone were the strongest predictors of death or a requirement for ICU admission. Conclusions: The risk of serious infection in patients taking b/tsDMARDs in tropical Australia is higher than in temperate settings, but this is not explained by an increased incidence of traditional tropical pathogens. [ABSTRACT FROM AUTHOR]

Endemic in over 45 countries globally, recent reports of locally acquired melioidosis in novel geographical areas, such as the Southern US, have highlighted the expanding geographical range of Burkholderia pseudomallei. Climate change and severe weather events have been linked to an increase in cases of melioidosis, which follows environmental exposure to the bacterium. Healthcare professionals should be aware of the possibility of the disease, with its diverse and often delayed presentations, even in areas not previously known to have risk. Over 200 cases of travel-associated melioidosis have been reported in the literature, highlighting the need to consider this disease in non-endemic areas, as diagnostic delays of up to 18 months have been identified. The review updates the global epidemiology of melioidosis, focusing on new geographical areas where cases have been diagnosed and imported cases, unusual clinical presentations and co-infections, and less frequent modes of transmission (laboratory exposures and the risk of acquisition due to imported infected animals and contaminated products). [ABSTRACT FROM AUTHOR]

Pulmonary melioidosis is a severe tropical infection caused by Burkholderia pseudomallei and is associated with high mortality, despite early antibiotic treatment. γδ T cells have been increasingly implicated as drivers of the host neutrophil response during bacterial pneumonia, but their role in pulmonary melioidosis is unknown. Here, we report that in patients with melioidosis, a lower peripheral blood γδ T-cell concentration is associated with higher mortality, even when adjusting for severity of illness. γδ T cells were also enriched in the lung and protected against mortality in a mouse model of pulmonary melioidosis. γδ T-cell deficiency in infected mice induced an early recruitment of neutrophils to the lung, independent of bacterial burden. Subsequently, γδ T-cell deficiency resulted in increased neutrophil-associated inflammation in the lung as well as impaired bacterial clearance. In addition, γδ T cells influenced neutrophil function and subset diversity in the lung after infection. Our results indicate that γδ T cells serve a novel protective role in the lung during severe bacterial pneumonia by regulating excessive neutrophil-associated inflammation. [ABSTRACT FROM AUTHOR]

Background: Although there is a high incidence of hematogenous infections in melioidosis, a tropical infectious disease, there are few systematic analyses of hematogenous melioidosis in imaging articles. A comprehensive clinical and imaging evaluation of hematogenous melioidosis be conducted in order to achieve early diagnosis of the disease. Materials and methods: We conducted an analysis of 111 cases of melioidosis diagnosed by bacteriological culture between August 2001 and September 2022. The analysis focused on observing the main manifestations of chest imaging and clinical data, including nodules, cavities, consolidation, ground glass opacity(GGO), pleural effusion, centrilobular nodules, and temperature, leucocyte count, diabetes, etc. Our study involved univariate and multivariate analyses to identify significant diagnostic variables and risk predictive factors. Results: A total of 71.2% (79/111) of melioidosis cases were caused by hematogenous infection, and the most common organ involved was the lungs (88.5%, 100/113). The incidence of sepsis in patients with lung abnormalities was high (73%, 73/100), and the mortality rate of septic shock was 22% (22/100). Univariate analysis showed that the radiologic signs of blood culture-positive cases were more likely to have bilateral pulmonary and subpleural nodules (p = 0.003), bilateral GGO (p = 0.001), bilateral hydrothorax (p = 0.011). The multivariate analysis revealed a significant improvement in the area under the receiver operating characteristic curve (AUC) when comparing the model that included both clinical and radiologic variables to the model with clinical variables alone. The AUC increased from 0.818 to 0.932 (p = 0.012). The most important variables in the logistic regression with backward elimination were found to be nodule, GGO, and diabetes. Conclusion: The combination of CT features and clinical variables provided a valuable and timely warning for blood borne infectious melioidosis. [ABSTRACT FROM AUTHOR]

Highly pathogenic Burkholderia pseudomallei is the causative agent of melioidosis, a neglected tropical disease endemic in Southeast Asian tropical region. This bacterium encompasses diverse virulence factors which further undergo dynamic gene-expression flux as it transits through distinct environmental niches within the host which may lead to manifestation of differential clinical symptoms. B. pseudomallei, is classified as a Tier 1 select agent in the United States and regarded as a risk group 3 organism in India with the potential to be used as bioweapon. Considering these facts, it is vital to uncover both physiological and genetic heterogeneity of B. pseudomallei, particularly to identify any novel virulence factors that may contribute to pathogenicity. B. pseudomallei strain CM000113 was isolated from a clinical case in India, characterized it for its physiological, biochemical, and prominently genetic traits through WGS. It has a type 2 morphotype with faster doubling time and high biofilm producing capacity as compared to Pseudomonas aeruginosa. The genome size is 7.3 Mbp and it is phylogenetically close to B. pseudomallei strain Mahidol 1106a and Burkholderia mallei Turkey 2. We observed genetic heterogeneity, as key virulence factors that were identified shows sequence dissimilarity with reference strains. Additionally, presence of genomic islands, harbouring two virulence factors, GmhA and GmhB2, associated with pathogenesis indicates possibility of horizontal gene transfer. These results emphasize the need for an extensive study focusing the genome of B. pseudomallei and its associated heterogeneity, to identify molecular biomarkers aiding to develop point-of-care diagnostic kits for early diagnosis of melioidosis. [ABSTRACT FROM AUTHOR]

Melioidosis is caused by Burkholderia pseudomallei, an opportunistic Gramnegative pathogen that inhabits soil and water in tropical and subtropical regions. B. pseudomallei infections often occur following contact with contaminated water or soil or by inhalation of contaminated dust and water droplets. There is limited knowledge about how B. pseudomallei is able to survive in harsh environmental conditions and compete with the microbes that inhabit these niches. Previous research demonstrated that 3-methyl-2-alkylquinolones (MAQs), and their corresponding N-oxides (MAQNOs), are produced by B. pseudomallei and provide a competitive advantage when grown in the presence of Gram-positive bacteria. In this study, 39 Gramnegative environmental bacteria in the Pseudomonadota and Bacteroidota phyla were isolated and characterized. Intriguingly, B. pseudomallei inhibited 71% of bacteria in the phylum Bacteroidota in zone of inhibition and coculture competition assays, but no Pseudomonadota isolates were similarly inhibited. Transposon mutagenesis was utilized to identify B. pseudomallei genes required for the inhibition of Sphingobacterium sp. ST4, a representative member of the Bacteroidota. Three mutations mapped to hmqA-G, the locus encoding 2-alkylquinolone derivatives, and two mutations were identified in scmR, a gene encoding a quorum-sensing controlled LysR-type transcriptional regulator. B. pseudomallei strains with deletion mutations in hmqD and scmR were unable to produce 2-alkylquinolone derivatives or inhibit Bacteroidota isolates in competition assays. RAW264.7 murine macrophage cells were infected with B. pseudomallei 1026b and 1026b ΔhmqD and there was a 94-fold reduction in the number of intracellular 1026b ΔhmqD bacteria relative to 1026b. The 50% lethal dose (LD50) of 1026b and 1026b ΔhmqD in BALB/c mice was determined to be 3 x 105 colony forming units (CFU) and > 1 x 106 CFU, respectively. Taken together, the results indicate that the products of the B. pseudomallei hmqA-G locus are important for intracellular replication in murine macrophages, virulence in a mouse model of melioidosis, and competition with bacteria that utilize naphthoquinones for aerobic respiration. [ABSTRACT FROM AUTHOR]

Background: Dengue is the most re-emergent infection, with approximately 100 million new cases reported annually, yet no effective treatment or vaccine exists. Here, we aim to define the microbial community structure and their functional profiles in the dengue positive patients with varying disease severity. Methodology/Principal findings: Hospital admitted 112 dengue-positive patients blood samples were analyzed by dual RNA-sequencing to simultaneously identify the transcriptionally active microbes (TAMs), their expressed genes and associated pathways. Results highlight that patients with severe dengue exhibited increased microbial diversity and presence of opportunistic species (unique and core) which includes Bacillus cereus, Burkholderia pseudomallei, Streptococcus suis, and Serratia marcescens. The functional profile analysis revealed enriched metabolic pathways such as protein degradation, nucleotide biosynthesis, ion transport, cell shape integrity, and ATP formation in severe cases, indicating the high energy demands and adaptability of these microbes. Conclusion: Our metatranscriptomic approach provides a species-level characterization of blood microbiome composition and reveals a heightened diversity of TAMs in patients with severe dengue, underscoring the need for further research into the role of blood microbiota in disease progression. Comparing the microbial signatures across the severity classes early in the disease offers unique potential for convenient and early diagnosis of dengue infection. Author summary: Dengue poses a significant public health challenge in tropical and subtropical regions. The lack of a specific treatment or broadly effective vaccine highlights the critical need for novel approaches. In this study, we investigated the transcriptionally active microbial species (TAMs) in 112 dengue-positive patients from MAX Hospital in Delhi, India, to identify their correlations with disease severity. RNA-seq analysis revealed an increased abundance of opportunistic TAMs in severe dengue patients, with some species showing significant associations with platelet counts and total leukocyte count (TLC). Our findings underscore the underappreciated importance of the blood microbiome in dengue, particularly the heightened metabolic activity of these opportunistic species in severe cases. This study offers valuable insights for early infection diagnosis for dengue management. The species-level data identified here could pave the way for systematic exploration of microbial involvement in dengue virus (DENV) infections, potentially serving as an indicator for new adjuvant treatment strategies. [ABSTRACT FROM AUTHOR]

Burkholderia pseudomallei (Bpm) is the causative agent of the disease melioidosis. As a facultative intracellular pathogen, Bpm has a complex lifestyle that culminates in cell-to-cell fusion and multinucleated giant cells (MNGCs) formation. The virulence factor responsible for MNGC formation is the type 6 secretion system (T6SS), a contractile nanomachine. MNGC formation is a cell-to-cell spread strategy that allows the bacteria to avoid the extracellular immune system and our previous data highlighted cell death, apoptosis, and inflammation as pathways significantly impacted by T6SS activity. Thusly, we investigated how the T6SS influences these phenotypes within the macrophage and pulmonary models of infection. Here we report that the T6SS is responsible for exacerbating apoptotic cell death during infection in both macrophages and the lungs of infected mice. We also demonstrate that although the T6SS does not influence differential macrophage polarization, the M2 polarization observed is potentially beneficial for Bpm pathogenesis and replication. Finally, we show that the T6SS contributes to the severity of inflammatory nodule formation in the lungs, which might be potentially connected to the amount of apoptosis that is triggered by the bacteria. Author summary: Burkholderia pseudomallei (Bpm) is an intracellular pathogen and is the etiological agent of melioidosis. This neglected tropical disease results in an estimated 89,000 fatalities a year, however, this number is believed to be severely underreported. The complex intracellular lifestyle and host response to infection is poorly understood, basic cell interactions and responses are critical to defense against infection. Bpm utilizes an array of virulence factors to successfully replicate and disseminate cell-to-cell, one of these is the T6SS which is responsible for MNGC formation and cell-to-cell spread. In this work, we characterized how macrophages respond to infection in the presence or absence of the critical T6SS virulence factor. Macrophages are a primary replicative niche for Bpm but how intracellular replication disrupts macrophages response to infection is poorly understood. By understanding macrophage cell death patterns and polarization, we can dissect responses that are triggered by T6SS activity with the expectation of finding exploitable responses for host directed therapies. [ABSTRACT FROM AUTHOR]

Melioidosis, a human infectious disease with a high mortality rate in many tropical countries, is caused by the pathogen Burkholderia pseudomallei (B. pseudomallei). The function of the B. pseudomallei sigma S (RpoS) transcription factor in survival during the stationary growth phase and conditions of oxidative stress is well documented. Besides the rpoS, bioinformatics analysis of B. pseudomallei genome showed the existence of two rpoN genes, named rpoN1 and rpoN2. In this study, by using the mouse macrophage cell line RAW264.7 as a model of infection, the involvement of B. pseudomallei RpoS and RpoN2 in the invasion, intracellular survival leading to the reduction in multinucleated giant cell (MNGC) formation of RAW264.7 cell line were illustrated. We have demonstrated that the MNGC formation of RAW264.7 cell was dependent on a certain number of intracellular bacteria (at least 5 × 104). In addition, the same MNGC formation (15%) observed in RAW264.7 cells infected with either B. pseudomallei wild type with multiplicity of infection (MOI) 2 or RpoN2 mutant (∆rpoN2) with MOI 10 or RpoS mutant (∆rpoS) with MOI 100. The role of B. pseudomallei RpoS and RpoN2 in the regulation of type III secretion system on bipB-bipC gene expression was also illustrated in this study. [ABSTRACT FROM AUTHOR]

Livestock manure treatment technology and composting and its products have been widely used in agricultural soil. However, little was known about the variations in the fate of pathogens and the factors affecting their pathogenic ability during this process, which posed threats to ecological safety and public health globally. This study used a metagenomic approach to profile the behaviors of pathogens during peroxydisulfate composting. Results showed that Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Burkholderia pseudomallei, and Mycobacterium tuberculosis were the main secretors of virulence factors (VFs) in composting system; their abundance and the virulence factor–related genes they carried were better downregulated under the role of peroxydisulfate. In addition, peroxydisulfate composting ensured the lower moisture, weakening the swimming mobility behavior of pathogens through suppressing the abundance of genes associated with flagellar formation, and impaired the communication between pathogens by regulating quorum sensing (QS)– and quorum quenching (QQ)–related genes. Moreover, reduced abundance of resistomes restricted pathogens disseminating infection. In summary, this study provided useful strategies in managing pathogen pathogenic ability during composting based on pathogenic source (pathogens), pathway (VFs), influencing factors (QS/QQ, physicochemical habitats), and resistomes. [ABSTRACT FROM AUTHOR]

Melioidosis, caused by Burkholderia pseudomallei , is a severe infectious disease prevalent in tropical regions such as Southeast Asia and northern Australia, with an increasing incidence in South Asia, particularly India. The disease often goes undiagnosed due to nonspecific symptoms and limited medical awareness. This report presents the case of a 42-year-old male who died from complications following a head injury. An autopsy revealed melioidosis, with B. pseudomallei detected in blood cultures. The patient had a history of fever and loss of consciousness before his fatal incident, indicating a missed diagnosis. This case underscores the importance of considering melioidosis in differential diagnoses, especially in endemic regions, and the critical role of postmortem microbiology in identifying such infections. It highlights the need for heightened clinical awareness, improved diagnostic facilities, and comprehensive postmortem investigations to understand better and manage melioidosis. Enhanced recognition and early intervention could significantly reduce morbidity and mortality associated with this often-overlooked disease. [ABSTRACT FROM AUTHOR]

Burkholderia pseudomallei is the causative agent of the lethal disease melioidosis. This bacterium infects animals and humans and is increasingly resistant to multiple antibiotics. Recently, genes associated with survival of the bacterium in the infected host have been identified. One of these genes, bpsl0741, is annotated as a hypothetical protein of 185 amino acids. Here, recombinant BPSL0741 (rBPSL0741) protein was expressed, purified, verified by mass spectrometry, crystallized and analyzed by X‐ray diffraction. rBPSL0741 was crystallized by vapor diffusion using a reservoir solution consisting of 0.2 M ammonium acetate, 0.1 M sodium acetate trihydrate pH 4.6, 30% PEG 4000. The crystals diffracted to 2.1 Å resolution using an in‐house X‐ray diffractometer and belonged to an orthorhombic space group, with unit‐cell parameters a = 62.92, b = 64.57, c = 89.16 Å. The Matthews coefficient (VM) was calculated to be 2.18 Å3 Da−1, suggesting the presence of two molecules per asymmetric unit and an estimated solvent content of 43.5%. The crystal was deemed to be suitable for further structural studies, which are currently ongoing. [ABSTRACT FROM AUTHOR]

In the United States in 2021, an outbreak of 4 cases of Burkholderia pseudomallei, the etiologic agent of melioidosis and a Tier One Select Agent (potential for deliberate misuse and subsequent harm), resulted in 2 deaths. The causative strain, B. pseudomallei ATS2021, was unintentionally imported into the United States in an aromatherapy spray manufactured in India. We established that ATS2021 represents a virulent strain of B. pseudomallei capable of robust formation of biofilm at physiologic temperatures that may contribute to virulence. By using mouse melioidosis models, we determined median lethal dose estimates and analyzed the bacteriologic and histopathologic characteristics of the organism, particularly the potential neurologic pathogenesis that is probably associated with the bimABm allele identified in B. pseudomallei strain ATS2021. Our data, combined with previous case reports and the identification of endemic B. pseudomallei strains in Mississippi, support the concept that melioidosis is emerging in the United States. [ABSTRACT FROM AUTHOR]

Background Septic melioidosis is associated with high mortality in resource-limited settings. The current study aims to find 28-d all-cause mortality predictors within 24 h of admission in melioidosis patients presenting to an emergency department. Methods This retrospective cohort study (2018–2022) included melioidosis patients divided into two groups based on their primary outcomes (28-d mortality). All the clinically relevant factors significant in univariate analysis were selected for binary logistic regression analysis. Those factors significant in logistic regression analysis were considered independent predictors of mortality. Results Of the 53 patients with melioidosis, the 28-d mortality of melioidosis patients admitted to the emergency department was 51% (n=27). Respiratory involvement, renal dysfunction, haemodynamic instability, elevated aspartate transaminase, elevated activated partial thromboplastin time, elevated CRP, elevated procalcitonin, decreased albumin, decreased absolute neutrophil count, decreased absolute lymphocyte count and use of piperacillin-tazobactam or azithromycin were significant predictors of mortality on univariate analysis. Vasopressor requirement (p=0.03) and low serum albumin level (0.041) at presentation were independent predictors of mortality. Conclusion Vasopressor requirement and low albumin levels at presentation in the emergency department are independent predictors of mortality. There is a need to create awareness among primary care physicians to enable early diagnosis and prompt initiation of treatment. [ABSTRACT FROM AUTHOR]

Background: Melioidosis is a bacterial infection associated with high mortality. The diagnostic approach to this rare disease in Europe is challenging, especially because pulmonary manifestation of melioidosis can mimic pulmonary tuberculosis (TB). Antibiotic therapy of melioidosis consists of an initial intensive phase of 2–8 weeks followed by an eradication therapy of 3–6 months. Case presentation: We present the case of a 46-year-old female patient with pulmonary melioidosis in Germany. The patient showed chronic cough, a pulmonary mass and a cavitary lesion, which led to the initial suspicion of pulmonary TB. Melioidosis was considered due to a long-term stay in Thailand with recurrent exposure to rice fields. Results: Microbiologic results were negative for TB. Histopathology of an endobronchial tumor showed marked chronic granulation tissue and fibrinous inflammation. Melioidosis was diagnosed via polymerase chain reaction by detection of Burkholderia pseudomallei/mallei target from mediastinal lymph-node tissue. Conclusion: This case report emphasizes that melioidosis is an important differential diagnosis in patients with suspected pulmonary tuberculosis and recent travel to South-East Asia. [ABSTRACT FROM AUTHOR]

Background: Melioidosis, an emerging infectious disease that affects both humans and animals, is caused by the soil-dwelling bacterium Burkholderia pseudomallei. It is endemic in South and Southeast Asia, and northern Australia, causing an estimated 165,000 human cases annually worldwide. Human cases have been reported in the French West Indies (Martinique and Guadeloupe) since the 1990s. Conversely, no human cases have been reported in French Guiana, a French territory in South America. Our study aimed to investigate whether B. pseudomallei is locally established in Guadeloupe and French Guiana using animals as a proxy. Methodology/principal findings: Blood samples were collected from different animals from 56 farms in French Guiana (n = 670) and from two goat farms in Les Saintes (n = 31), part of the archipelago of Guadeloupe and tested by enzyme-linked immunosorbent assay (ELISA). In Les Saintes, a serological follow-up was performed, and soil, water and goat rectal swabs were collected and analyzed by culture and PCR. The highest seroprevalence rates (39%) were observed in goats in Les Saintes, followed by horses (24%) and cattle (16%) in French Guiana. In the two goat farms, supplementary analyses detected B. pseudomallei from one goat rectal swab, and a B. pseudomallei strain was isolated from the soil. Conclusions/significance: Our animal serological data suggest the presence of B. pseudomallei in Les Saintes and French Guiana. In Les Saintes, environmental surveys confirmed the endemicity of the bacteria, which is consistent with documented human cases of melioidosis on the island. We did not conduct an environmental survey in French Guiana. Nevertheless, our serological results call for local environmental surveys and a retrospective reassessment of human infections with melioidosis-like symptoms. Author summary: Melioidosis, a disease caused by the environmental bacterium Burkholderia pseudomallei, has historically been described in Southeast Asia and northern Australia. However, recent studies have demonstrated its presence outside these areas, both in the environment and in patients without a history of travel to known endemic areas. In addition, the predicted increase in extreme climatic events in the near future could increase the prevalence of the disease and lead to its emergence in new areas. For these reasons, it is important to identify areas at risk outside of known endemic areas. Hypothesizing that we would have little chance of finding B. pseudomallei through random environmental surveys, we used serological testing to find evidence of past exposure to the bacteria in apparently healthy domestic animals. We identified seropositive animals in Les Saintes and French Guiana. We then searched for the presence of B. pseudomallei in the immediate vicinity of the seropositive animals in Les Saintes, and isolated it in the soil of a goat farm. Our study suggests that domestic animals could be used as sentinels for the detection of melioidosis outside of countries with frequent human cases. [ABSTRACT FROM AUTHOR]

Introduction: Melioidosis may occasionally be encountered in non‐endemic areas and medical imaging is frequently used to identify and characterise sites of disease. The purpose of this study is to describe the spectrum of imaging findings encountered in melioidosis patients treated in the tertiary public hospitals of Perth, Western Australia, between 2002 and 2022. Methods: A database search and electronic medical record review was used to identify cases. Cases were included if they had Burkholderia pseudomallei isolated on culture and if they had at least one diagnostic imaging study performed at a Perth public tertiary hospital. The relevant imaging studies were reviewed, and imaging findings were recorded. Results: Thirty‐six cases were identified. The most common disease manifestation was bacteraemia (72%, 26 cases), followed by pulmonary infection (58%, 21 cases), skin and soft tissue infection (22%, eight cases), prostate abscess (14%, five cases) and septic arthritis (6%, two cases). A previously unreported case of isolated melioid pleural effusion was identified, as was a case of reactivated chronic latent pulmonary melioidosis with an apparent delay of over 20 years between the onset of symptoms and the time of infection. In cases with pulmonary melioidosis, the major lung abnormalities on CT chest could be categorised into one of two distinct patterns: nodular‐predominant (78%) or consolidation‐predominant (22%). Conclusion: Further research is required to assess the utility of the pattern‐based categorisation of lung abnormalities on CT chest seen in the pulmonary melioidosis cases of this series. [ABSTRACT FROM AUTHOR]

Objectives: Melioidosis is an uncommon cause of peritonitis in patients with end-stage renal disease who are receiving continuing peritoneal dialysis. This study aims to investigate the prevalence and outcome of peritoneal dialysis-related peritonitis due to Burkholderia pseudomallei infection. Materials and Methods: A retrospective cohort study of melioidosis infection between 2018 and 2022, peritoneal dialysis-related peritonitis in cases with end-stage renal failure was collected. The patients' demographics, clinical characteristics, and treatments were described. Results: Of the 194 cases diagnosed with peritoneal dialysis-related peritonitis, there were 7 patients (3.6%) with melioidosis peritonitis. The patients' mean age was 51.1 ± 9.44 years old, range of 40–65. Diabetes (5 cases, 71.4%) and hypertension (7 cases, 100%) were the most common co-morbidities. Six cases (85.7%) had fever, 5 (71.4%) had hazy dialysate, and everyone had abdominal pain as clinical signs. Associated septicemia was observed in 5 (71.4%) cases. As part of their antibiotic therapy, meropenem was given to 1 (14.3%) and ceftazidime to 6 (85.7%) cases. Six cases (85.7%) received intravenous antibiotics, whereas 1 (14.3%) case received both intravenous and intraperitoneal routes. The catheters were removed; then, hemodialysis sessions of 5 (71.4%) cases were initiated. Hemodialysis mode was switched permanently in 3 (42.9%) cases and temporarily in one case, thereafter, peritoneal dialysis was resumed. 3 (42.9%) cases died. No significant relations were found about risk factors between survivor and non-survivor group (P < 0.05). Conclusion: Peritoneal dialysis-related peritonitis due to melioidosis is uncommon. However, it may be accompanied by catheter loss and can be lethal if untreated as systemic melioidosis. [ABSTRACT FROM AUTHOR]

The purpose of this report is to provide a comprehensive description of a post-transplant febrile patient's clinical course, complications, surgical procedure, and long-term management including evaluation by 18 F-fluorodeoxyglucose [(18 F)FDG] positron-emission tomography combined with computed tomography (PET/CT). A 35-year-old male, a postrenal transplant patient, developed chronic allograft dysfunction and presented with fever with chills, with suspicion of acute-on-chronic graft dysfunction, but no infective focus localization on chest X-ray, ultrasonography (USG) whole abdomen, or blood culture. Urine microscopy showed 8 to 10 pus cells/high-power field (hpf) and culture showed Klebsiella pneumoniae and Pseudomonas aeruginosa with low colony count. Culture-sensitive antibiotics were prescribed for 2 weeks, and after 3 weeks febrile episodes relapsed, symptoms progressed, and required emergency hospitalization due to acute painful urinary retention. Proteinuria and no growth were noted in urine analysis, serum creatinine was 5.36 mg/dL, and C-reactive protein was 15.7mg/dL, and remaining parameters were unremarkable. [ 18 F]FDG-PET/CT was considered in order to resolve diagnosis, which revealed abnormal heterogeneous tracer uptake in the enlarged prostate with hypodense areas within, suggesting prostatitis with abscess formation and pyelonephritis in the upper pole of the transplant kidney. USG kidney urinary bladder (KUB) correlation confirmed prostatic abscess and transurethral drainage done, and pus culture revealed Burkholderia pseudomallei. Culture-sensitive intravenous meropenem treatment was given for 3 weeks. At 5 weeks, follow-up [ 18 F]FDG-PET/CT showed low metabolic residual prostate uptake, suggesting a good response with residual infection. Thus, intravenous antibiotics was changed to oral antibiotics for another 6 weeks. His symptoms completely resolved at the end of treatment; however, his graft function worsened, with serum creatinine reaching 6 to 7 mg/dL, and eventually, after 8 months he became dialysis dependent. [ABSTRACT FROM AUTHOR]

Efflux pump inhibitors are a potential therapeutic strategy for managing antimicrobial resistance and biofilm formation. This article evaluated the effect of carbonyl cyanide m-chlorophenyl hydrazone (CCCP) on the biofilm growth dynamics and the production of virulence factors by Burkholderia pseudomallei. The effects of CCCP on planktonic, growing, and mature biofilm, interaction with antibacterial drugs, and protease and siderophore production were assessed. CCCP MICs ranged between 128 and 256 µM. The CCCP (128 µM) had a synergic effect with all the antibiotics tested against biofilms. Additionally, CCCP reduced (p <.05) the biomass of biofilm growth and mature biofilms at 128 and 512 µM, respectively. CCCP also decreased (p <.05) protease production by growing (128 µM) and induced (p <.05) siderophore release by planktonic cells (128 µM) growing biofilms (12.8 and 128 µM) and mature biofilms (512 µM). CCCP demonstrates potential as a therapeutic adjuvant for disassembling B. pseudomallei biofilms and enhancing drug penetration. [ABSTRACT FROM AUTHOR]

We report a first case of ceftazidime-resistant pediatric melioidosis involving a previously healthy seven-year-old boy who presented with right lobar pneumonia complicated with a 5-cm lung abscess. Ceftazidime was initiated on Day-6 of admission when Burkholderia pseudomallei (ceftazidime-susceptible, minimum inhibitory concentration [MIC] 1.0 mcg/mL) was isolated from blood. Despite ceftazidime therapy at the recommended dosage, he developed fulminant septic shock and respiratory failure on Day-18 of hospitalization, requiring invasive ventilation, hemodynamic support, and continuous renal replacement therapy. His antibiotic was empirically escalated to meropenem; ceftazidime-resistant B. pseudomallei (MIC 32 mcg/mL) was subsequently isolated from blood and endotracheal secretions. He improved after two weeks of intensive care and was discharged well after two months of hospitalization. Our literature review on ceftazidime-resistant B. pseudomallei infection indicates that acquired resistance is a rare but potentially lethal treatment-related complication. All melioidosis patients should be carefully monitored during treatment with ceftazidime (or other β-lactams) for the development of antimicrobial resistance.

Background: Burkholderia pseudomallei is a gram-negative bacterium widely found in Southeast Asia and northern Australia. This bacterium, which lacks an available vaccine, is the causative agent of melioidosis and has properties that potentially enable its exploitation as a bioweapon. Methods: Polymerase chain reaction assays targeting each of the lipopolysaccharide (LPS) genetic types were used to investigate genotype frequencies in B. pseudomallei populations. Silver staining, gas chromatography-mass spectrometry (GC-MS), and immunofluorescence were used to characterize LPS. Results: In our study, a total of 169 clinical B. pseudomallei isolates were collected from Hainan Province, China between 2004 and 2016. The results showed that LPS genotype A was the predominant type, comprising 91.1% of the samples, compared with only 8.9% of LPS genotype B. The majority of patients were male and were diagnosed with sepsis or pneumonia. Silver staining and GC-MS demonstrated that LPS genotypes A and B exhibited distinct phenotypes and molecular structures. Immunofluorescence tests showed there was no cross-reaction between LPS genotypes A and B. Conclusions: This is the first report on the molecular epidemiology of B. pseudomallei based on O-antigen in China. Tracking the regional distribution of different LPS genotypes offers significant insights relevant to the development and administration of LPS-based vaccines.

Burkholderia pseudomallei biofilm is correlated with pathogenesis, antibiotic resistance, and relapsing cases of melioidosis, leading to challenges in clinical management. There is increasing interest in employing biofilm dispersal agents as adjunctive treatments for biofilm-associated infections. Methionine (Met) has shown promise as an anti-biofilm agent by inducing bacterial DNase production, resulting in the degradation of extracellular DNA (eDNA) and dispersion of bacterial biofilm. In this study, we investigated the impact of 0.05–50 μM D-Met and L-Met on the 24-h established biofilm of a clinical isolate, B. pseudomallei H777. Our findings revealed the ability of D-Met and L-Met to disperse the established biofilm in a non-dose-dependent manner accompanied by eDNA depletion. Real-time PCR analysis further identified an up-regulation of bacterial nuclease genes, including recJ, eddB, nth, xth, and recD, in the presence of 0.05 μM D-Met. Similarly, recJ and eddB in B. pseudomallei were up-regulated in response to the presence of 0.05 μM L-Met. Notably, D-Met enhanced the susceptibility of B. pseudomallei H777 biofilm cells to ceftazidime. Our findings indicate a correlation between methionine supplementation and the up-regulation of nuclease genes, leading to eDNA depletion and the dispersal of preformed B. pseudomallei H777 biofilm. This enhances the susceptibility of biofilm cells to ceftazidime, showing promise in combating biofilm-associated B. pseudomallei infections.

In Malaysia, melioidosis is not a notifiable disease but has a high mortality rate, particularly in diabetic patients. Disseminated melioidosis can be fatal, with 16% to 37% of cases presenting with nonspecific symptoms, complicating early diagnosis. Some patients develop abscesses with or without bacteremia. We present a fatal case of disseminated melioidosis in a diabetic patient with vague initial symptoms. Remarkably, she exhibited low septic parameters, including a normal white blood cell count and low C-reactive protein levels, which masked the severity of the infection and delayed appropriate treatment. The absence of early radiological findings and specific laboratory tests further complicated the diagnostic process. This case underscores the necessity for heightened clinical awareness and the advancement of diagnostic tools, particularly in high-risk populations, to facilitate timely interventions and mitigate fatal outcomes. [ABSTRACT FROM AUTHOR]