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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.

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]

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]

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: Patients with an active cancer are more likely to develop melioidosis, but the characteristics and clinical course of melioidosis in patients with cancer have not been examined in detail. Trimethoprim/sulfamethoxazole (TMP-SMX) prophylaxis is prescribed to prevent melioidosis in patients receiving immune suppressing anti-cancer therapy in some jurisdictions–and is recommended in national Australian guidelines–however the risks and benefits of this strategy are incompletely defined. Methods: The study took place in Far North Queensland (FNQ) in tropical Australia. The characteristics and clinical course of patients with melioidosis diagnosed in the FNQ region between January 1, 1998, and June 1, 2023, who had–and did not have–an active cancer were compared. We also determined the subsequent incidence of melioidosis in patients receiving immune suppressing anti-cancer therapy in the FNQ region between January 1, 2008, and June 1, 2023, who did–and did not–receive TMP-SMX chemoprophylaxis for Pneumocystis jirovecii infection. Results: An active cancer was present in 47/446 (11%) cases of melioidosis diagnosed between January 1, 1998, and June 1, 2023; there was no association between melioidosis and any cancer type. Patients with melioidosis and cancer were more likely to be older (odds ratio (OR) (95% confidence interval (CI): 1.05 (1.03–1.08) P<0.0001) and immunosuppressed (OR (95% CI): 11.54 (5.41–24.6), p<0.0001) than patients without cancer. Immune suppressing anti-cancer therapy had been prescribed to 17/47 (36%) in the 12 months prior to their diagnosis of melioidosis. Only 10/47 (21%) with cancer and melioidosis in the cohort had received no immune suppressing anti-cancer therapy and had no other risk factors for melioidosis. Twelve months after the diagnosis of melioidosis, 25/47 (53%) were still alive; 9/22 (41%) deaths were due to melioidosis and 13/22 (59%) were due to the underlying cancer. Between 2008 and June 2023, there were 4400 individuals who received myelosuppressive anti-cancer therapy in the FNQ region. There was no significant difference in the incidence of melioidosis between patients who did–and did not–receive TMP-SMX chemoprophylaxis with their myelosuppressive anti-cancer therapy (1/737 (0.15%) versus 16/3663 (0.44%); relative risk (95% confidence interval): 0.31 (0.04–2.34), p = 0.20) and no significant difference in the incidence of fatal melioidosis (0/737 versus 3/3663 (0.08%), p = 0.58). Conclusions: Patients with cancer are predisposed to developing melioidosis and immune suppressing anti-cancer therapy increases this risk further. However, in this region of Australia, there was no significant difference in the subsequent development of melioidosis in patients who did–and did not–receive TMP-SMX chemoprophylaxis during their myelosuppressive anti-cancer therapy. Author summary: In this study from a tertiary hospital in tropical Australia, an active cancer was present in 11% of 446 patients with cultured-confirmed melioidosis, However, no solid organ or haematological cancer diagnosis appeared to be associated with developing the infection. Approximately half of the individuals with cancer who developed melioidosis died within 12 months of their melioidosis diagnosis, however, deaths were more commonly due to their underlying cancer than their melioidosis. Immune suppressing anti-cancer therapy had been prescribed in the prior 12 months in 36% of the individuals with cancer and melioidosis. Trimethoprim-sulfamethoxazole (TMP-SMX) is not prescribed routinely to prevent melioidosis in local patients receiving myelosuppressive anti-cancer therapy, but individuals receiving twice weekly TMP-SMX chemoprophylaxis against Pneumocystis jirovecii pneumonia did not have a statistically lower rate of melioidosis than individuals who did not receive this chemoprophylaxis. Melioidosis was a rare complication of myelosuppressive anti-cancer therapy in the region. Only 16/3663 (0.44%) individuals not receiving TMP-SMX chemoprophylaxis developed melioidosis, and only 3/3663 died from the disease (0.08%). As TMP-SMX has a range of potential side effects–and has the potential to interrupt the delivery of anti-cancer therapy and drive resistance to an important antibiotic–our data do not presently support TMP-SMX prophylaxis for melioidosis in patients receiving anti-cancer therapies in this region of Australia. [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]

Introduction: Melioidosis caused by Burkholderia pseudomallei, often referred to as a great mimicker or escapist, evades not only the immune system, but also all manual identification methods in an under-equipped clinical microbiology laboratory due to its tedious identification process. This is a case report of disseminated melioidosis with septic arthritis, misdiagnosed both clinicoradiologically and microbiologically as disseminated tuberculosis or other bacterial infection. Case history: A middle-aged Asian diabetic male presented with high-grade fever and breathlessness for 4 days along with left knee and ankle swelling for 40 days. Previous hospitalization records revealed growth of pan-sensitive Acinetobacter spp. from ankle and a chest X-ray suspecting tuberculosis for which antibiotic and antitubercular regimen were initiated. After admission, repeated blood cultures and pus culture (ankle and knee joint) confirmed Burkholderia pseudomallei with VITEK-II automated identification system. Recommended therapy was initiated according to revised Darwin's guideline, leading to gradual cure of the patient. Conclusion: Misidentification leads to inadequate treatment, as melioidosis medication is different from other bacterial infections. Here initiation of meropenem- and cotrimoxazole-intensive therapy for 4 weeks, and 6-month eradication phase with cotrimoxazole, resulted in gradual recovery of the patient. It took around 21 days of intensive antibiotic therapy to get bacteriological clearance from blood, which signifies the tenacious nature of this infection. [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: 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]

Melioidosis, an infectious disease caused by Burkholderia pseudomallei, is prevalent in Southeast Asia and Northern Australia, presenting various clinical manifestations from asymptomatic to life-threatening infections. Although primarily affecting the lungs, intra-abdominal viscera, and musculoskeletal system, melioidosis can rarely involve the heart and mediastinum, which pose significant diagnostic and therapeutic challenges. Herein, we present the case of a 53-year-old male farmer who presented with persistent fever and chest pain, progressing to pericarditis and cardiac tamponade. Imaging revealed necrotic mediastinal lymphadenopathy and an enhancing pericardium with pericardial effusion. The patient underwent emergency surgical drainage and was treated with intravenous followed by oral antibiotics. Culture confirmed Burkholderia thailandensis, a closely related but less commonly reported species. This report highlights the complexities of diagnosing and managing B. thailandensis, which can mimic aortic disease, tuberculosis, malignancies, and other inflammatory conditions, especially in endemic areas, emphasizing the need for prompt medical and surgical treatment to improve patient outcomes.

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.

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.

Abstract Introduction Melioidosis caused by Burkholderia pseudomallei, often referred to as a great mimicker or escapist, evades not only the immune system, but also all manual identification methods in an under-equipped clinical microbiology laboratory due to its tedious identification process. This is a case report of disseminated melioidosis with septic arthritis, misdiagnosed both clinicoradiologically and microbiologically as disseminated tuberculosis or other bacterial infection. Case history A middle-aged Asian diabetic male presented with high-grade fever and breathlessness for 4 days along with left knee and ankle swelling for 40 days. Previous hospitalization records revealed growth of pan-sensitive Acinetobacter spp. from ankle and a chest X-ray suspecting tuberculosis for which antibiotic and antitubercular regimen were initiated. After admission, repeated blood cultures and pus culture (ankle and knee joint) confirmed Burkholderia pseudomallei with VITEK-II automated identification system. Recommended therapy was initiated according to revised Darwin’s guideline, leading to gradual cure of the patient. Conclusion Misidentification leads to inadequate treatment, as melioidosis medication is different from other bacterial infections. Here initiation of meropenem- and cotrimoxazole-intensive therapy for 4 weeks, and 6-month eradication phase with cotrimoxazole, resulted in gradual recovery of the patient. It took around 21 days of intensive antibiotic therapy to get bacteriological clearance from blood, which signifies the tenacious nature of this infection.

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.

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]

Burkholderia pseudomallei (Bp) causes the tropical disease melioidosis that afflicts an estimated 165,000 people each year. Bp is a facultative intracellular pathogen that transits through distinct intracellular stages including attachment to host cells, invasion through the endocytic pathway, escape from the endosome, replication in the cytoplasm, generation of protrusions towards neighboring cells, and host cell fusion allowing Bp infection to spread without exiting the intracellular environment. We have identified a TetR-like transcriptional regulator, BP1026B_II1561, that is up-regulated during the late stages of infection as Bp protrudes toward neighboring cells. We have characterized BP1026B_ II1561 and determined that it has a role in pathogenesis. A deletional mutant of BP1026B_II1561 is attenuated in RAW264.7 macrophage and BALB/c mouse models of infection. Using RNA-seq, we found that BP1026B_II1561 controls secondary metabolite biosynthesis, fatty acid degradation, and propanoate metabolism. In addition, we identified that BP1026B_II1561 directly controls expression of an outer membrane porin and genes in the shikimate biosynthetic pathway using ChIP-seq. Transposon mutants of genes within the BP1026B_ II1561 regulon show defects during intracellular replication in RAW264.7 cells confirming the role of this transcriptional regulator and the pathways it controls in pathogenesis. BP1026B_II1561 also up-regulates the majority of the enzymes in shikimate and tryptophan biosynthetic pathways, suggesting their importance for Bp physiology. To investigate this, we tested fluorinated analogs of anthranilate and tryptophan, intermediates and products of the shikimate and tryptophan biosynthetic pathways, respectively, and showed inhibition of Bp growth at nanomolar concentrations. The expression of these pathways by BP1026b_II1561 and during intracellular infection combined with the inhibition of Bp growth by fluorotryptophan/anthranilate highlights these pathways as potential targets for therapeutic intervention against melioidosis. In the present study, we have identified BP1026B_II1561 as a critical transcriptional regulator for Bp pathogenesis and partially characterized its role during host cell infection. [ABSTRACT FROM AUTHOR]

Melioidosis, a severe bacterial illness caused by Burkholderia pseudomallei, is prevalent in most parts of Thailand, including its southern region situated within the Malay Peninsula. Despite a lower reported incidence rate of melioidosis in the South compared to the Northeast, the mortality rate remains persistently high. This study aimed to better understand the epidemiology and investigate the presence of B. pseudomallei in the natural environment of southern Thailand. Using multi-locus sequence typing (MLST), we characterized B. pseudomallei isolates derived from human cases and compared them with previously reported sequence types (STs) from the same region. A total of 263 clinical isolates retrieved from 156 melioidosis patients between 2014 and 2020 were analyzed, revealing 72 distinct STs, with 25 (35%) matching STs from Finkelstein's environmental isolates collected in southern Thailand during 1964–1967. Notably, strains bearing STs 288, 84, 54, 289, and 46 were frequently found among patients. Additionally, we observed strain diversity with multiple STs in 13 of 59 patients, indicating exposure to various B. pseudomallei genotypes in the environmental sources of the infection. Environmental surveys were conducted in Songkhla Province to detect B. pseudomallei in soil and water samples where local patients lived. Of the 2737 soil samples from 208 locations and 244 water samples from diverse sources, 52 (25%) soil sampling locations and 63 (26%) water sources were cultured positive for B. pseudomallei. Positive soil samples were predominantly found in animal farming area and non-agricultural zones like mountains and grasslands, while water samples were frequently positive in waterfalls, streams, and surface runoffs, with only 9% of rice paddies testing positive. Collectively, a significant proportion of recent melioidosis cases in Songkhla Province can be attributed to known B. pseudomallei STs persisting in the environment for at least the past six decades. Further characterization of B. pseudomallei isolates from recent environment surveys is warranted. These findings illuminate the contemporary landscape of B. pseudomallei infections and their environmental prevalence in southern Thailand, contributing to the regional threat assessment in Thailand and Southeast Asia. Author summary: This study conducted a genetic analysis of Burkholderia pseudomallei, the bacterium causing a deadly tropical disease, from 156 patients in southern Thailand during 2014–2020. It found various genotypes, some of which were consistent with the genotypes found in the environment dating back to the 1960s. Extensive testing of soil and water in the region revealed contamination with B. pseudomallei. Areas such as animal farms, mountains, grasslands, and natural water sources e.g., streams and waterfalls, were mostly affected. This finding confirmed that some B. pseudomallei genotypes have had a long-standing presence in the environment, contributing to recent human cases. This study not only enhance our understanding of the spread of melioidosis throughout Southeast Asia but also highlights the importance of ongoing research and monitoring of B. pseudomallei in natural environments to address potential risks associated with the bacterium's persistence. [ABSTRACT FROM AUTHOR]

Introduction: Both leptospirosis and melioidosis are common in tropical and temperate climates and can be acquired by exposure to contaminated water and soil. However, concomitant leptospirosis and melioidosis infection is rarely described in the literature. We report here a case of leptospirosis-melioidosis coinfection and systematically review the literature. Case presentation: A 42-year-old male presented with fever associated with chills and rigor, dull aching pain in the right thigh, myalgia, progressive breathlessness, and dry cough for 10 days. At presentation, he was tachypneic and had tachycardia, and oxygen saturation was 46% in room air. Chest radiography and computed tomography scan showed interstitial involvement. Magnetic resonance imaging for thigh pain revealed right femur osteomyelitis. Leptospira serology was positive, and blood culture grew Burkholderia pseudomallei, confirming the diagnosis of melioidosis. Thus, a diagnosis of presumptive leptospirosis based on modified Faine’s criteria and systemic melioidosis was made. He received doxycycline and intravenous meropenem and improved. Results: We performed a systematic review to understand the spectrum of leptospirosis-melioidosis coinfection. We identified only nine cases of coinfection described in the literature. Only one patient had septic arthritis, and our case is the only one presenting with osteomyelitis. Serology diagnosed leptospirosis, whereas melioidosis was confirmed by blood culture in most patients. The majority of coinfected patients developed some complications, and six patients died. Conclusions: Leptospirosis-melioidosis coinfection is rarely reported in the literature. Physicians should maintain a high index suspicion of leptospirosis-melioidosis coinfection in patients presenting with acute febrile illness following exposure to soil or freshwater, particularly in tropical and endemic regions. [ABSTRACT FROM AUTHOR]

Hemodialysis is a risk factor for Staphylococcus aureus bloodstream infection (SAB). In this single-center study, SAB rates were 56% lower during the monsoonal wet season when patients on hemodialysis receive supervised melioidosis prophylaxis with trimethoprim-sulfamethoxazole. This intervention may reduce SAB rates in high-risk patients; however, further targeted studies are required. [ABSTRACT FROM AUTHOR]

Melioidosis caused by Burkholderia pseudomallei is an infectious disease with a high mortality rate. In acute melioidosis, sepsis is a major cause of death among patients. Once the bacterium enters the bloodstream, immune system dysregulation ensues, leading to cytokine storms. In contrast to B. pseudomallei, a closely related but non-virulent strain B. thailandensis has rarely been reported to cause cytokine storms or death in patients. However, the mechanisms in which the virulent B. pseudomallei causes sepsis are not fully elucidated. It is well-documented that monocytes play an essential role in cytokine production in the bloodstream. The present study, therefore, determined whether there is a difference in the innate immune response to B. pseudomallei and B. thailandensis during infection of primary human monocytes and THP-1 monocytic cells by investigating pyroptosis, an inflammatory death pathway known to play a pivotal role in sepsis. Our results showed that although both bacterial species exhibited a similar ability to invade human monocytes, only B. pseudomallei can significantly increase the release of cytosolic enzyme lactate dehydrogenase (LDH) as well as the increases in caspase-1 and gasdermin D activations in both cell types. The results were consistent with the significant increase in IL-1β and IL-18 production, key cytokines involved in pyroptosis. Interestingly, there was no significant difference in other cytokine secretion, such as IL-1RA, IL-10, IL-12p70, IL-15, IL-8, and IL-23 in cells infected by both bacterial species. Furthermore, we also demonstrated that ROS production played a crucial role in controlling pyroptosis activation during B. pseudomallei infection in primary human monocytes. These findings suggested that pyroptosis induced by B. pseudomallei in the human monocytes may contribute to the pathogenesis of sepsis in acute melioidosis patients. Author summary: Acute melioidosis, caused by B. pseudomallei infection, is considered one of the lethal infectious diseases reported in Southeast Asia and Northern Australia. Infection with this bacterium can lead to a severe systemic inflammatory response or sepsis, which is a major cause of death. The mortality rate of acute melioidosis may reach up to 50%. In contrast, very rare cases were reported from patients infected with B. thailandensis, a non-virulence strain. Although it is well-documented that these two bacteria share genetic similarities and can exhibit similarities in survival and replication inside most murine and human cells, there is very limited information on how only B. pseudomallei can cause sepsis in melioidosis patients, while B. thailandensis dose not. We established an infection model using primary human monocytes to demonstrate that only B. pseudomallei can induce pyroptosis, causing the release of key cytokines that are involved in sepsis. This information may contribute to understanding the mechanisms underlying pathogenesis in acute melioidosis and may guide future treatments. [ABSTRACT FROM AUTHOR]

Melioidosis is a potentially severe disease caused by the gram-negative soil-dwelling bacterium called Burkholderia pseudomallei. The true breadth of the distribution of this tropical pathogen is starting to emerge with environmental and clinical isolates frequently characterized in new countries and regions. Even so, isolates, clinical cases, and genetic data from the continent of Africa remain scant. We previously confirmed the presence of B. pseudomallei in the environment of Ghana, unmasking a new area of endemicity for this pathogen. Here, we describe the genetic characteristics of isolates obtained from that environmental survey. Twenty-one isolates were subjected to whole genome sequencing and found to represent three discrete sequence types (ST), one of which was novel, and designated ST2058. Phylogenetic analysis places this novel isolate within a B. pseudomallei clade that includes genomes derived from the Americas, although it is closely related to a sub-clade that includes isolates from Africa. Importantly, phenotypic characterization demonstrates common features including API 20NE profiles and B. pseudomallei CPS to support existing diagnostics, and susceptibility to standard of care antibiotics often used in the clinical management of melioidosis. These findings add to our knowledge about the presence and distribution of B. pseudomallei in Africa and represent the first published genomes out of Ghana. [ABSTRACT FROM AUTHOR]

Background: Melioidosis, a life-threatening infection caused by the gram negative bacterium Burkholderia pseudomallei, can involve almost any organ. Bone and joint infections (BJI) are a recognised, but incompletely defined, manifestation of melioidosis that are associated with significant morbidity and mortality in resource-limited settings. Methodology/principal findings: We identified all individuals with BJI due to B. pseudomallei managed at Cairns Hospital in tropical Australia between January 1998 and June 2023. The patients' demographics, their clinical findings and their treatment were correlated with their subsequent course. Of 477 culture-confirmed cases of melioidosis managed at the hospital during the study period, 39 (8%) had confirmed BJI; predisposing risk factors for melioidosis were present in 37/39 (95%). However, in multivariable analysis only diabetes mellitus was independently associated with the presence of BJI (odds ratio (95% confidence interval): 4.04 (1.81–9.00), p = 0.001). BJI was frequently only one component of multi-organ involvement: 29/39 (74%) had infection involving other organs and bacteraemia was present in 31/39 (79%). Of the 39 individuals with BJI, 14 (36%) had osteomyelitis, 8 (20%) had septic arthritis and 17 (44%) had both osteomyelitis and septic arthritis; in 32/39 (83%) the lower limb was involved. Surgery was performed in 30/39 (77%). Readmission after the initial hospitalisation was necessary in 11/39 (28%), 5/39 (13%) had disease recrudescence and 3/39 (8%) had relapse; 4/39 (10%) developed pathological fractures. ICU admission was necessary in 11/39 (28%) but all 11 of these patients survived. Only 1/39 (3%) died, 138 days after admission, due to his significant underlying comorbidity. Conclusions: The case-fatality rate from melioidosis BJI in Australia's well-resourced health system is very low. However, recrudescence, relapse and orthopaedic complications are relatively common and emphasise the importance of collaborative multidisciplinary care that includes early surgical review, aggressive source control, prolonged antibiotic therapy, and thorough, extended follow-up. Author summary: Bone and joint infections (BJI) are a recognised and life-threatening manifestation of melioidosis but frequently only one component of multi-organ involvement. Almost all patients with BJI due to Burkholderia pseudomallei have risk factors that predispose them to developing melioidosis, but diabetes appears to be the most closely associated with BJI. The vasculopathy, neuropathy, structural deformity and decreased immunity that is seen in many individuals with diabetes increases their risk of lower limb infection and these factors–combined with greater exposure to B. pseudomallei in the soil and surface water–might explain the lower limb predominance that is seen in many series of melioidosis-related BJI. Patients require early multimodal imaging, appropriate microbiological sampling, early surgical review, prompt source control and an adequate duration of antibiotic therapy–and, in many cases, critical care support–to ensure optimal outcomes. Collaborative, multidisciplinary care reduces the case-fatality rate of melioidosis BJI, but recrudescence, relapse and orthopaedic complications are common in survivors and therefore extended patient follow up is essential. [ABSTRACT FROM AUTHOR]

Melioidosis is an often-fatal neglected tropical disease caused by an environmental bacterium Burkholderia pseudomallei. However, our understanding of the disease-causing bacterial lineages, their dissemination, and adaptive mechanisms remains limited. To address this, we conduct a comprehensive genomic analysis of 1,391 B. pseudomallei isolates collected from nine hospitals in northeast Thailand between 2015 and 2018, and contemporaneous isolates from neighbouring countries, representing the most densely sampled collection to date. Our study identifies three dominant lineages, each with unique gene sets potentially enhancing bacterial fitness in the environment. We find that recombination drives lineage-specific gene flow. Transcriptome analyses of representative clinical isolates from each dominant lineage reveal increased expression of lineage-specific genes under environmental conditions in two out of three lineages. This underscores the potential importance of environmental persistence for these dominant lineages. The study also highlights the influence of environmental factors such as terrain slope, altitude, and river direction on the geographical dispersal of B. pseudomallei. Collectively, our findings suggest that environmental persistence may play a role in facilitating the spread of B. pseudomallei, and as a prerequisite for exposure and infection, thereby providing useful insights for informing melioidosis prevention and control strategies. An environmental bacterium, Burkholderia pseudomallei causes melioidosis, a fatal infection. A study from NE Thailand identifies that dominant lineages carry specific gene sets enhancing environmental persistence. [ABSTRACT FROM AUTHOR]

Burkholderia pseudomallei , an environmental saprophyte, causes an infection that results in melioidosis. A high case-fatality rate is linked to it. Melioidosis is becoming an increasingly global infection. It can present a wide spectrum of manifestations and can affect any part of the human being. The head-and-neck region is a major site of melioidosis infection. Melioidosis in the head-and-neck region is a potentially life-threatening infection. Careful clinical correlation and proper evaluation are needed to establish an early diagnosis of melioidosis. Early diagnosis and prompt treatment are very required. A high index of suspicion in susceptible patients should prompt assessment for melioidosis. The awareness of melioidosis and its clinical manifestations with early diagnosis are needed to avoid failure of treatment which may result in high morbidity and mortality. As melioidosis in the head-and-neck region is not so common, there is very less information available. Therefore, a review article on melioidosis in the head-and-neck region is written with consideration of epidemiology, aetiopathology, clinical manifestations, diagnosis, treatment and prognosis. [ABSTRACT FROM AUTHOR]

Objective: Unique metabolic requirements accompany the development and functional fates of immune cells. How cellular metabolism is important in natural killer (NK) cells and their memory‐like differentiation in bacterial infections remains elusive. Methods: Here, we utilise our established NK cell memory assay to investigate the metabolic requirement for memory‐like NK cell formation and function in response to the Gram‐negative intracellular bacteria Burkholderia pseudomallei (BP), the causative agent of melioidosis. Results: We demonstrate that CD160+ memory‐like NK cells upon BP stimulation upregulate glucose and amino acid transporters in a cohort of recovered melioidosis patients which is maintained at least 3‐month post‐hospital admission. Using an in vitro assay, human BP‐specific CD160+ memory‐like NK cells show metabolic priming including increased expression of glucose and amino acid transporters with elevated glucose uptake, increased mTOR activation and mitochondrial membrane potential upon BP re‐stimulation. Antigen‐specific and cytokine‐induced IFN‐γ production of this memory‐like NK cell subset are highly dependent on oxidative phosphorylation (OXPHOS) with some dependency on glycolysis, whereas the formation of CD160+ memory‐like NK cells in vitro is dependent on fatty acid oxidation and OXPHOS and further increased by metformin. Conclusion: This study reveals the link between metabolism and cellular function of memory‐like NK cells, which can be exploited for vaccine design and for monitoring protection against Gram‐negative bacterial infection. [ABSTRACT FROM AUTHOR]

Background: Burkholderia pseudomallei, an environmental saprophyte bacterium, causes melioidosis in humans and animals. It was first discovered in Iran between 1967 and 1976 in small ruminants, equines, environments and humans. No subsequent studies have been conducted to determine the existence and prevalence of this pathogen in the country. Objectives: The present study aims to monitor the presence of B. pseudomallei in the ruminant population of the Golestan province of Iran, which largely depends on pastures. The ruminants can serve as sentinels to indicate the presence of the bacteria in the environment and its potential impact on human health in the One Health triad. Methods: Liver and lung abscesses from domestic sheep, cattle and goats in three industrial and three conventional slaughterhouses were sampled and analysed using 23S ribosomal DNA polymerase chain reaction (rDNA PCR) with primers CVMP 23‐1 and CVP‐23‐2 for B. pseudomallei, Burkholderia cepacia and Burkholderia vietnamiensis, as well as B. pseudomallei–specific TTS1 real‐time PCR, along with microbiological and biochemical assays. Results: Out of the 97 animals sampled, only 14 (15%) tested positive for 23S rDNA PCR. However, the follow‐up evaluation using TTS1 real‐time PCR and microbiological and biochemical assays did not confirm the presence of B. pseudomallei in the samples. Conclusions: Although B. pseudomallei was not detected in the current survey, conducting abattoir‐based surveillance of ruminants is a cost‐effective One Health approach to monitor pathogenic Burkholderia. Developing standards of clinical and laboratory good practices for Burkholderia infections is crucial for One Health surveillance. [ABSTRACT FROM AUTHOR]

Background: In Malaysia, the mortality from melioidosis infection was reported to be higher than in other infectious diseases. The research on melioidosis is still limited in Malaysia but slightly increasing. Objectives: The objective of the study was to give an overview of the study designs, statistical methods, and comparison of research in identifying the predictors of melioidosis mortality in Malaysia between January 2010 to December 2021. Data sources: Pubmed/Medline. Study eligibility criteria: Original English-language articles were abstracted. The articles that identified the predictors of melioidosis from mortality in Malaysia only included. Letters to the editor, editorials, reviews, systematic reviews, meta-analysis, case reports, and any other ineligible articles were excluded. Results: A total of eight studies were identified related to predictors of melioidosis mortality in Malaysia. From the selected articles, 87.5% were retrospectively collected. Five out of eight articles (62.5%) used the logistic regression in identifying the predictors of melioidosis mortality. Only one (12.5%) used advanced survival analysis methods of Cox regression analysis. Another 25.0% used Chi-square test. Conclusions: Logistic regression methods remain the most common methods of analysis in publications on predictors of melioidosis mortality in Malaysia while retrospective research designs are preferred. There is a limitation of research in predictors of melioidosis mortality and the use of advanced statistical techniques reported using the melioidosis data in Malaysia. More published research on melioidosis will provide input to the clinicians on a more detailed understanding of how to improve the diagnosis of melioidosis and the prognosis factors of this disease. [ABSTRACT FROM AUTHOR]

Background: Burkholderia pseudomallei, the causative agent of melioidosis, is highly genetically recombinant, resulting in significant genomic diversity. Multiple virulence factors have been associated with specific disease presentations. To date, there are limited data relating to genomic diversity and virulence factors associated with melioidosis cases in North Queensland, Australia. Aim: To describe the genetic diversity of B. pseudomallei and identify virulence factors associated with clinical risk factors and patient outcomes. Methods: Whole genome sequencing of clinical isolates was performed and analysed with clinical data obtained from a retrospective melioidosis cohort study. Results: Fifty-nine distinct sequence types (STs) were identified from the 128 clinical isolates. Six STs comprised 64/128 (50%) isolates. Novel STs accounted for 38/59 (64%) STs, with ST TSV-13 as the most prevalent (n = 7), and were less likely to possess an LPS A genotype or YLF gene cluster (p < 0.001). These isolates were most likely to be found outside the inner city (aOR: 4.0, 95% CI: 1.7–9.0, p = 0.001). ST TSV-13 was associated with increased mortality (aOR: 6.1, 95% CI: 1.2–30.9, p = 0.03). Patients with a history of alcohol excess were less likely to be infected by fhaB3 (aOR 0.2, 95% CI: 0.1–0.7, p = 0.01) or YLF (aOR: 0.4, 95% CI: 0.2–0.9, p = 0.04) positive isolates. Conclusions: There are a significant number of novel sequence types in Townsville, Australia. An emerging novel ST appears to have an association with geographic location and mortality. Ongoing investigation is required to further understand the impact of this ST on the Townsville region. [ABSTRACT FROM AUTHOR]

Melioidosis is a tropical infection caused by the intracellular pathogen Burkholderia pseudomallei, an underreported and emerging global threat. As melioidosis-associated mortality is frequently high despite antibiotics, novel management strategies are critically needed. Therefore, we sought to determine whether functional changes in the host innate and adaptive immune responses are induced during acute melioidosis and are associated with outcome. Using a unique whole blood stimulation assay developed for use in resource-limited settings, we examined induced cellular functional and phenotypic changes in a cohort of patients with bacteremic melioidosis prospectively enrolled within 24 h of positive blood culture and followed for 28 days. Compared to healthy controls, melioidosis survivors generated an IL-17 response mediated by Th17 cells and terminally-differentiated effector memory CD8+ T cells (P

Melioidosis infecting a periurethral diverticulum and behaving as an abscess is a rare complication. A 76-year-old woman presented with pelvic pain, dysuria and urinary frequency. CT identified a large periurethral cystic collection and melioidosis was cultured in her urine. Cystoscopy revealed communication between urethra and diverticulum, requiring multiple transvaginal aspirations for re-accumulation and relapsing symptoms. No risk factors for melioidosis were identified, and was likely that isolated urinary infection is due to her urinary tract pathology. This challenging case with a rare pathogen highlights management and source control of melioidosis may need to adapt to anatomical variations promoting abscess reformation.

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 immuno-regulatory molecule. Originally developed and entering clinical trials as an anti-cancer 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 immuno-modulatory 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.

Background: Melioidosis, an infectious disease caused by Burkholderia pseudomallei, is endemic in tropical countries. In nonendemic areas, the disease is rarely suspected because of varying clinical presentations and only a few attempts are made to isolate the pathogen. Many cases are left underdiagnosed or underreported in geographical areas where the disease is not endemic. This study aimed to analyze the clinical presentations, comorbidities, and antibiotic susceptibility patterns in patients with melioidosis in a tertiary care center. Materials and Methods: A retrospective study was done on culture-confirmed melioidosis patients admitted to a tertiary care center, from January 2015 to December 2022. Relevant information on clinical presentations, mortality rate, comorbidities, and antibiogram was collected from hospital medical records. Results: A total of 73 culture-confirmed cases of melioidosis were included in the study. Common clinical presentations were pneumonia (n = 35, 47.9%), septicemia (n = 13, 17.8%), and deep abscesses (n = 9, 12.3%). The mortality rate from melioidosis was 15.1% (n = 11). No significant difference was found in the mortality rate between pneumonia and septicemia groups (P = 0.716). Diabetes mellitus (DM) was the major comorbidity detected (n = 56, 76.7%). Isolates were susceptible to ceftazidime (n = 71, 97.3%), meropenem (n = 71, 97.3%), and co-trimoxazole (n = 60, 82.2%). Conclusions: Common clinical presentations of melioidosis in our setting were pneumonia and septicemia. DM was the major comorbidity. Nearly one in six patients died. Ceftazidime and meropenem were the effective antibiotics. These findings may help physicians to make an early microbiological diagnosis which is essential to reduce mortality.

Abstract Objective Burkholderia pseudomallei, the etiological cause of melioidosis, is a soil saprophyte endemic in South-East Asia, where it constitutes a public health concern of high-priority. Melioidosis cases are sporadically identified in nonendemic areas, usually associated with travelers or import of goods from endemic regions. Due to extensive intercontinental traveling and the anticipated climate change-associated alterations of the soil bacterial flora, there is an increasing concern for inadvertent establishment of novel endemic areas, which may expand the global burden of melioidosis. Rapid diagnosis, isolation and characterization of B. pseudomallei isolates is therefore of utmost importance particularly in non-endemic locations. Data description We report the genome sequences of two novel clinical isolates (MWH2021 and MST2022) of B. pseudomallei identified in distinct acute cases of melioidosis diagnosed in two individuals arriving to Israel from India and Thailand, respectively. The data includes preliminary genetic analysis of the genomes determining their phylogenetic classification in rapport to the genomes of 131 B. pseudomallei strains documented in the NCBI database. Inspection of the genomic data revealed the presence or absence of loci encoding for several documented virulence determinants involved in the molecular pathogenesis of melioidosis. Virulence analysis in murine models of acute or chronic melioidosis established that both strains belong to the highly virulent class of B. pseudomalleii.

Abstract Background Melioidosis, caused by the category B biothreat agent Burkholderia pseudomallei, is a disease with a high mortality rate and requires an immediate culture-independent diagnosis for effective disease management. In this study, we developed a highly sensitive qPCR assay for specific detection of Burkholderia pseudomallei and melioidosis disease diagnosis based on a novel target sequence. Methods An extensive in-silico analysis was done to identify a novel and highly conserved sequence for developing a qPCR assay. The specificity of the developed assay was analyzed with 65 different bacterial cultures, and the analytical sensitivity of the assay was determined with the purified genomic DNA of B. pseudomallei. The applicability of the assay for B. pseudomallei detection in clinical and environmental matrices was evaluated by spiking B. pseudomallei cells in the blood, urine, soil, and water along with suitable internal controls. Results A novel 85-nucleotide-long sequence was identified using in-silico tools and employed for the development of the highly sensitive and specific quantitative real-time PCR assay S664. The assay S664 was found to be highly specific when evaluated with 65 different bacterial cultures related and non-related to B. pseudomallei. The assay was found to be highly sensitive, with a detection limit of 3 B. pseudomallei genome equivalent copies per qPCR reaction. The detection limit in clinical matrices was found to be 5 × 102 CFU/mL for both human blood and urine. In environmental matrices, the detection limit was found to be 5 × 101 CFU/mL of river water and 2 × 103 CFU/gm of paddy field soil. Conclusions The findings of the present study suggest that the developed assay S664 along with suitable internal controls has a huge diagnostic potential and can be successfully employed for specific, sensitive, and rapid molecular detection of B. pseudomallei in various clinical and environmental matrices.

We review the discovery of the tropical infectious disease melioidosis by Alfred Whitmore, a pathologist from England, and his assistant from India, C.S. Krishnaswami. We discuss how the subsequent disappearance of melioidosis from the medical literature of Burma holds parallels with the current neglect and under recognition of the disease. We urge global and national public health authorities to add melioidosis to existing neglected tropical diseases surveillance systems.

In September 2021, a total of 25 patients diagnosed with COVID-19 developed acute melioidosis after (median 7 days) admission to a COVID-19 field hospital in Thailand. Eight nonpotable tap water samples and 6 soil samples were culture-positive for Burkholderia pseudomallei. Genomic analysis suggested contaminated tap water as the likely cause of illness.

The article presents a case study of a 73-year-old man presented with recurrent fever and liver lesions. It is reported that initially, he developed fever, cough, and fatigue, which were treated empirically as pneumonia. It is further reported that subsequent imaging revealed scattered solid pulmonary nodules, hepatic hemangiomas, and subcentimeter hepatic hypodensities.

The reader will come to appreciate that: • Infection occurs through percutaneous inoculation or inhalation with contaminated soil and water. • Diagnosis of melioidosis can be difficult because of its diverse presentation. • Melioidosis is increasingly being diagnosed around the world. • Greater consideration for melioidosis in protracted or atypical pneumonia is warranted regardless of location. Melioidosis is a tropical infectious disease caused by the saprophytic gram-negative bacterium Burkholderia pseudomallei. Despite the infection being endemic in southeast Asia and northern Australia, the broad clinical presentations and diagnostic difficulties limit its early detection, particularly in children. Melioidosis more commonly affects the immunocompromised and adults. Melioidosis is increasingly being diagnosed around the world and whole-genome sequencing indicates that these cases are not linked with travel to endemic areas. Research has concentrated on the adult population with limited experience reported in the care of this uncommon, but potentially fatal condition in children presenting with bacteraemia and pneumonia. [ABSTRACT FROM AUTHOR]

Melioidosis is a bacterial infection caused by Burkholderia pseudomallei, that is common in tropical and subtropical countries including Southeast Asia and Northern Australia. The magnitude of undiagnosed and untreated melioidosis across the country remains unclear. Given its proximity to regions with high infection rates, Riau Province on Sumatera Island is anticipated to have endemic melioidosis. This study reports retrospectively collected data on 68 culture-confirmed melioidosis cases from two hospitals in Riau Province between January 1, 2009, and December 31, 2021, with full clinical data available on 41 cases. We also describe whole genome sequencing and genotypic analysis of six isolates of B. pseudomallei. The mean age of the melioidosis patients was 49.1 (SD 11.5) years, 85% were male and the most common risk factor was diabetes mellitus (78%). Pulmonary infection was the most common presentation (39%), and overall mortality was 41%. Lung as a focal infection (aOR: 6.43; 95% CI: 1.13–36.59, p = 0.036) and bacteremia (aOR: 15.21; 95% CI: 2.59–89.31, p = 0.003) were significantly associated with death. Multilocus sequence typing analysis conducted on six B.pseudomallei genomes identified three sequence types (STs), namely novel ST1794 (n = 3), ST46 (n = 2), and ST289 (n = 1). A phylogenetic tree of Riau B. pseudomallei whole genome sequences with a global dataset of genomes clearly distinguished the genomes of B. pseudomallei in Indonesia from the ancestral Australian clade and classified them within the Asian clade. This study expands the known presence of B. pseudomallei within Indonesia and confirms that Indonesian B. pseudomallei are genetically linked to those in the rest of Southeast Asia. It is anticipated that melioidosis will be found in other locations across Indonesia as laboratory capacities improve and standardized protocols for detecting and confirming suspected cases of melioidosis are more widely implemented. Author summary: Melioidosis is a disease caused by the bacterium Burkholderia pseudomallei. This disease can affect various organs such as the lungs, skin and soft tissues, central nervous system, internal organs, and others. The clinical manifestations vary, and the lack of laboratory examination support in some countries leads to underreporting of the disease. This also results in a varied death rate, ranging from 10–40% and even higher in some countries. The disease is endemic in the Southeast Asian region and northern Australia and is increasingly recognised in other tropical and sub-tropical locations globally. Indonesia has reported over 100 cases from at least 5 diverse regions. One province in Indonesia, Riau, located on the island of Sumatera bordering Malaysia, has been experiencing a relatively high number of melioidosis cases. This study reports melioidosis cases obtained from two referral hospitals in the province of Riau. The research explores the characteristics of patients, clinical manifestations, and outcomes in these cases. Additionally, the study analyzes factors influencing mortality from melioidosis in Riau. Phylogenetic analysis of six isolates of B. pseudomallei determined that B. pseudomallei in the province of Riau, Indonesia is genetically linked to those from neighbouring countries in Southeast Asia. [ABSTRACT FROM AUTHOR]