Pseudomallei Research Articles

Vitamin D (1α,25(OH)2D3) supplementation minimized multinucleated giant cells formation and inflammatory response during Burkholderia pseudomallei infection in human lung epithelial cells.

Melioidosis is an infectious disease with high mortality rates in human, caused by the bacterium Burkholderia pseudomallei. As an intracellular pathogen, B. pseudomallei can escape from the phagosome and induce multinucleated giant cells (MNGCs) formation resulting in antibiotic resistance and immune evasion. A novel strategy to modulate host response against B. pseudomallei pathogenesis is required. In this study, an active metabolite of vitamin D3 (1α,25-dihydroxyvitamin D3 or 1α,25(OH)2D3) was selected to interrupt pathogenesis of B. pseudomallei in a human lung epithelium cell line, A549. The results demonstrated that pretreatment with 10-6 M 1α,25(OH)2D3 could reduce B. pseudomallei internalization to A549 cells at 4 h post infection (P < 0.05). Interestingly, the presence of 1α,25(OH)2D3 gradually reduced MNGC formation at 8, 10 and 12 h compared to that of the untreated cells (P < 0.05). Furthermore, pretreatment with 10-6 M 1α,25(OH)2D3 considerably increased hCAP-18/LL-37 mRNA expression (P < 0.001). Additionally, pro-inflammatory cytokines, including MIF, PAI-1, IL-18, CXCL1, CXCL12 and IL-8, were statistically decreased (P < 0.05) in 10-6 M 1α,25(OH)2D3-pretreated A549 cells by 12 h post-infection. Taken together, this study indicates that pretreatment with 10-6 M 1α,25(OH)2D3 has the potential to reduce the internalization of B. pseudomallei into host cells, decrease MNGC formation and modulate host response during B. pseudomallei infection by minimizing the excessive inflammatory response. Therefore, 1α,25(OH)2D3 supplement may provide an effective supportive treatment for melioidosis patients to combat B. pseudomallei infection and reduce inflammation in these patients.

Synthesis of Trimethyl Chitosan Nanoparticles Containing Recombinant BLF1-stxB Protein of Burkholderia Pseudomallei and Evaluation of its Immunogenicity in Mice

Synthesis of Trimethyl Chitosan Nanoparticles Containing Recombinant BLF1-stxB Protein of Burkholderia Pseudomallei and Evaluation of its Immunogenicity in Mice

DNase I and chitosan enhance efficacy of ceftazidime to eradicate Burkholderia pseudomallei biofilm cells

Biofilm-associated Burkholderia pseudomallei infection contributes to antibiotic resistance and relapse of melioidosis. Burkholderia pseudomallei biofilm matrix contains extracellular DNA (eDNA) that is crucial for biofilm establishment. However, the contribution of eDNA to antibiotic resistance by B. pseudomallei remains unclear. In this study, we first demonstrated in vitro that DNase I with the administration of ceftazidime (CAZ) at 24 h considerably inhibited the 2-day biofilm formation and reduced the number of viable biofilm cells of clinical B. pseudomallei isolates compared to biofilm treated with CAZ alone. A 3–4 log reduction in numbers of viable cells embedded in the 2-day biofilm was observed when CAZ was combined with DNase I. Confocal laser-scanning microscope visualization emphasized the competence of DNase I followed by CAZ supplementation to significantly limit B. pseudomallei biofilm development and to eradicate viable embedded B. pseudomallei biofilm cells. Furthermore, DNase I supplemented with chitosan (CS) linked with CAZ (CS/CAZ) significantly eradicated shedding planktonic and biofilm cells. These findings indicated that DNase I effectively degraded eDNA leading to biofilm inhibition and dispersion, subsequently allowing CAZ and CS/CAZ to eradicate both shedding planktonic and embedded biofilm cells. These findings provide efficient strategies to interrupt biofilm formation and improve antibiotic susceptibility of biofilm-associated infections.

Burkholderia pseudomallei in soil and natural water bodies in rural Sri Lanka: A hidden threat to public health.

Burkholderia pseudomallei is the causative agent of the potentially fatal infection, melioidosis. This study provides the first evidence for the presence of B. pseudomallei in soil and water in Sri Lanka. Targeted sampling of soil and natural water sources was done between November 2019 and October 2020 over eight field visits encompassing the neighborhood of 28 culture and/or antibody-positive melioidosis patients in northwestern, western and southern Sri Lanka. A total of eight environmental isolates of B. pseudomallei (BPs-env1 to BPs-env8) were cultured from 116 soil and 117 natural water samples collected from 72 locations. The presence of B. pseudomallei in soil and natural water in these areas poses a risk of melioidosis for populations cultivating crops in such soils and using untreated water from these sources for drinking, bathing, and other domestic purposes. Identifying sites positive for B. pseudomallei may help to mitigate risk by raising public awareness of contaminated environmental sources and allowing soil and water remediation.

Acute management of pneumonia in adult patients.

Acute management of pneumonia in adult patients.

Effects of Toxin-Antitoxin System HicAB on Biofilm Formation by Extraintestinal Pathogenic E. coli

The type II toxin-antitoxin (T-A) HicAB system is abundant in several bacteria and archaea, such as Escherichia coli, Burkholderia Pseudomallei, Yersinia pestis, Pseudomonas aeruginosa, and Streptococcus pneumoniae. This system engages in stress response, virulence, and bacterial persistence. This study showed that the biofilm-forming ability of the hicAB deletion mutant was significantly decreased to moderate ability compared to the extra-intestinal pathogenic Escherichia coli (ExPEC) parent strain and the complemented strain, which are strong biofilm producers. Congo red assay showed that the hicAB mutant maintained the ability to form curli fimbriae. Using RNA-seq and comparative real-time quantitative RT-PCR, we observed the difference in gene expression between the hicAB mutant and the parent strain, which was associated with biofilm formation. Our data indicate that the HicAB type II T-A system has a key role in biofilm formation by ExPEC, which may be associated with outer membrane protein (OMP) gene expression. Collectively, our results indicate that the hicAB type II T-A system is involved in ExPEC biofilm formation.

Genomics and structural insight into the masking of gentamicin-resistance in clinical Burkholderia pseudomallei strain VB29710 from India

The present study reported a rare gentamicin-susceptible β-lactamase (PenA, OXA-57) expressing clinical Burkholderia pseudomallei isolate VB29710 from India. Whole-genome sequencing and structural analyses revealed the insertion of R962 and L963 into AmrB, the transmembrane-protein of the AmrAB-OprA efflux-pump that affected aminoglycoside-efflux through local alterations in backbone conformation.

Decontamination efficacy of common liquid disinfectants against non-spore-forming biological agents in soil matrices.

The purpose of this study was to evaluate decontamination efficacy, within three soil types, against Yersinia pestis, Burkholderia pseudomallei, and the Venezuelan Equine Encephalitis virus (VEEV). One of three liquid disinfectants (dilute bleach, Virkon-S or Klozur One) was added to three soil types (sand, loam, or clay) and allowed contact for four pre-spike durations: 0, 15, 30 and 60 min. Y. pestis, B. pseudomallei, or VEEV was then spiked into the soil (10 microliters or approx. 1 × 107 CFU or PFU into 1g soil) and decontamination efficacy assessed at post-spike contact times of 10 or 60 min at ambient environmental conditions. Across all soil types, sandy soil resulted in the least quenching to all three disinfectants tested as shown by sustained decontamination efficacy across all pre-spike and post-spike timepoints. Clay and loam soil types exhibited quenching effects on the hypochlorite and peroxygen based disinfectants (dilute bleach and Virkon S) and in general resulted in decreased efficacy with increased pre-spike contact time. The sodium persulfate (Klozur One) performance was the most consistent across all soil types and pre-spike contact times, resulting in greater efficacy with increased post-spike time. Liquid disinfectants can provide high levels of decontamination in soil for both viral and non-spore-forming bacterial select agents. Hypochlorite and peroxygen based disinfectants used in soils containing higher organic content (loam or clay) may require extended contact times or re-application of liquid disinfectant, in as little as 15 min of application, to achieve a 6-log reduction. These results provide information for the performance of three disinfectants in soil against non-spore-forming select agents. These data may aid response decision makers following a biological contamination incident by informing the selection of disinfectant as well as the re-application time to achieve effective site remediation.

Characterization of Burkholderia pseudomallei O antigens in different clinical strains

O antigen is the major component of lipopolysaccharide LPS. The chemical structure of the O antigen determines the LPS serospecificity of the bacteria, and the diversity of O antigen is the basis for serotyping Burkholderia pseudomallei. In this study, structural elucidation of type B O antigen obtained from a clinical B. pseudomallei strain was conducted, and the effects of different types of LPS on macrophage differentiation were investigated. The O antigen was found to be composed of repeating units of [→4)-α-L-Rhap(1 → 4)-α-L-Rhap(1→2)-α-L-Rhap(1 → 2)-α-L-Rhap(1 → 3)-α-L-Rhap(1 → 3)-α-L-Rhap(1 → 4)-α-L-Rhap(1 → 6)-α-D-Galp(1→]n, where some of the →4)-α-L-Rhap(1 → units were substituted at O-3 by β-D-Xylp(1 → residues, and minor →3)-α-L-Rhap(1 → units were substituted at O-2 by β-D-Xylp(1 → residues. Meahwhile, the →6)-α-D-Galp(1 → units were substituted at O-3 by α-D-Galp(1 → residues. Furthermore, both type A and type B O antigens of B. pseudomallei could polarize macrophages toward the M1 phenotype, but the core oligosaccharides had no such activity. Therefore, we deduced that this polarization relies on the O antigen of LPS and might be related to the ability of B. pseudomallei to survive and replicate within macrophages. Thus, the characterization of different types of O antigen structural motifs is essential for further clarifying the persistence/survival mechanisms and inflammatory potential of B. pseudomallei.

Obtaining and using erythrocyte antigenic meliidosis diagnostic agent in the analysis of serum samples from meliidosis-endemic provinces Ha Giang, Lang Son and Quang Ninh of the Socialist Republic of Vietnam

Melioidosis is a particularly dangerous infection with endemic distribution caused by the Gram-negative microorganism from the pathogenicity group II Burkholderia pseudomallei. In endemic countries, melioidosis holds one of the leading places in mortality rate after HIV, tuberculosis and, in recent years, COVID-19. The natural ecological pathogen niches are located in tropical and subtropical climate zones, primarily in Southeast Asia and Australia, where its existence as a species is maintained in moist soil and water in a certain temperature environmental range. However, at present, more and more often cases of melioidosis are registered outside endemic territories, which emphasizes the relevance of improving the means and methods of laboratory diagnostics of this disease both for countries located in the zone of natural foci as well as for local healthcare of the countries after importation of this poorly known infection into their territory. In such countries, including the Russian Federation, the population has no natural immunity to the pathogen, and therefore this infection acquires even greater clinical and epidemiological significance. In the Volgograd Plague Control Research Institute, an erythrocyte antigenic melioidosis diagnostic agent for IHA was designed allowing to detect the presence of serum melioidosis antibodies. The diagnostic agent was obtained on the basis of a biological carrier ram erythrocytes sensitized with isolated protein antigenic complexes of B. pseudomallei. The high analytical characteristics of the diagnostic agent were confirmed on sera models of immunized and recovering experimental animals. Using the obtained set of reagents, the level of serum antibodies against the causative agent of melioidosis was studied in residents from the 3 provinces of Vietnam (Ha Giang, Lang Son and Quang Ninh), as well as in control group composed of residents of the Volgograd region. In samples obtained from a non-endemic region, not more than 25% of cases contained IHA titers at lower than 1:10 dilution, which is apparently due to cross-reactivity of serum immunoglobulins. Positive serum samples from clinically healthy residents of Ha Giang, Lang Son and Quang Ninh provinces were at a titer of 1:10 detected in 71.5%, in dilutions of 1:201:80 in 28.5% of cases. Thus, we believe that serum antibody titer of 1:80 established in the IHA results, has a diagnostic significance, reflecting the intensity of the anti-melioidosis populational immunity.

Synthesis and study of new siderophore analog-ciprofloxacin conjugates with antibiotic activities against Pseudomonas aeruginosa and Burkholderia spp.

Antibacterial resistance is a healthcare burden. Among Gram-negative bacteria, Pseudomonas aeruginosa belongs to the first list of antibiotic-resistant “priority pathogens” described by the World Health Organization. Formerly Pseudomonas pseudomallei, Burkholderia pseudomallei, responsible for melioidosis, is considered as a potential bioterrorist weapon by the Centers of Diseases Control and Prevention. We are interested in the development of new ways to combat these bacteria, targeted due to their high level of resistance to antibiotics via a lack of membrane permeability or efflux. Using iron transport systems is a promising strategy to bypass the bacteria cell membrane and restore the activity of conventional antibiotics such as ciprofloxacin. Specific outer membrane receptors are necessary to most microbes as they allow iron uptake, essential for their survival through siderophore-dependent mechanisms. These systems may allow the introduction of antibacterial agents, chemically coupled to a natural or synthetic siderophore molecule to form siderophore-antibiotic conjugates. In this work, we describe the synthesis of six new siderophore analog-ciprofloxacin conjugates including cleavable linker or not. The siderophore analogs correspond to a mono-catechol or a hydroxypyridinone moiety recognized by both Pseudomonas and Burkholderia species. Physico-chemical studies showed that (i) conjugates were unable to interact or cross the membrane by passive diffusion and (ii) conjugates with cleavable linker are stable in physiologic environment. Biological evaluations have highlighted a promising compound 2d, bearing an hydroxypyridinone moiety with a cleavable linker, active on a large panel of strains of Pseudomonas aeruginosa, Burkholderia pseudomallei and Burkholderia thailandensis without toxicity observed in vitro.

Melioidosis: A Case Report of Confirmed Burkholderia Pseudomallei in Rangpur Medical College Hospital, Rangpur

Bangladesh is an example of a highly populous, agricultural country where melioidosis may be a significantly underdiagnosed cause of infection and death. Melioidosis is caused by a highly pathogenic, soil-borne, Gram-negative bacterium, Burkholderia pseudomallei. Diabetes mellitus is the most common risk factor. Disease manifestations vary from pneumonia or localized abscess to acute septicemia or arthritis. Culture is considered the current gold- standard for diagnosis. For the intensive phase (10 to 14 days), ceftazidime or meropenem is the drug of choice. For the eradication phase (3 to 6 months), oral trimethoprim/ sulfamethoxazole is the drug of choice. Surgery (drainage of abscess) has an important role in the management of melioidosis. A 48-year-old male, health worker of an NGO, working at Cox’s Bazar presented with fever for 1 month and gradual increasing pain and swelling of the left knee for 7 days followed by cellulitis and multiple abscess formation in the left leg. B. pseudomallei isolated from blood culture and successfully treated with meropenem.&#x0D; J Rang Med Col. September 2022; Vol. 7, No. 2:69-72

Pathogenicity and virulence of Burkholderia pseudomallei

ABSTRACT The soil saprophyte, Burkholderia pseudomallei, is the causative agent of melioidosis, a disease endemic in South East Asia and northern Australia. Exposure to B. pseudomallei by either inhalation or inoculation can lead to severe disease. B. pseudomallei rapidly shifts from an environmental organism to an aggressive intracellular pathogen capable of rapidly spreading around the body. The expression of multiple virulence factors at every stage of intracellular infection allows for rapid progression of infection. Following invasion or phagocytosis, B. pseudomallei resists host-cell killing mechanisms in the phagosome, followed by escape using the type III secretion system. Several secreted virulence factors manipulate the host cell, while bacterial cells undergo a shift in energy metabolism allowing for overwhelming intracellular replication. Polymerisation of host cell actin into “actin tails” propels B. pseudomallei to the membranes of host cells where the type VI secretion system fuses host cells into multinucleated giant cells (MNGCs) to facilitate cell-to-cell dissemination. This review describes the various mechanisms used by B. pseudomallei to survive within cells.

Comparative Analysis of Potential Determinants of Resistance to Aminoglycosides in &lt;i&gt;Burkholderia pseudomallei&lt;/i&gt; Strains with Different Level of Sensitivity to Gentamicin

The aim of the study was to identify and compare potential determinants of aminoglycoside resistance in gentamicin susceptible Burkholderia pseudomallei strains.Materials and methods. A bioinformatics analysis of whole genome shotgun sequences of three B. pseudomallei strains having different levels of sensitivity to gentamicin was carried out.Results and discussion. B. pseudomallei is intrinsically resistant to aminoglycosides. Such strains, as a rule, are not taken into account in the classical scheme of isolation and identification. At the same time, there were no significant differences in the clinical manifestations of melioidosis during infection with gentamicin-resistant and sensitive strains. In B. pseudomallei strains of different sequence types (ST70, ST948, and ST1566), point missense mutations were found in the genes of three efflux pumps of the RND family: AmrAB-OprA, BpeAB-OprB, BpeEF-OprC, and one with unknown functions, as well as in the gene aminoglycoside-6’-N-acetyltransferase AAC(6’)-III. All three strains had amino acid substitutions in the AmrA periplasmic linker: ARG160SER, Arg116Gln and Gly237Arg, Thr317Lys, respectively. In moderately sensitive strains (ST948 and ST1566), an identical Val222Met substitution was found in the repressor of the AmrAB-OprA operon, AmrR. It is likely that the intermediate level of sensitivity to gentamicin in the studied strains is mediated by the constitutive expression of the AmrAB-OprA operon, which partially compensates for the structural defects. It is also possible that a dinucleotide deletion in the AAC (6’)-III aminoglycoside-6’-N-acetyltransferase gene, as well as detected mutations in the homologues of the periplasmic linker (BPSL2234) of an uncharacterized efflux operon of the RND family, are involved in the loss of resistance to gentamicin.

Biofilm Signaling, Composition and Regulation in Burkholderia pseudomallei.

The incidence of melioidosis cases caused by the gram-negative pathogen Burkholderia pseudomallei (BP) is seeing an increasing trend that has spread beyond its previously known endemic regions. Biofilms produced by BP have been associated with antimicrobial therapy limitation and relapse melioidosis, thus making it urgently necessary to understand the mechanisms of biofilm formation and their role in BP biology. Microbial cells aggregate and enclose within a self-produced matrix of extracellular polymeric substances (EPSs) to form biofilm. The transition mechanism of bacterial cells from planktonic state to initiate biofilm formation, which involves the formation of surface attachment microcolonies and the maturation of the biofilm matrix, is a dynamic and complex process. Despite the emerging findings on the biofilm formation process, systemic knowledge on the molecular mechanisms of biofilm formation in BP remains fractured. This review provides insights into the signaling systems, matrix composition, and the biosynthesis regulation of EPSs (exopolysaccharide, eDNA and proteins) that facilitate the formation of biofilms in order to present an overview of our current knowledge and the questions that remain regarding BP biofilms.

Functional Activities of O-Polysaccharide and Hemolysin Coregulated Protein 1 Specific Antibodies Isolated from Melioidosis Patients.

Melioidosis is a fatal tropical disease caused by the environmental Gram-negative bacterium, Burkholderia pseudomallei. This bacterium is intrinsically resistant to several antibiotics and treatment of melioidosis requires prolonged antibiotic administration. To date, there are no vaccines available for melioidosis. Previous studies have shown that humoral immunity is critical for surviving melioidosis and that O-polysaccharide (OPS) and hemolysin coregulated protein 1 (Hcp1) are important protective antigens in animal models of melioidosis. Our previous studies revealed that melioidosis patients had high levels of OPS- and Hcp1-specific antibodies and that IgG against OPS (IgG-OPS) and Hcp1 (IgG-Hcp1) were associated with patient survival. In this study, we characterized the potential function(s) of IgG-OPS and IgG-Hcp1 from melioidosis patients. IgG-OPS and IgG-Hcp1 were purified from pooled serum obtained from melioidosis patients using immuno-affinity chromatography. Antibody-dependent cellular phagocytosis assays were performed with pooled serum from melioidosis patients and compared with serum obtained from healthy controls. Serum from melioidosis patients significantly enhanced B. pseudomallei uptake into the human monocytic cell line THP-1 compared with pooled serum from healthy donors. Enhanced opsonization was observed with IgG-OPS and IgG-Hcp1 in a dose-dependent manner. Antibody-dependent complement deposition assays were performed with IgG-OPS and IgG-Hcp1 using flow cytometry and showed that there was enhanced C3b deposition on the surface of B. pseudomallei treated with IgG-OPS but to a lesser degree with IgG-Hcp1. This study provides insight into the function of IgG-OPS and IgG-Hcp1 in human melioidosis and supports that OPS and Hcp1 are potential vaccine antigens for immunization against melioidosis.

Challenges in Managing Melioidosis with Fulminant Sepsis: A Case Report

Managing melioidosis with fulminant sepsis is difficult and challenging. We describe the case of a 30-year-old man with clinical presentation of non-specific septicemic shock with multi organ impairment and severe respiratory distress. The causative organism, Burkholderia pseudomallei was only identified on day 4 of ICU admission. Imaging investigation revealed multiple lung and splenic abscesses. This led to delay in the diagnosis and initiating specific antimicrobial therapy which arise from difficulties in clinical recognition and laboratory diagnosis. Our patient was managed in the ICU for 23 days with intensive antimicrobial therapy. As for now, we should increase the awareness of melioidosis in treating our patients and realize its burden to our community and hoping that a better diagnostic test will arise and helps us in achieving early confirmatory diagnosis and guide for better therapeutic efficacy and survival of the patients.

A clinical study on clinical features,manifestations and drug resistance of melioidosis.

To explore the clinical features, manifestations and drug resistance of melioidosis. The clinical data of 45 melioidosis patients treated by Affiliated Haikou Hospital of Xiangya Medical College, Central South University during January 2015 and January 2020 were studied. Informaiton collected included age, birthplace, area of residence, sex, ethnic group, clinical symptoms or signs, colony culture results, degree of drug resistance, treatment regimens and outcomes, department of initial diagnosis, and specimen type, thereby giving an analysis of the clinical features, manifestations, and treatment outcomes of the disease. Body fluids were obtained from all patients to analyze the drug resistance of the bacterium Burkholderia pseudomallei based on colony culture and susceptibility test results. In the 45 cases of melioidosis, the clinical manifestations predominantly included low fever (31.11%), pulmonary infection (22.22%); auxiliary examinations often suggested increases in C reactive protein (CRP) (73.33%), white blood cell count (#WBC) (68.89%) and procalcitonin (PCT) (66.67%); susceptibility test results showed that Burkholderia pseudomallei yielded high sensitive rate to antibacterials including trimethoprim-sulfamethoxazole (SXT) (88.89%),ceftazidime (CAZ)(93.33%), meropenem (MEM) (100.00%), imipenem (IPM)(100.00%); Of the 45 melioidosis patients, 23 were cured (51.11%), and 21 showed an improvement (33.33%) or remained stable (13.33%); A relatively high percentage of the patients experienced post-discharge recurrence/aggravation (recurrence within six months: 4.44%; recurrence within a year: 6.67%). Low fever, pulmonary infection, and increases in serum inflammatory markers are major clinical features of melioidosis. Burkholderia pseudomallei presents high resistance rates to antibacterials such as GEN, FEP, AMP, and IPM.

MELIOIDOSIS: THE "GREAT MIMICKER"

SESSION TITLE: Pulmonary Manifestations of Infections SESSION TYPE: Case Reports PRESENTED ON: 10/17/2022 03:15 pm - 04:15 pm INTRODUCTION: Melioidosis, caused by Burkholderia pseudomallei, is often referred to as a "great mimicker” as it is often mis-diagnosed and under-reported due to its widely variable clinical presentation (1). Here we discuss a patient who presented with a constellation of symptoms that were mistaken for other disease processes prior to a melioidosis diagnosis. CASE PRESENTATION: A 71 year old male of Haitian descent with recent travel to Haiti presented with >1 month of persistent fevers and worsening diffuse weakness and arthralgias. The patient was first empirically treated for Q fever with doxycycline and hydroxychloroquine at a different hospital prior to presentation. Upon presentation to this facility, he underwent further work-up for a variety of infectious etiologies including chikungunya, malaria, and lyme disease due to his presentation with a multi-system process and recent travel. The patient's blood and joint aspirate cultures returned positive for Burkholderia pseudomallei and he was subsequently diagnosed with melioidosis. He was discharged on long-term antibiotic treatment with meropenem. The patient then re-presented to the ED approximately a week after discharge with signs of worsening disease including bilateral multifocal pneumonia. Imaging showed multiple pneumothoraces complicated by lung collapse and respiratory failure. The patient also had worsening neurological manifestations and further bone and joint involvement. CDC analysis of cultures identified resistance to meropenem. The patient was switched to ceftazidime and trimethoprim-sulfamethoxazole before escalation to imipenem. The patient expired six weeks from initial presentation due to worsening pulmonary and neurologic manifestations. DISCUSSION: As of 2020, only one confirmed case of melioidosis has been documented in the U.S. since 1945 (2). The incidence of this infection is reportedly increasing throughout the world and regions of endicimity are expanding. Its difficulty to diagnose contributes to a high mortality rate of 20-50% as of 2020 (2). 50% of patients will present with bacteremia and 20% of patients will progress to a fulminant septicemia (1). CONCLUSIONS: This case report identifies a case of melioidosis with both classic disease manifestations (pulmonary involvement), as well as less common manifestations (bone and joint involvement) and emphasizes the need for a broad differential when the patient presents with a non-specific, multi-organ clinical syndrome after travel. Although previously thought to be endemic only to Asian and Australian populations, more and more cases are being seen in South America, central America, and the Caribbean (2). With this being the case, the incidence of Melioidosis has the potential to increase in the U.S and further discussion of epidemiology, clinical presentation, and treatment is warranted for critical care, pulmonology, infectious disease, and primary care physicians. Reference #1: Chakravorty A, Heath CH. Melioidosis: An updated review. Australian Journal of General Practice. 2019;48(4):327-332. doi:10.31128/ajgp-04-18-4558 Reference #2: Gassiep I, Armstrong M, Norton R. Human melioidosis. Clinical Microbiology Reviews. 2020;33(2). doi:10.1128/cmr.00006-19 DISCLOSURES: No relevant relationships by Rose Puthumana No relevant relationships by Rachel Werne

Clinical Utility of Combined Whole-cell Antigen and Recombinant Hemolysis Co-regulated Protein 1-Enzyme-linked Immunosorbent Assays Reveals Underdiagnosed Cases of Melioidosis in Vietnam.

Melioidosis is a fatal infectious disease in the tropics and subtropics. Currently, bacterial culture is the gold standard for diagnosis of the disease, but its sensitivity is relatively low. In this study, we evaluated four ELISAs using sera collected from culture-confirmed cases of melioidosis (n = 63), cases with other bacterial infections (n = 62), and healthy donors (n = 60). Antigens used for ELISAs were the whole-cell (WC) antigens and recombinant proteins of hemolysis co-regulated protein 1 (Hcp1), GroEL1, and alkyl hydroperoxide reductase subunit C (AhpC). Using the cutoff values for optical density at 490 nm defined at a specificity of > 95%, the sensitivity of the WC, Hcp1, GroEL1, and AhpC ELISAs was 93.7%, 87.3%, 61.9%, and 57.1%, respectively. The combined WC/Hcp1 ELISA showed the greatest sensitivity and specificity of 98.4% and 95.1%, respectively. Of 511 and 500 sera collected from clinically suspected febrile patients admitted to the General Hospital of Ha Tinh Province and the Hue Central Hospital, respectively, combined WC/Hcp1 ELISAs showed 52 (10.2%) and 41 (8.2%) patients positive for melioidosis, respectively. The assay detected 14 of 14 (100%) and 21 of 23 (91.3%) culture-confirmed cases of melioidosis at Ha Tinh and Hue, respectively. A follow-up study of 38 patients positive for melioidosis by combined WC/Hcp1 ELISAs but negative for Burkholderia pseudomallei by culture method or not assigned to examine for bacterial culture resulted in 2 (5.3%) culture-reconfirmed patients with melioidosis, 9 (23.7%) deaths, 17 (44.7%) unhealthy patients, and 10 (26.3%) healthy persons. Combined WC/Hcp1 ELISA was a reliable serological method to detect underdiagnosed cases of melioidosis. Further investigations are needed to estimate the true sensitivity and specificity of the assay and the true number of cases of melioidosis.