Multi-systemic melioidosis.

This editorial is a commentary on the article by Ni et al, which was published in the World Journal of Clinical Cases. The article discusses the diagnostic and therapeutic challenges of melioidosis caused by Burkholderia pseudomallei. The case study highlights a rare instance of multisystemic melioidosis in a female patient who did not have a travel history, emphasizing the significance of recognizing this condition in non-endemic regions. Diagnostic complexities and therapeutic strategies are addressed, emphasizing the need for heightened clinical suspicion, comprehensive evaluation, and multidisciplinary collaboration. The editorial delves into the clinical presentation, diagnostic dilemmas, therapeutic approaches, and their implications for patient care in managing multi-systemic melioidosis.

Massive calvarial melioidosis abscess following minor trauma in rural areas of Thailand.

Background: Melioidosis is uncommon but endemic in Southeast Asia and parts of Northern Australia. Cerebral melioidosis is rare but can be spread through several routes, such as hematogenous spreading or the direct inoculation of organisms from wound contamination with soil. It can cause devastating sequelae if the treatment is delayed. However, with early and adequate treatment, patients can recover and have a good quality of life. Case Description: A 62-year-old diabetic male presented with epilepsy 2 months after a head injury. A computed tomography scan revealed an abscess extending from the subgaleal layer to the subdural with osteomyelitis. A craniotomy was performed to remove the abscess. Melioidosis was identified from pus culture. Intravenous meropenem with Bactrim was started, followed by oral doxycycline and bactrim. The patient recovered with no seizure episodes. This patient showed a rare but straightforward infection from direct inoculation in a wound contaminated with soil. Incubation time could be up to 2 months. The infection originates from previously lacerated scalp tissue and invades the skull, causing osteomyelitis and epidural abscess. Prompt treatment brings a good outcome. In patients with risk factors and a suspicious history, broad-spectrum antibiotics should be initiated after removal of the abscess. Conclusion: Melioidosis is still endemic in Thailand. Doctors should be aware of this organism in patients with high-risk factors or travelers who have just returned from an endemic area. Patients should be treated early with an adequate dose and duration of anti-melioidosis.

Unraveling a Case of Uncommon Shoulder Septic Arthritis Attributed to Burkholderia pseudomallei: Investigating a Mysterious Organism.

Melioidosis is a serious infection caused by Burkholderia pseudomallei, typically found in tropical regions but now being increasingly recognized in areas outside its traditional endemic zones. This case report details the experience of a patient with type 2 diabetes mellitus who presented with unusual symptoms, complicating the diagnostic process. Initial treatment attempts were unsuccessful; however, the use of advanced microbiological methods allowed for the swift identification of the pathogen and led to effective treatment. The report showcases the critical need to include melioidosis in the differential diagnosis of severe infections, especially in patients with preexisting medical conditions or those in and around the endemic areas. It highlights the importance of timely and precise diagnosis, targeted antimicrobial therapy, and continuous monitoring to enhance patient outcomes.

Disseminated melioidosis-challenge to routine antibiotic therapy: a case report.

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.

Shared challenges to the control of complex intracellular neglected pathogens.

The complex intracellular pathogens Mycobacterium tuberculosis, Mycobacterium leprae, Leishmania spp., and Burkholderia pseudomallei, which cause tuberculosis, leprosy, leishmaniasis, and melioidosis respectively, represent major health threats with a significant global burden concentrated in low- and middle-income countries. While these diseases vary in their aetiology, pathology and epidemiology, they share key similarities in the biological and sociodemographic factors influencing their incidence and impact worldwide. In particular, their occurrence in resource-limited settings has important implications for research and development, disease prevalence and associated risk factors, as well as access to diagnostics and therapeutics. In accordance with the vision of the VALIDATE (VAccine deveLopment for complex Intracellular neglecteD pAThogeEns) Network, we consider shared challenges to the effective prevention, diagnosis and treatment of these diseases as shaped by both biological and social factors, illustrating the importance of taking an interdisciplinary approach. We further highlight how a cross-pathogen perspective may provide valuable insights for understanding and addressing challenges to the control of all four pathogens.

Cardiac and mediastinum involvement in Burkholderia thailandensis infection: A case report and literature review.

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.

Leptospirosis and melioidosis coinfection presenting as acute respiratory distress syndrome and osteomyelitis: Case report and systematic review.

INTRODUCTION: 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 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 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 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.

Performance of MALDI-TOF MS, real-time PCR, antigen detection, and automated biochemical testing for the identification of Burkholderia pseudomallei.

Burkholderia pseudomallei is the causative agent of melioidosis, a disease highly endemic to Southeast Asia and northern Australia, though the area of endemicity is expanding. Cases may occur in returning travelers or, rarely, from imported contaminated products. Identification of B. pseudomallei is challenging for laboratories that do not see this organism frequently, and misidentifications by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and automated biochemical testing have been reported. The in vitro diagnostic database for use with the Vitek MS has recently been updated to include B. pseudomallei and we aimed to validate the performance for identification in comparison to automated biochemical testing with the Vitek 2 GN card, quantitative real-time polymerase chain reaction (qPCR) targeting the type III secretion system, and capsular polysaccharide antigen detection using a lateral flow immunoassay (LFA). We tested a "derivation" cohort including geographically diverse B. pseudomallei and a range of closely related Burkholderia species, and a prospective "validation" cohort of B. pseudomallei and B. cepacia complex clinical isolates. MALDI-TOF MS had a sensitivity of 1.0 and specificity of 1.0 for the identification and differentiation of B. pseudomallei from related Burkholderia species when a certainty cutoff of 99.9% was used. In contrast, automated biochemical testing for B. pseudomallei identification had a sensitivity of 0.83 and specificity of 0.88. Both qPCR and LFA correctly identified all B. pseudomallei isolates with no false positives. Due to the high level of accuracy, we have now incorporated MALDI-TOF MS into our laboratory's B. pseudomallei identification workflow.IMPORTANCEBurkholderia pseudomallei causes melioidosis, a disease associated with high morbidity and mortality that disproportionately affects rural areas in Southeast Asia and northern Australia. The known area of endemicity is expanding and now includes the continental United States. Laboratory identification can be challenging which may result in missed or delayed diagnoses and poor patient outcomes. In this study, we compared mass spectrometry using an updated spectral database with multiple other methods for B. pseudomallei identification and found mass spectrometry highly accurate. We have therefore incorporated this fast and cost-effective method into our laboratory's workflow for B. pseudomallei identification.

Virulence of Burkholderia pseudomallei ATS2021 Unintentionally Imported to United States in Aromatherapy Spray.

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.

Clinical and radiological characteristics of mediastinal melioidosis: A four-year retrospective cohort from Sabah, Malaysia.

BACKGROUND: Melioidosis is a potentially fatal tropical infection. Little is known about mediastinal involvement in melioidosis. This study aimed to (a) describe the prevalence and demographics of various morphologies of mediastinal melioidosis, (b) propose a classification for radiological morphologies of mediastinal melioidosis. METHODS: A retrospective cohort study was performed. Case records of consecutive patients with culture-positive melioidosis who underwent computed tomography (CT) thorax from January 1, 2018-February 28, 2022, were reviewed. RESULTS: 486 culture-positive melioidosis patients were identified, of which 70 underwent CT thorax. 41 patients demonstrating mediastinal involvement were included in the final analysis, of which four were mediastinal collections, while the rest were classified into those with necrotic or matted appearances, and subcentimeter and larger than 1 cm. Culture-positivity was proven from blood in 83 % of patients (n = 34), with the remaining from chest wall pus, neck abscess pus, sputum, liver abscess, seminal vesicle, pleural, pericardial and peritoneal fluid. The most commonly associated pulmonary manifestations were consolidation and pleural effusion. Half had diabetes; a quarter had chronic kidney disease, while one had syphilis. Exposure to soil was present in six patients: quarry (n = 1), construction (n = 2), farmer (n = 1), living environment (n = 2). Seven patients succumbed before the end of 6-week intensive phase antibiotic treatment. CONCLUSION: Mediastinal melioidosis is a spectrum with multiple overlapping features consisting of necrosis, matted lymph nodes, multiseptated and non-septated collections. Further studies will elucidate the prognostic implications of mediastinal melioidosis.

An unusual case of primary melioidotic prostatic disease: Misdiagnosed as benign prostatic hyperplasia.

Melioidosis is a fatal infectious disease caused by Burkholderia pseudomallei. Its clinical manifestations are so varied that it has been called a great mimic. The primary melioidotic prostatic disease usually presents as an abscess of the prostate. This is the only documented case misdiagnosed as benign prostatic hyperplasia (BPH) because it does not show as a prostate abscess. The patient was a 66 years old male with a history of hypertension and alcoholism. Symptoms of difficulty urinating and fever had persisted for three days. Laboratory tests of the patient showed a marked increase in inflammatory markers. The first urine culture was performed to isolate Acinetobacter lwoffii, not Burkholderia pseudomallei. And CT showed prostatic hyperplasia with calcification. Thus, the preliminary diagnosis was BPH, urinary tract infection, and pulmonary infection. Cefmenoxime and Piperacillin were given for anti-infective treatment, but both of the effects were not satisfactory. Then, the second urine culture and multiple hemocultures were performed to isolate Burkholderia pseudomallei. The final diagnosis was primary melioidotic prostatic disease, BPH, pulmonary infection, bacteremia and multiple organ damage. The patient was treated with imipenem for two weeks and cured. Trimethoprim-sulfamethoxazole (TMP-SMX) was administered orally for twelve weeks after discharge. Therefore, clinicians need to have an understanding of primary melioidotic prostate disease to avoid misdiagnosis and mistreatment to improve the cure rate and survival rate of patients.

Whitmore's Disease: A Case Report of Melioidosis Triggering Hemophagocytic Lymphohistiocytosis.

Melioidosis is a rare disease caused by Burkholderia pseudomallei, which has recently acquired prominence in India as an emerging pathogen. It is a gram-negative bacteria found in soil. As delayed diagnosis and treatment are linked to increased mortality, early diagnosis is crucial. We present here a unique instance of melioidosis that was made worse by a rare disorder known as hemophagocytic lymphohistiocytosis (HLH), which necessitates early treatment.

Protein expression, purification, crystallization and crystallographic studies of BPSL0741 from Burkholderia pseudomallei.

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 Šresolution 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.

Multi-locus sequence typing and genetic diversity of antibiotic-resistant genes and virulence-associated genes in Burkholderia pseudomallei: Insights from whole genome sequencing of animal and environmental isolates in Thailand.

Burkholderia pseudomallei is a Gram-negative bacillus and the etiological agent of melioidosis in humans and animals. The disease is highly endemic in northern Australia and Southeast Asia. Comprehensive genomic data are essential for understanding the bacteria's dissemination and genetic relationships among strains from different geographical regions. In this study, we conducted antimicrobial susceptibility testing and whole-genome sequencing of 54 B. pseudomallei isolates obtained from environmental and animal sources in southern Thailand between 2011 and 2018. Their genomics were determined of antibiotic-resistant genes (ARGs), virulence-associated genes, mobile genetic elements (MGEs), sequence types (STs), and single nucleotide polymorphisms (SNPs) to evaluate their epidemiological relatedness. Remarkably, all 54 isolates displayed sensitivity to antimicrobial agents typically used for melioidosis treatment. We identified nine distinct sequence types: ST392, ST51, ST409, ST508, ST376, ST1721, ST389, ST395, and ST289. Oxacillinase genes and the resistance nodulation family of efflux pumps (RND) were identified as contributors to antimicrobial resistance. Phylogenetic analysis demonstrated close genetic relations with other strains isolated from Southeast Asia. Furthermore, 172 virulence-associated genes were identified among the isolates, suggesting variations in clinical presentations. These findings underscore the importance of ongoing molecular genetic surveillance of B. pseudomallei for effective healthcare management and reducing melioidosis mortality.

TetR-like regulator BP1026B_II1561 controls aromatic amino acid biosynthesis and intracellular pathogenesis in Burkholderia pseudomallei.

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.

Predictors of mortality in culture-proven Burkholderia pseudomallei infections in a Singapore Tertiary Hospital.

Burkholderia pseudomallei is a pathogen expanding in geographic range. We performed a retrospective study analyzing the clinical, microbiologic features of culture-proven melioidosis, and predictors of mortality based on data from a Singapore tertiary hospital between 2006- 2016. We found ICU admission, bacteremia, and mechanical ventilation to be associated with mortality.

The genetic diversity and evolution analysis of the Hainan melioidosis outbreak strains.

Melioidosis is a zoonotic disease, with its outbreaks being rare and indicative of an unusual concurrence of extreme climate and natural environmental factors. An outbreak of melioidosis cases emerged in Hainan following Typhoon "Dianmu" from October to December 2021, presenting an opportunity to identify the environmental sources of infection for these cases due to its nature as a well-defined point-source cluster. To investigate the relationship between the occurrence of these melioidosis cases and the environment, we extracted the entire genome of 25 clinical strains and conducted MLST typing, followed by whole genome sequencing and analysis of molecular genetic information for four ST46 genotypes from these strains. Phylogenetic and evolutionary relationships between Hainan sequence types (STs) and those found in other endemic regions were analyzed using IslandPath-DIMO, PHASTER, e-BURST, PHYLOViZ, and the maximum likelihood method. Notably, a total of 25 clinical strains were identified, encompassing 12 STs (ST46, ST1105, ST1991, ST30, ST1992, ST50, ST164, ST55, ST70, ST1993, ST1545, and ST58), with ST1991, ST1992, and ST1993 being newly discovered subtypes. PHYLOViZ clustering analysis divided the strains into two groups (A and B), both closely related to the Asian region. Phylogenetic tree analysis further revealed that most of the strains in this study were closely related to those found in Australia and Thailand. Analysis of patient information and visits to their residences suggested that contaminated water sources might be the primary source of infection during this outbreak. Our findings underscore that extreme weather events, such as typhoons, significantly increase the infection rate of B. pseudomallei, along with its genetic diversity, necessitating additional prevention strategies to control these B. pseudomallei infections.

Isolation and characterization of ssDNA aptamers against BipD antigen of Burkholderia pseudomallei.

BACKGROUND: Melioidosis is difficult to diagnose due to its wide range of clinical symptoms. The culture method is time-consuming and less sensitive, emphasizing the importance of rapid and accurate diagnostic tests for melioidosis. Burkholderia invasion protein D (BipD) of Burkholderia pseudomallei is a potential diagnostic biomarker. This study aimed to isolate and characterize single-stranded DNA aptamers that specifically target BipD. METHODS: The recombinant BipD protein was produced, followed by isolation of BipD-specific aptamers using Systematic Evolution of Ligands by EXponential enrichment. The binding affinity and specificity of the selected aptamers were evaluated using Enzyme-Linked Oligonucleotide Assay. RESULTS: The fifth SELEX cycle showed a notable enrichment of recombinant BipD protein-specific aptamers. Sequencing analysis identified two clusters with a total of seventeen distinct aptamers. AptBipD1, AptBipD13, and AptBipD50 were chosen based on their frequency. Among them, AptBipD1 exhibited the highest binding affinity with a Kd value of 1.0 µM for the recombinant BipD protein. Furthermore, AptBipD1 showed significant specificity for B. pseudomallei compared to other tested bacteria. CONCLUSION: AptBipD1 is a promising candidate for further development of reliable, affordable, and efficient point-of-care diagnostic tests for melioidosis.

Multiple liver, splenic and psoas abscesses due to melioidosis: A case report.

Melioidosis is caused by community-acquired gram-negative bacillus Burkholderia pseudomallei which resides in soil and water. It was first described in 1912 in Burma and 1927 in Sri Lanka. Melioidosis presents with non-specific clinical and biochemical findings. Diagnosis is confirmed by the isolation of bacteria in cultures or demonstrating antibody response. Once the diagnosis is made, patients are managed with a course of intravenous antibiotics followed by a long course of oral antibiotics. Even with antibiotic treatments, most patients do not achieve complete recovery which results in chronic disease. Prolonged antibiotic therapy makes patients less compliant with treatment. Here we present a 50-year-old Sri Lankan male with diabetes mellitus presented with low-grade fever and back pain. He was found to have multiple abscesses involving the liver, spleen and left psoas muscle. Initially, he was evaluated for tuberculosis and later only melioidosis was diagnosed. The patient was managed with guided aspiration of abscesses and intravenous antibiotics. Subsequently, the patient defaulted on all treatments. It is important to consider melioidosis as a differential diagnosis in immunocompromised patients presented with multiple abscesses. It is important to maintain a registry for follow-up melioidosis patients to prevent becoming chronic melioidosis patients and to save healthcare costs.