Melioidosis masquerading as malignancy in tropical Australia; lessons for clinicians and implications for clinical management

Melioidosis is a life-threatening, emerging infectious disease caused by the environmental bacterium Burkholderia pseudomallei. Melioidosis is hyperendemic in tropical Australia and southeast Asia, however the disease is increasingly encountered beyond these regions. Early diagnosis is essential as the infection has a case-fatality rate of up to 50 %. Melioidosis most commonly involves the lungs, although almost any organ can be affected. Most patients present acutely but an insidious presentation over weeks to months is also well described. We present a case series of 7 patients from tropical Australia whom local clinicians initially believed to have cancer ‒ most commonly lung cancer ‒ only for further investigation to establish a diagnosis of melioidosis. All 7 patients had comorbidities that predisposed them to developing melioidosis and all survived, but their delayed diagnosis resulted in 3 receiving anti-cancer therapies that resulted in significant morbidity. The study emphasises the importance of thorough diagnostic evaluation and repeated collection of microbiological samples. It is hoped that our experience will encourage other clinicians ‒ in the appropriate clinical context ‒ to consider melioidosis as a potential explanation for a patient's presentation, expediting its diagnosis and the initiation of potentially life-saving therapy.

Development of a novel sequence based real-time PCR assay for specific and sensitive detection of Burkholderia pseudomallei in clinical and environmental matrices

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.

Synthesis of BLF1-containing trimethyl chitosan nanoparticles and evaluation of its immunogenicity and protection in syrian mice by oral and subcutaneous injections

The bacterium Burkholderia pseudomallei is the cause of melioidosis infectious disease. In this bacterium, the BLF1 protein wide inhibits the synthesis of proteins in human cells. This disease is reported to cause a death rate of 40% in some parts of the world. Currently, no effective vaccine is available against this bacterial infection. In this study, therefore, a Nano vaccine was synthesized based on the trimethyl chitosan (TMC) polymer containing the BLF1 recombinant protein, and its immunogenicity and protection in Syrian mice were evaluated by oral and subcutaneous injections. The BLF1 recombinant protein expression was induced in Escherichia coli Bl21 (DE3) and purified by the affinity chromatography technique. Recombinant protein-containing nanoparticles (NPs) were then synthesized by the ionotropic gelation method. After oral and subcutaneous injections, antibody titration was assessed by the indirect ELISA assay. Finally, murine groups were challenged using the BLF1 toxin. The results indicated that the immune system showed more antibody titration in subcutaneous injection than in the oral form. However, the results were reversed in the challenge results, and the survival rate was more significant in the oral injection.

Multi-systemic melioidosis in a patient with type 2 diabetes in non-endemic areas: A case report and review of literature

BACKGROUND

Melioidosis, an infectious disease caused by Burkholderia pseudomallei (B. pseudomallei), occurs endemically in Southeast Asia and Northern Australia and is a serious opportunistic infection associated with a high mortality rate.

CASE SUMMARY

A 58-year-old woman presented with scattered erythema on the skin of her limbs, followed by fever and seizures. B. pseudomallei was isolated successively from the patient's urine, blood, and pus. Magnetic resonance imaging showed abscess formation involving the right forehead and the right frontal region. Subsequently, abscess resection and drainage were performed. The patient showed no signs of relapse after 4 months of follow-up visits post-treatment.

CONCLUSION

We present here a unique case of multi-systemic melioidosis that occurs in non-endemic regions in a patient who had no recent travel history. Hence, it is critical to enhance awareness of melioidosis in non-endemic regions.

Assessing the national antibiotic surveillance data to identify burden for melioidosis in Malaysia

Objectives

A leading cause of morbidity and mortality in Southeast Asia, the epidemiological data on melioidosis disease occurrence and mortality in Malaysia is not comprehensive. The aim of this study is to determine the burden of melioidosis and assess the National Surveillance for Antibiotic Resistance (NSAR) data as a potential tool melioidosis surveilance in Malaysia.

Methods

We performed a retrospective analysis on the B. pseudomallei reposited data submitted to the NSAR network between January 2014 and December 2020. The data were screened for information on patient demographics and specimen types. Additional patient comorbidities and outcomes were drawn from parallel surveillance for bacteremic melioidosis.

Results

The average annual incidence rate of melioidosis between 2014-2020 was 3.41 per 100,000 population and was significantly different between states (P <0.001). The highest incidence was observed in Pahang at 11.33 per 100,000 population. Individuals of Malay ethnicity, from the states of Pahang, Johor, Perak, and Negeri Sembilan aged 40-49, who were diabetic and working in agriculture-related sectors had a higher risk of succumbing to the infection.

Conclusion

Assessing the NSAR data proved to be a useful tool for the determination of the incidence and socio-demographic risk factors attributed to melioidosis in Malaysia.

BpOmpW antigen administered with CAF01 adjuvant stimulates comparable T cell responses to Sigma adjuvant system

There are no licensed vaccines to protect vulnerable populations from the potentially fatal tropical infection, melioidosis, despite its causative agent, Burkholderia pseudomallei, being endemic in tropical and subtropical regions. A promising vaccine candidate, BpOmpW protected mice from melioidosis infection for up to 81 days and stimulated robust interferon gamma responses in CD4+, CD8+, NK and NKT cells. In order to progress to human studies, selection of an adjuvant with an acceptable human safety profile that stimulates appropriate correlates of protection is essential. Here we demonstrate that the CAF01 vaccine adjuvant elicits optimal immune correlates of protection when administered with our BpOmpW vaccine. Specifically, we demonstrate that CAF01 administered with BpOmpW elicits robust Th1 responses, with potent IFN-γ responses in CD4+ and CD8+ T cells and NKT cells, in addition to Th17 and Th2 responses. This formulation will be particularly effective in protecting susceptible populations including people with type 2 diabetes from melioidosis.

Optimal control and cost-effectiveness analysis for the human melioidosis model

In this work, we formulated and investigated an optimal control problem of the melioidosis epidemic to explain the effectiveness of time-dependent control functions in controlling the spread of the epidemic. The basic reproduction number ( R 0 c ) with control measures is obtained, using the next-generation matrix approach and the impact of the controls on R 0 c is illustrated numerically. The optimal control problem is analyzed using Pontryagin's maximum principle to derive the optimality system. The optimality system is simulated using the forward-backward sweep method based on the fourth-order Runge-Kutta method in the MATLAB program to illustrate the impact of all the possible combinations of the control interventions on the transmission dynamics of the disease. The numerical results indicate that among strategies considered, strategy C is shown to be the most effective in reducing the number of infectious classes compared to both strategy A and strategy B. Furthermore, we carried out a cost-effectiveness analysis to determine the most cost-effective strategy and the result indicated that the strategy B (treatment control strategy) should be recommended to mitigate the spread and impact of the disease regarding the costs of the strategies.

Are we dealing with melioidosis under the mask of tuberculosis? - A case series

Melioidosis is prevalent in South-East Asia. India is now become endemic to melioidosis. Melioidosis mimicks Tuberculosis (TB) and is often overlooked clinically. The spectrum of disease ranges from acute pulmonary infection to focal infection and septicemia. We report three cases of melioidosis, which was primarily suspected to be tuberculosis due to similarities in the clinical features. All patients were male and had risk factors such as type 2 diabetes mellitus as well as other risk factors such as chronic obstructive pulmonary disease (COPD), systemic hypertension, glucocorticoid therapy etc. All three patient samples were culture negative as well as negative for tests performed for the detection of tuberculosis. Conventional nested PCR targeting 251bp of 16S-23S spacer region of B. pseudomallei. was performed among individuals suspected to have extrapulmonary Tuberculosis. The presence of 251 bp was considered positive for B. pseudomallei. All three patients were treated with third generation cephalosporin and recovered due to timely diagnosis. Patients suspected for tuberculosis should be screened for B. pseudomallei, especially when AFB smear and MTB GeneXpert are negative. Often clinical samples may be culture negative for B. pseudomallei as patients are treated with antibiotics, therefore it is worthwhile performing PCR for B. pseudomallei to rule in a diagnosis of melioidosis and initiate appropriate antibiotics.

MALDI-TOF MS analysis of Burkholderia pseudomallei and closely related species isolated from soils and water in Khon Kaen, Thailand

Melioidosis is caused by Burkholderia pseudomallei (Bp) acquired from the environment. Conventional identification methods for environmental Bp are challenging due to the presence of closely related species. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is accurate for bacterial identification, but has been little used to identify Bp from environmental samples. This study aims to evaluate MALDI-TOF MS for the identification of Bp and closely related species isolated from environmental samples in Thailand using whole-genome sequencing (WGS) as the gold standard, including determining the best sample preparation method for this purpose. We identified Bp (n = 22), Burkholderia spp. (n = 28), and other bacterial species (n = 32) using WGS. MALDI-TOF analysis of all Bp isolates yielded results consistent with WGS. A decision-tree algorithm identified 16 important variable peaks, using the protein extraction method (PEM), demonstrating distinct MALDI-TOF profiles for the three categories (Bp, Burkholderia spp. and "other bacterial species"). Three biomarker peaks (4060, 5196, and 6553 Da) could discriminate Bp from other Burkholderia and closely related species with 100% sensitivity and specificity. Hence, the MALDI-TOF technique has shown its potential as a species discriminatory tool, providing results comparable to WGS for classification and surveillance of environmental Bp.

Paediatric melioidosis

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.

Role of type VI secretion system protein TssJ-3 in virulence and intracellular survival of Burkholderia pseudomallei

TssJ-3 is an outer-membrane lipoprotein and is one of the key components of the type VI secretion system in Burkholderia pseudomallei. TssJ translocates effector proteins to target cells to induce innate immune response in the host. However, the tssJ gene has not been identified in B. pseudomallei and its function in this bacterium has not yet been characterized. tssJ-3 knockout and tssJ-3-complemented B. pseudomallei strains were constructed to determine the effects of tssJ-3 on bacterial growth, biofilm formation, flagellum synthesis, motility, host cell infection, and gene expression in B. pseudomallei. We found that the ΔtssJ-3 mutant strain of B. pseudomallei showed significantly suppressed biofilm formation, flagellum synthesis, bacterial growth, motility, and bacterial invasion into host cells (A549 cells). Furthermore, the ΔtssJ-3 mutation downregulated multiple key genes, including biofilm and flagellum-related genes in B. pseudomallei and induced interleukin-8 gene expression in host cells. These results suggest that tssJ-3, an important gene controlling TssJ-3 protein expression, has regulatory effects on biofilm formation and flagellum synthesis in B. pseudomallei. In addition, B. pseudomallei-derived tssJ-3 contributes to cell infiltration and intracellular replication. This study provides a molecular basis of tssJ-3 for developing therapeutic strategies against B. pseudomallei infections.

Melioidosis Vaccines (MeVa): Attitudes to vaccines, melioidosis and clinical trials in key stakeholders in Ubon Ratchathani, Thailand

Background: Melioidosis is a bacterial infection which kills an estimated 89,000 people per year in tropical and sub-tropical regions, chiefly affecting the poorest. Diabetes is the primary risk factor, conferring a 12-fold increase in risk. Despite limited funding compared to other neglected tropical diseases, melioidosis vaccine development has generated several candidates for clinical development. CPS-CRM 197/Hcp1 is a promising vaccine candidate developed at the University of Nevada, Reno which is due to enter a Phase I clinical trial in Oxford, UK in 2024. As we move closer to the possibility of field trials of a melioidosis vaccine, it is critical to work in parallel to understand perceptions toward a vaccine among those living where melioidosis rates are high. Reasons for vaccine acceptance versus hesitancy are complex, and include perceived risk of the target disease, concern about side effects, and above all trust in government, scientists, the pharmaceutical industry and other authorities. Methods: We will carry out a qualitative study in Ubon Ratchathani, Thailand, an endemic region for melioidosis, as groundwork for a potential future melioidosis vaccine efficacy study, and in the longer-term vaccine introduction. This study seeks to explore knowledge and attitudes in three main areas; 1) melioidosis disease, 2) vaccines, and 3) participation in clinical vaccine trials. In-depth interviews and focus group discussions will take place in five participant groups of different risks and exposure to melioidosis. Purposive, convenience sampling will be used, also snowball sampling to reach some participant groups. Sample size will be based on participant's experience, to inform the line of enquiries of study, or until data saturation, expecting 66-90 participants across all groups. Discussion: The findings of this study will be written up and published in an open access journal, and will be valuable to inform future design of clinical trials as well as engagement and communications associated with future vaccine rollout.

Development of neutropenic sepsis during the eradication phase with co-trimoxazole in patients with melioidosis: two case reports

Introduction

Burkholderia pseudomallei is the bacterium that causes melioidosis. It is mostly a tropical disease, and particularly common in Southeast Asia and northern Australia. The intensive intravenous phase and the oral prolonged eradication phase are the two phases of melioidosis treatment. The current recommended treatment for melioidosis eradication is oral co-trimoxazole (TMP/SMX).

Case report

Two patients were diagnosed with B. pseudomallei bacteremia without a focus and were treated with oral TMP/SMX with folic acid during the eradication phase. Both presented with neutropenic sepsis with pneumonia and pyelonephritis at days 48 and 45 following TMP/SMX 320/1600 mg q12h (4 tablets) and in both of them, the folic acid compliance was poor. One patient died and the other survived following intensive treatment for neutropenia. At the presentation following neutropenic sepsis among both patients, the red blood cells and platelets were within normal limits. Both patients were on a high dose of TMP/SMX, as both were within 40-60 kg of body weight the ideal TMP/SMX dose would be 240/1200 mg q12h (3 tablets). Pancytopenia caused by TMP/SMX can frequently develop gradually over time. Alternately, it can develop rapidly and swiftly escalate to fulminant sepsis, disseminated intravascular coagulation, and fast hemolysis. However, the development of isolated neutropenia is rarely described in the literature.

Conclusions

Prolonged use of TMP/SMX is important to eradicate B. pseudomallei and always the possibility of rare adverse effects has to be considered. Always weight-based TMP-SMX dosing has to be encouraged with need to ensure the compliance of folic acid. During the eradication phase, continuous monitoring of blood cell lines with weekly full blood count would be essential to identify neutropenia in advance.

Emergence of melioidosis in Brazil: a case series

BACKGROUND

Melioidosis is a serious disease caused by the bacterium Burkholderia pseudomallei which affects humans and animals. It results in a wide spectrum of clinical manifestations, mainly in the respiratory tract, progressing to septic shock and death.

CASE PRESENTATION

Herein, we present a series of seven patients (median age: 41 years) with confirmed melioidosis, treated at a public hospital in Piauí State, Brazil between 2019 and 2021. The most common clinical presentations were fever, cough, pneumonia, and abdominal pain. The mean duration of antibacterial therapy with 1 g of meropenem was 28.6 ± 1.1 days. Six patients recovered and one died. The mean hospitalization time was 51.0 ± 39.2 days.

CONCLUSIONS

Melioidosis is an emerging infectious disease in Brazil. Health professionals in endemic areas need to be aware of the clinical presentation and appropriate clinical management of the disease because early diagnosis and early initiation of antibiotic therapy can be life-saving.

Efficacy and safety of co-trimoxazole in eradication phase of melioidosis; systematic review

BACKGROUND

Melioidosis is an infectious disease caused by the bacterium Burkholderia pseudomallei. The two stages of melioidosis treatment are the intense intravenous phase and the oral eradication phase. Although co-trimoxazole has been in use for several years, the literature does not demonstrate uniformity of the drug doses, combinations, or durations suitable for the eradication phase of melioidosis. The safety profile of co-trimoxazole was not documented in the literature, nor have systematic studies of its effectiveness been done. This systematic review sought to study on the dose, duration and combination of co-trimoxazole therapy in view of clinical efficacy and safety in the eradication phase of melioidosis.

MAIN BODY

This systematic review included all of the published articles that employed co-trimoxazole in the eradication phase after 1989, including, randomized clinical trials, case-control studies, cohorts, case reports, and case series. Throughout the eradication (maintenance) phase, co-trimoxazole usage was permissible in any dose for any period. A total of 40 results were included in the analysis which contained six clinical trials, one cohort study, one Cochrane review, and thirty-two case series/case reports. Clinical and microbial relapse rates are low when co-trimoxazole is used in single therapy than in combination. There were several adverse events of co-trimoxazole, however, a quantitative analysis was not conducted as the data did not include quantitative values in most studies.

SHORT CONCLUSION

The dose of co-trimoxazole, duration of the eradication phase, and other combinations used in the treatment was varying between studies. Compared to combined therapy patients treated with co-trimoxazole alone the mortality and relapse rates were low. The lowest relapse rate and lowest mortality rate occur when using co-trimoxazole 1920 mg twice daily. The duration of therapy varies on the focus of melioidosis and it is ranged from 2 months to one year and minimum treatment duration associated with low relapse rate is 3 months. The use of co-trimoxazole over the maintenance phase of melioidosis is associated with clinical cure but has adverse effects.

Focal pachymeningitis in a returning traveler: Don't forget melioidosis

Background

Melioidosis is an endemic disease in South-East Asia and Northern Australia caused by a Gram-negative bacillus, Burkholderia pseudomallei. Manifestations are wide and neurological involvement have rarely been described.

Methods

In this paper, we report a patient returning from Asia with an unusual infection including CNS involvement consistent with a melioidosis.

Results

This diagnosis was challenging and complex to carry out with multiple considerations, mainly because of the atypical nature of the germ. Burkholderia pseudomallei can be easily misidentified with Burkholderia thailandensis (rarely pathogenic to humans) during bacterial culture because of their phylogenetic proximity. The main pitfall of the management was that the responsible infectious agent was not referenced in the MALDI-TOF (considered as a bioterrorism agent) and led to a wrong strategy.

Conclusions

This case of melioidosis shows the difficulty regarding the diagnosis of this disease in a patient returning from an endemic zone and its frequent multiple organs involvement. Melioidosis is an emerging, potentially fatal disease which requires prolonged antibiotic treatment. Difficulties in clinical microbiology laboratories diagnosis of melioidosis, especially in non-endemic areas where clinical suspicion is low, may delay treatment and affect disease outcomes.

Nasopharyngeal melioidosis: a case report

A 12-year-old boy was admitted after 11 days of fever and 2 days of nasal obstruction as well as swelling of a right cervical lymph node. Nasal endoscopy and computed tomography of the neck showed a nasopharyngeal mass occupying the entire nasopharynx, extending into the nasal cavity, and obliterating the fossa of Rosenmuller. Abdominal ultrasonography revealed a small solitary splenic abscess. Although a nasopharyngeal tumor or malignancy was initially considered, biopsy of the mass showed only suppurative granulomatous inflammation, and bacterial culture from the enlarged cervical lymph node yielded Burkholderia pseudomallei. The symptoms, nasopharyngeal mass, and cervical lymph node enlargement resolved with melioidosis-directed antibiotic therapy. Although rarely reported, the nasopharynx may be an important primary site of infection in melioidosis patients, especially in pediatric patients.

Letter in Response to "Melioidosis in a Tertiary Care Center from South India: A 5-year Experience

How to cite this article: Behera B, Mohanty S, Mishra B, Mohapatra PR. Letter in Response to "Melioidosis in a Tertiary Care Center from South India: A 5-year Experience. Indian J Crit Care Med 2023;27(5):368-369.

Risk Factors for Melioidosis Mortality and Epidemics: A Multicentre, 10-Year Retrospective Cohort Study in Northern Hainan

INTRODUCTION

Burkholderia pseudomallei is a gram-negative environmental bacterium and aetiological agent of melioidosis, a tropical infectious disease with diverse clinical presentations. We aimed to describe the epidemiological and clinical characteristics of melioidosis in northern Hainan and to determine the meteorological factors affecting its morbidity.

METHODS

We conducted a retrospective, multicentre, observational cohort study of 90 patients with melioidosis admitted to four general hospitals in northern Hainan from 2010 to 2020. Epidemiological, clinical presentation, laboratory and treatment outcome data were collected and analysed. The monthly incidence of melioidosis and meteorological data, including precipitation, temperature, humidity, air pressure and wind speed, for the same period were collected to analyse the relationship between meteorological factors and the incidence of melioidosis.

RESULTS

Of the 90 patients included in the study, 79 (87.78%) were male. Patient age ranged from 10 to 81 years old, but most patients, namely, 78 (86.67%), were middle-aged and elderly people aged 41-81 years old. Forty-six patients (51.11%) were farmers. The number of cases increased significantly after 2014, with the highest numbers occurring in 2014 and 2016. The highest number of cases occurred in summer and autumn and were associated with abundant rainfall, and 58 cases (64.44%) occurred from July to December. The patients showed diverse presentations and abnormal laboratory parameters: 69 patients (76.67%) had a history of diabetes mellitus; bacteremia was present in 50 patients (55.56%), sepsis was present in 39 patients (43.33%) and pneumonia in 19 patients (21.11%). An average high-sensitivity C-reactive protein (hs-CRP) level of 149.57 ± 13.65 mg/L and a median procalcitonin (PCT) level of 1.31 (0.39, 6.21) ng/mL were observed. Among all the cases, 21 (23.33%) were identified as acute infections, 51 (56.67%) as subacute infections and 18 (20.00%) as chronic infections. Six patients (6.67%) died of illness; five of these patients were male, and five of these patients were middle-aged and elderly patients. The monthly average precipitation was significantly positively correlated with the monthly average incidence of melioidosis (r = 0.74, P < 0.01).

CONCLUSION

Male patients, farmers and especially middle-aged and elderly individuals with a history of diabetes mellitus accounted for most of the patients. The majority of cases were concentrated in coastal areas. Most cases of melioidosis occurred during the rainy seasons, and the monthly average precipitation was an independent factor affecting the average monthly incidence of melioidosis.

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.

A case series of melioidosis: An underdiagnosed infection

Melioidosis is an infection caused by Burkholderia pseudomallei. It is a non notifiable disease and is not included in Integrated Disease Surveillance Program by National Center of Disease Control. India is predicted to have highest burden of disease with an estimated mortality of 32,000 per year. Melioidosis presents with a wide range of clinical manifestations like pneumonia, liver and splenic abscess, septicemia etc. This wide spectrum of presentation and mimicry with other infections leads to its misdiagnosis or underdiagnosis. The only source of disease burden in India is few case reports and the true burden and distribution of disease still needs to be assessed. We, hereby, report a case series of four cases aged 28 years, 53 years, 33 years and 22 years. All cases had different clinical presentation ranging from abdominal wall abscess to septicemia and neurological manifestations making the diagnosis challenging. Three of the four cases were discharged after complete recovery while one case went leave against medical advice. To our knowledge this is the first series describing complete recovery of three out of four cases. This case series will help the physicians to raise their index of clinical suspicion of melioidosis in high risk patients presenting with various findings thus improving the chances of correct diagnosis and treatment.

The effect of climate on melioidosis incidence in Townsville, Australia: a dry tropical region

BACKGROUND

Townsville is in the dry tropics in Northern Australia and an endemic region for melioidosis. Melioidosis is an infectious disease caused by Burkholderia pseudomallei, a soil dwelling organism. The incidence of melioidosis is associated with high levels of rainfall and has been linked to multiple weather variables in other melioidosis endemic regions such as in Darwin. In contrast to Townsville, Darwin is in the wet-dry tropics in Northern Australia and receives 40% more rainfall. We assessed the relationship between melioidosis incidence and weather conditions in Townsville and compared the patterns to the findings in Darwin and other melioidosis endemic regions.

METHOD

Performing a time series analysis from 1996 to 2020, we applied a negative binomial regression model to evaluate the link between the incidence of melioidosis in Townsville and various weather variables. Akaike's information criterion was used to assess the most parsimonious model with best predictive performance. Fourier terms and lagged deviance residuals were included to control long term seasonal trends and temporal autocorrelation.

RESULTS

Humidity is the strongest predictor for melioidosis incidence in Townsville. Furthermore, the incidence of melioidosis showed a three-times rise in the Townsville region when >200 mm of rain fell within the fortnight. Prolonged rainfall had more impact than a heavy downpour on the overall melioidosis incident rate. There was no statistically significant increase in incidence with cloud cover in the multivariable model.

CONCLUSION

Consistent with other reports, melioidosis incidence can be attributed to humidity and rainfall in Townsville. In contrast to Darwin, there was no strong link between melioidosis cases and cloud cover and nor single large rainfall events.

Concomitant extradural, subdural, and intraparenchymal abscesses of the brain in a patient with cerebral melioidosis - A case report

Background

Extra axial abscess of the brain is a rare entity, moreover, extra-axial abscess concomitant with intraparenchymal purulent collections are scarcely reported in the literature. Etiology includes penetrating trauma, paranasal sinusitis, mastoiditis, craniospinal surgeries, and the rare spread of infectious agents through the hematogenous route.

Case description

We present a case of a young male with Burkholderia pseudomallei Central Nervous System (CNS) melioidosis, forming abscesses in extra-axial and intraparenchymal planes without contiguity.

Conclusion

This is to emphasize the importance of MR spectroscopy and other convenient methods in differentiating the etiology in cranial infections.

Emergence of Autochthonous Melioidosis in Two Inland PLADs - China, 2021

What is already known about this topic?

Melioidosis, a tropical infectious disease caused by Burkholderia pseudomallei (BP) infection, is endemic in the southern coastal provincial-level administrative divisions (PLADs) of China.

What is added by this report?

Three melioidosis cases, including two in young children and one in a 19-year-old female, were reported in Anhui and Jiangxi (two inland PLADs of China) respectively, in 2021. None of the patients had a travel history to a melioidosis-endemic area. All the BP isolates belonged to the same sequence type (ST51), which had been reported from elsewhere in Southeast Asia.

What are the implications for public health practice?

This is the first report of autochthonous melioidosis cases in inland Chinese PLADs. Surveillance and prevention and control work should be strengthened in this region.

Case report long segment myelitis secondary to neuro melioidosis

Background

Neuro-melioidosis, comprising 4% of all cases of melioidosis carries a risk of high morbidity and mortality. We describe two Sri Lankan patients presenting with long segment myelitis secondary to melioidosis.

Case presentation

Case 1: 47-year-old male presented with right side hemiparesis which progressed rapidly to quadriparesis. Initial cerebro spinal fluid (CSF) analysis revealed protein 76 mg/dl and glucose 72 mg/dl but without a cellular reaction. MRI spine revealed long segment myelitis with contrast enhancement. The patient was treated with intravenous methyl prednisolone pulses (IV MPP) and plasma exchanges(PLEX) on suspicion of an immune mediated myelitis but without success. A repeat MRI revealed high signal changes in the brain stem and along the entire spinal cord with contrast enhancement. MRI brain after treatment with MPP/PLEX showed enhancing hyper intensities along the corticospinal tracts. The repeat CSF revealed protein 1187 mg/dl, glucose 78 mg/dl, lymphocytes 1600/mm3 and neutrophils 10,200/mm3. CSF culture has become positive for Burkholderia pseudomallei. Serum melioidosis antibody titre was 1: 320. He was started on IV meropenem with oral cotrimoxazole for 12 weeks followed by oral co trimoxazole. But he had poor clinical recovery.

Case 2: 47-year-old female presented with bilateral lower limb weakness for 1-week duration. On examination, she had flaccid paraparesis with a sensory level at T11. Inflammatory markers were elevated. CSF analysis revealed protein 50 mg/dl with lymphocytes 172/mm3. MRI pan spine revealed a long segment myelitis. Serum melioidosis antibody titre was 1: 640. She was treated with IV meropenem for 8 weeks followed by oral co-trimoxazole with an excellent clinical and radiological response.

Conclusion

Numerous neurological manifestations have been described with melioidosis, however long segment myelitis with a positive CSF culture is not yet reported. These cases signify the importance of considering melioidosis as a differential in patients with long segment myelitis especially in endemic areas.

Imaging manifestations of pulmonary melioidosis: A case series

Melioidosis is an endemic disease in Southeast Asia and Oceania caused by the gram-negative bacillus Burkholderia pseudomallei. We studied 15 adult patients from Colombia with microbiologically diagnosed pulmonary melioidosis. We reviewed 15 chest X-rays and 10 chest computed tomography (CT) studies. Of the 15 patients, 87% met the criteria for acute infection and 13% met the criteria for chronic infection. The most common findings on chest X-rays were consolidation (86%), nodules (26%), and cavitation (20%). On CT studies, consolidation and nodules were observed in 90% of cases; the areas of consolidation were predominantly located in the basal and central zones in 60%. Areas of cavitation were observed in 50%, pleural effusion in 60%, and mediastinal lymph nodes in 30%. In patients with acute pulmonary melioidosis (n=8), the findings observed were nodules (100%), mixed pattern with nodules and consolidation (87%), pleural effusion (88%), and mediastinal lymph nodes (25%). The two patients with chronic pulmonary melioidosis both had cavitation. Acute lung infection with B. Pseudomallei has radiologic manifestations similar to those of pneumonia due to other causes. In areas where the disease is endemic, it is essential to include acute melioidosis in the differential diagnosis of pulmonary nodules and chronic melioidosis in the differential diagnosis of cavitated chronic lung lesions.

A novel lytic phage potentially effective for phage therapy against Burkholderia pseudomallei in the tropics

Background

Burkholderia pseudomallei is a tropical pathogen that causes melioidosis. Its intrinsic drug-resistance is a leading cause of treatment failure, and the few available antibiotics require prolonged use to be effective. This study aimed to assess the clinical potential of B. pseudomallei phages isolated from Hainan, China.

Methods

Burkholderia pseudomallei strain (HNBP001) was used as the isolation host, and phages were recovered from domestic environmental sources, which were submitted to the host range determination, lytic property assays, and stability tests. The best candidate was examined via the transmission electron microscope for classification. With its genome sequenced and analyzed, its protective efficacy against B. pseudomallei infection in A549 cells and Caenorhabditis elegans was evaluated, in which cell viability and survival rates were compared using the one-way ANOVA method and the log-rank test.

Results

A phage able to lyse 24/25 clinical isolates was recovered. It was classified in the Podoviridae family and was found to be amenable to propagation. Under the optimal multiplicity of infection (MOI) of 0.1, an eclipse period of around 20 min and a high titer (10¹² PFU/ml) produced within 1 h were demonstrated. This phage was found stabile at a wide range of temperatures (24, 37, 40, 50, and 60 °C) and pH values (3–12). After being designated as vB_BpP_HN01, it was fully sequenced, and the 71,398 bp linear genome, containing 93 open reading frames and a tRNA-Asn, displayed a low sequence similarity with known viruses. Additionally, protective effects of applications of vB_BpP_HN01 (MOI = 0.1 and MOI = 1) alone or in combination with antibiotics were found to improve viability of infected cells (70.6 ± 6.8%, 85.8 ± 5.7%, 91.9 ± 1.8%, and 96.8 ± 1.8%, respectively). A significantly reduced mortality (10%) and a decreased pathogen load were demonstrated in infected C. elegans following the addition of this phage.

Conclusions

As the first B. pseudomallei phage was isolated in Hainan, China, phage vB_BpP_HN01 was characterized by promising lytic property, stability, and efficiency of bacterial elimination during the in vitro/vivo experiments. Therefore, we can conclude that it is a potential alternative agent for combating melioidosis.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-022-01012-9.

Oral Melioidosis in Odontogenic Keratocyst of Mandible

Melioidosis is a potentially fatal, life-threatening infection caused by the gram-negative saprophytic organism Burkholderia. It is a disease endemic to Southeast Asia and Northern Australia. This infection transmits through direct contact, cutaneous inoculation, inhalation, or ingestion, and patients clinically exhibit abscesses in single or multiple organs. It is clinically under-reported due to a low index of suspicion, lack of diagnostic facilities, and misdiagnosis as tuberculosis. Infections of the musculoskeletal system are exceedingly rare, and clinical presentation may vary from the involvement of femoral bone, palmar tenosynovitis, and parietal bone osteomyelitis secondary to central nervous system involvement. The rarity of the melioidosis to secondarily infect a developmental odontogenic cyst leading to focal osteomyelitis of mandible prompts the clinician toward thorough evaluation for early diagnosis and treatment.

Burden of melioidosis in India and South Asia: Challenges and ways forward

Melioidosis is caused by the environmental bacterium Burkholderia pseudomallei. South Asia is estimated to have 44% of the global disease burden. Among South Asian countries, Bangladesh and Sri Lanka are considered endemic for melioidosis; a few cases have been reported from Nepal, and a few imported cases from Pakistan have also been reported. India has experienced an increase in numbers of melioidosis cases in the recent years. The bacteria is inherently present in the soil and enters the human body via skin abrasions, inhalation, or ingestion. As clinicians are often ignorant about the similar characteristics of this disease and several other common tropical diseases, it causes a major delay in the timely diagnosis and management. The organism is easily mistaken as Pseudomonas spp in microbiology laboratories and may be dismissed as a common laboratory contaminant. The poor diagnostic sensitivity of blood culture also leads to missed diagnosis. Hence, both clinical ignorance and missed laboratory diagnosis have misrepresented melioidosis as a rare entity. The key preventive interventions are avoiding contact with loose and muddy soils of meliodosis-endemic areas, and provision of safe drinking water. The present article describes the various possible attributes for melioidosis underdiagnosis and the challenges of improving the diagnosis in conjunction with viable solutions.

Funding

None.

A rare case of melioidosis presenting as myositis in Sri Lanka

Background

Melioidosis caused by Burkholderia pseudomallei is an emerging infection in Sri Lanka with a high case fatality rate. The disease usually manifests as pneumonia, however multisystem involvement is common. Myositis is an extremely rare occurrence and this is the only documented case where the initial presentation of melioidosis has been myositis and later complicated to myonecrosis.

Case presentation

A 45-year-old gentleman with pre-existing diabetes presented with a tender, right thigh lump for 1 week duration without any history of trauma or infection. Investigations revealed neutrophil leukocytosis, high erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels whilst ultrasonography showed focal myositis of right quadriceps. The patient went into sepsis amidst antibacterial treatment which warranted urgent surgery. At surgery, a large intramuscular abscess with myonecrosis was observed within vastus medialis which was completely drained and pus was taken for culture which eventually isolated Burkholderia pseudomallei. Melioidosis was diagnosed and intravenous meropenem was prescribed for 3 weeks. Following complete recovery, the patient was discharged on doxycycline and trimethoprim sulfamethoxazole for 3 months.

Conclusions

Melioidosis, an endemic disease in south east Asia and northern Australia, is an emerging infection in Sri Lanka. Myositis is a rare presentation of the disease that can lead to myonecrosis and abscess formation which can cause rapid disease escalation and sepsis. Early surgical intervention may be life-saving in such cases where antibiotic therapy alone may not suffice.

Comprehensive approaches for the detection of Burkholderia pseudomallei and diagnosis of melioidosis in human and environmental samples

Melioidosis is endemic in Southeast Asia and northern Australia. The causative agent of melioidosis is a Gram-negative bacterium, Burkholderia pseudomallei. Its invasion can be fatal if melioidosis is not treated promptly. It is intrinsically resistant to a variety of antibiotics. In this paper, we present a comprehensive overview of the current trends on melioidosis cases, treatments, B. pseudomallei virulence factors, and molecular techniques to detect the bacterium from different samples. The clinical and microbial diagnosis methods of identification and detection of B. pseudomallei are commonly used for the rapid diagnosis and typing of strains, such as polymerase chain reaction or multi-locus sequence typing. The genotyping strategies and techniques have been constantly evolving to identify genomic loci linked to or associated with this human disease. More research strategies for detecting and controlling melioidosis should be encouraged and conducted to understand the current situation. In conclusion, we review existing diagnostic methodologies for melioidosis detection and provide insights on prospective diagnostic methods for the bacterium.

Case of misdiagnosed melioidosis from Hue city, Vietnam

Melioidosis is an emerging infection, a potentially fatal tropical disease caused by Burkholderia pseudomallei in humans and animals, endemic in Southeast Asia and northern Australia. Diagnosis remains problematic due to its similarity to many other infections. The lack of clinical awareness and correct microbiological diagnosis contributes to the misidentification of melioidosis. We present a melioidosis case, which was misdiagnosed with pneumonia and septicemia due to Aeromonas salmonicida, leading to ineffective prolonged-course antibiotic treatment for the patient.

Enhanced serodiagnosis of melioidosis by indirect ELISA using the chimeric protein rGroEL-FLAG300 as an antigen

Background

The accurate and rapid diagnosis of melioidosis is challenging. Several serological approaches have been developed using recombinant antigens to improve the diagnostic indices of serological tests for melioidosis.

Methods

Fusion proteins from Burkholderia pseudomallei (rGroEL-FLAG300) were evaluated as a potential target antigen for melioidosis antibodies. A total of 220 serum samples from 38 culture proven melioidosis patients (gold standard), 126 healthy individuals from endemic (n = 37) and non-endemic (n = 89) Thai provinces and 56 patients with other proven bacterial infections as negative controls were tested using indirect enzyme-linked immunosorbent assays (ELISA).

Results

Using an optical density (OD) cut-off of 0.299148, our assay had 94.74% sensitivity (95% confidence interval (CI) = 82.3–99.4%), 95.05% specificity (95% CI = 90.8–97.7%), and 95% accuracy, which was better than in our previous work (90.48% sensitivity, 87.14% specificity, and 87.63% accuracy).

Conclusion

Our results suggest that the application of chimeric antigens in ELISA could improve the serological diagnosis of melioidosis and should be reconfirmed with greater patient numbers.

Paravertebral abscess and bloodstream infection caused by Burkholderia pseudomallei after acupuncture: a case report

Background

Various pathogenic bacterial infections caused by acupuncture have raised widespread concern, but paravertebral abscesses and bloodstream infections of Burkholderia pseudomallei (B.pseudomallei) after acupuncture have not been reported.

Case presentation

A 49-year-old man was admitted to hospital with recurrent back pain and fever for 1 month, along with the finding of undiagnosed diabetes. He was considered to have tuberculosis because of unrelieved high fever and pulmonary nodules. Bilateral blood culture suggested B.pseudomallei infection, MRI of the lumbar spine suggested paravertebral abscess, and the final diagnosis was paravertebral abscess and bloodstream infection after acupuncture combined with migrating lung infection. He was discharged after abscess debridement and intensive anti-infective therapy, but no further oral antibiotics were administered because of his poor adherence. More than 5 months later, he was readmitted with the urine culture findings of B.pseudomallei. No other abscess formation was observed and he received oral antibiotics for more than 3 months without recurrence.

Conclusions

Acupuncture may lead to B.pseudomallei infection in high-risk groups, and inadequate treatment can lead to recurrent infections.

Reliable detection of Burkholderia pseudomallei using multiple cross displacement amplification label-based biosensor

Background

Burkholderia pseudomallei (B. pseudomallei), as a highly pathogenic organism, causes melioidosis, which is a disease of public health importance in many tropical developing countries. Here, we present and validate a novel detection technique, termed multiple cross displacement amplification combined with nanoparticles-based lateral flow biosensor (MCDA-NB), for identifying B. pseudomallei and diagnosing melioidosis.

Results

B. pseudomallei-MCDA targets the TTS1 (Type III secretion system gene cluster 1) to specifically design ten MCDA primers. The nanoparticles-based biosensor (NB) can be combined with B. pseudomallei-MCDA for visually, objective, simply and rapidly reporting reaction results. The optimal amplification conditions of B. pseudomallei-MCDA were 66 °C for 30 min. Assay’s sensitivity was 100 fg of genomic DNA in the pure cultures, and the analytical specificity was 100% by the examination of 257 strains, including 228 B. pseudomallei and 29 non-B. pseudomallei. As a result, the whole detection procedure was completed within 50 min, including 15 min for genomic DNA preparation, 30 min for l MCDA reaction, and 2 min for the interpretation of the results visually by biosensor.

Conclusions

B. pseudomallei-MCDA assay is a rapid, sensitive and specific method for the detection of B. pseudomallei, and can be used as a potential tool for melioidosis diagnose in basic, field and clinical laboratories.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02485-2.

Melioidosis of the central nervous system; impact of the bimABm allele on patient presentation and outcome

BACKGROUND

The autotransporter protein Burkholderia intracellular motility A (BimA) facilitates the entry of Burkholderia pseudomallei into the central nervous system (CNS) in mouse models of melioidosis. Its role in the pathogenesis of human cases of CNS melioidosis is incompletely defined.

METHODS

Consecutive culture-confirmed cases of melioidosis at two sites in tropical Australia after 1989 were reviewed. Demographic, clinical and radiological data of the patients with CNS melioidosis were recorded. The bimA allele (bimABm or bimABp) of the B. pseudomallei isolated from each patient was determined.

RESULTS

Of the 1587 cases diagnosed at the two sites during the study period, 52 (3.3%) had confirmed CNS melioidosis; 20 (38.5%) had a brain abscess, 18 (34.6%) had encephalomyelitis, 4 (7.7%) had isolated meningitis and 10 (19.2%) had extra-meningeal disease. Among the 52 patients, there were 8 (15.4%) deaths; 17/44 (38.6%) survivors had residual disability. The bimA allele was characterized in 47/52; 17/47 (36.2%) had the bimABm allele and 30 (63.8%) had the bimABp allele. Patients with a bimABm variant were more likely to have a predominantly neurological presentation (odds ratio (OR) (95% confidence interval (CI)): 5.60 (1.52-20.61), p=0.01), to have brainstem involvement (OR (95%CI): 7.33 (1.92-27.95), p=0.004) and to have encephalomyelitis (OR (95%CI): 4.69 (1.30-16.95), p=0.02. Patients with a bimABm variant were more likely to die or have residual disability (odds ratio (95%CI): 4.88 (1.28-18.57), p=0.01).

CONCLUSIONS

The bimA allele of B. pseudomallei has a significant impact on the clinical presentation and outcome of patients with CNS melioidosis.

A recombinase polymerase amplification lateral flow assay for rapid detection of Burkholderia pseudomallei, the causative agent of melioidosis

Burkholderia pseudomallei causes a fatal and infectious disease, melioidosis or Whitmore's disease in humans and animals. Melioidosis is present in different parts of the world and is endemic in Southeast Asia and Northern Australia. Accurate diagnosis of melioidosis is difficult due to its common flu-like symptoms, potentially long incubation period and erroneous identification as culture contaminant. Early diagnosis of the disease is essentially required for administration of suitable antibiotics and disease containment. The present study reports a rapid, specific and sensitive recombinase polymerase amplification lateral flow assay for detection of B. pseudomallei. Specific primers and probe were designed and the assay was performed at 41 °C for 20 min in a portable incubator. End products were detected using ready-to-use lateral flow strips. RPA lateral flow assay could detect ≥ 250 fg genomic DNA of B. pseudomallei and ≥ 50 copies of recombinant plasmid harbouring the target DNA sequence. The assay was found to be highly specific and did not cross-react with other bacterial strains. In artificially spiked human blood and urine samples, the detection limit of the assay was 4.8 × 10⁴ and 4.95 × 10⁴ CFU/mL of B. pseudomallei, respectively. The detection limit of assay after 6 h of enrichment of artificially spiked urine samples was found to be 4.95 × 10³ CFU/mL of B. pseudomallei. Detection limit in artificially spiked tap water and soil samples was determined to be 7.5 × 10² CFU/mL and 3.3 × 10⁴ CFU per 5 g of B. pseudomallei, respectively.

Fever in a returning traveler: A case and literature review of melioidosis

Burkholderia pseudomallei is an aerobic, motile, non-spore-forming gram-negative bacillus found in tropical endemic environments that causes the disease melioidosis. Melioidosis displays a diversity of clinical presentations ranging from septic shock to chronic latent infection, often with characteristic abscesses in multiple organs. Melioidosis is an opportunistic infection, with risk factors, including diabetes, alcohol use, chronic lung disease, and chronic renal disease, and these risk factors increase the severity of disease (Wiersinga et al., 2006) [1]. In this case report, we illustrate a case of a 32 year old man with several risk factors and recent travel to an endemic region presenting with melioidosis. Our case demonstrates the challenges in obtaining a diagnosis in a non-endemic location, highlights a complex presentation of this disease, and describes the multifaceted clinical management required to care for this patient. As global travel increases, there is an increased need for clinician awareness of this disease in non-endemic regions.

Disseminated melioidosis in a patient from Nicaragua

Melioidosis is a disease caused by Burkholderia pseudomallei. Highly endemic areas include tropical Australia and Southeast Asia, though cases have been reported in the Americas. To our knowledge this is the first case to have occurred due to presumed exposure in Nicaragua, demonstrating the need for increased awareness. In addition, the severity of melioidosis also varies widely and more research is needed on the pattern of disease particularly in non-endemic regions.

Melioidosis-related mycotic aneurysm: Three cases

Background

Melioidosis-related mycotic aneurysm (MA) is rare but a potentially life-threatening disease with high morbidity and mortality rate.

Case presentation

We report a case series of mycotic aneurysm caused by Burkholderia pseudomallei and the subsequent outcomes. Here, we illustrate their clinical characteristics, laboratory results, radiological findings, mode of therapies and clinical outcomes.

Conclusion

Melioidosis-associated MA may manifest in an atypical presentation. Its outcome is often lethal if antimicrobial therapy and surgical intervention are not offered promptly.

Fine-needle aspiration to improve diagnosis of melioidosis of the head and neck in children: a study from Sarawak, Malaysia

Background

Melioidosis, the infection caused by Burkholderia pseudomallei, is associated with a high case fatality rate, due in part to difficulties in clinical recognition and diagnostic confirmation of the disease. Although head and neck involvement is common in children, specific disease manifestations differ between geographic regions. The aim of this study was to provide a detailed description of melioidosis of the head and neck among children in Sarawak, Malaysia, and determine if fine-needle aspiration of suspected head or neck lesions could improve melioidosis diagnosis.

Methods

We conducted a retrospective descriptive study of all children aged < 12 years with culture-confirmed melioidosis presenting with head and neck manifestations and admitted to Bintulu Hospital in Sarawak, Malaysia, from January 2011 until December 2020. Fine-needle aspiration of head and neck lesions suspected to be due to melioidosis with inoculation in blood culture bottles (FNA + BCB) was used from the beginning of 2016.

Results

Of 34 children with culture-confirmed melioidosis, 20 (59%) had an infection involving one or more sites in the head and neck. Of these, 17 (85%) were diagnosed in or after 2016. Cervical lymph nodes were the most common organ or site affected, involved in 19 (95%) children. Clinical presentations of B. pseudomallei lymph node infections were highly variable. Five (25%) children had salivary gland involvement. Lacrimal gland involvement (dacryocystitis) and skin or soft tissue infection (scalp abscess) were less frequent. B. pseudomallei was isolated from the head or neck using FNA + BCB in 15 (75%) children and by standard culture methods of direct plating of pus on agar following incision and drainage in only 2 (10%) children. B. pseudomallei was isolated from non-head or neck specimens or blood in 3 (15%) children.

Conclusions

Manifestations of pediatric head and neck melioidosis in Sarawak, Malaysia, differ from those of other regions. Fine-needle aspiration, mainly of affected cervical lymph nodes, facilitates B. pseudomallei detection and enables confirmation of melioidosis infections.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06754-9.

Clinico-microbiological description and evaluation of rapid lateral flow immunoassay and PCR for detection of Burkholderia pseudomallei from patients hospitalized with sepsis and pneumonia: A twenty-one months study from Odisha, India

Establishing a diagnosis of melioidosis based on clinical grounds is difficult in hospitalized patients with sepsis or community acquired pneumonia (CAP). We aimed to ascertain the prevalence, clinico-epidemiological and laboratory profile of melioidosis in hospitalized patients with sepsis or CAP, and to evaluate the diagnostic utility of rapid lateral flow immunoassay (LFI) and PCR in comparison with culture. In all patients with sepsis or CAP, blood, sputum/throat swab, and urine sample were subjected to culture along with other samples based on clinical presentation. In addition, PCR assay targeting the type III secretion system 1 (TTS1) and LFI was performed. Thirty-three (33/196, 17%) out of the total 196 cases were diagnosed as melioidosis by culture. The prevalence of melioidosis in patients who had only sepsis without CAP, had both sepsis and CAP, had CAP without sepsis was 31% (26/84), 22 % (4/18) and 3%(3/94) respectively. All the LFI or PCR positive cases were culture positive from at least one or more samples (blood/sputum/urine/pus). The sensitivity, specificity, positive predictive value and negative predictive value of TTS1 PCR was 78% (18/23 melioidosis patients), 100% (34/34 non-melioidosis patients), 100% (18/18 melioidosis patients) and 87% (34/39 non-melioidosis patients). The sensitivity, specificity, positive predictive value and negative predictive value of Rapid LFI was 91% (21/23 melioidosis patients), 100% (22/22 non-melioidosis patients), 100% (21/21 melioidosis patients) and 91% (22/24 non-melioidosis patients). On sample wise stratification of LFI and TTS1 with respect to culture, plasma/serum samples showed the highest discordance by PCR (9/55, 16.3%) and LFI (11/35, 31.4%). The lowest discordance was noted in respiratory tract samples (2/32, 6.2%) by PCR and pus/body fluids samples (2/14, 14.2%) by LFI and these findings are in line with previous published literature. The clinical utility of PCR and LFI needs to be further validated in a large scale study for early diagnosis of septicaemic melioidosis.

A multi-country study using MALDI-TOF mass spectrometry for rapid identification of Burkholderia pseudomallei

Background

Burkholderia pseudomallei is the bacterial causative agent of melioidosis, a difficult disease to diagnose clinically with high mortality if not appropriately treated. Definitive diagnosis requires isolation and identification of the organism. With the increased adoption of MALDI-TOF MS for the identification of bacteria, we established a method for rapid identification of B. pseudomallei using the Vitek MS, a system that does not currently have B. pseudomallei in its in-vitro diagnostic database.

Results

A routine direct spotting method was employed to create spectra and SuperSpectra. An initial B. pseudomallei SuperSpectrum was created at Shoklo Malaria Research Unit (SMRU) from 17 reference isolates (46 spectra). When tested, this initial SMRU SuperSpectrum was able to identify 98.2 % (54/55) of Asian isolates, but just 46.7 % (35/75) of Australian isolates. Using spectra (430) from different reference and clinical isolates, two additional SMRU SuperSpectra were created. Using the combination of all SMRU SuperSpectra with seven existing SuperSpectra from Townsville, Australia 119 (100 %) Asian isolates and 31 (100 %) Australian isolates were correctly identified. In addition, no misidentifications were obtained when using these 11 SuperSpectra when tested with 34 isolates of other bacteria including the closely related species Burkholderia thailandensis and Burkholderia cepacia.

Conclusions

This study has established a method for identification of B. pseudomallei using Vitek MS, and highlights the impact of geographical differences between strains for identification using this technique.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02276-1.

A case of renal abscess and bacteremia caused by Burkholderia pseudomallei that was first unidentifiable by matrix-assisted laser desorption ionization-time of flight mass spectrometry in a Japanese-man

Melioidosis, an infectious disease caused by Burkholderia pseudomallei, is endemic in specific regions, including Southeast Asia and Northern Australia. In Japan, where no autochthonous has been reported to date, melioidosis is a rare infectious disease. Herein, we report a case of melioidosis in a 68-year-old Japanese man with renal abscess and bacteremia, but without pneumonia. The patient presented to our hospital and was admitted for fever and chills that have persisted for two months. It was speculated that he was infected in Thailand, where his family lives because he shuttled between Thailand and Japan. Blood cultures on admission identified Burkholderia species; however, the species was unidentifiable by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Further re-examination, including culture, loop-mediated isothermal amplification, and multiplex polymerase chain reaction methods, finally identified Burkholderia pseudomallei. We treated the patient with intravenous ceftazidime for four weeks. In addition to the antibiotics administration, puncture drainage of the renal abscess was performed, and he gradually became afebrile. Intravenous ceftazidime was switched to oral sulfamethoxazole/trimethoprim on post-admission day 32, and he was discharged. After five months of oral sulfamethoxazole/trimethoprim, no recurrence was observed one year after discharge. To diagnose melioidosis, especially in non-endemic areas, a precise and thorough understanding of its epidemiology, presentation, and identification methods is necessary.

One-step, multiplex, dual-function oligonucleotide of loop-mediated isothermal amplification assay for the detection of pathogenic Burkholderia pseudomallei

This study highlights the development of a multiplex real-time loop-mediated isothermal amplification assay. The developed assay employed a dual-function oligonucleotide (DFO) which simultaneously monitors the emitted amplification signals and accelerates the amplification process. The DFO was a modification of loop primer (LP); the 5'-end and 3'-end of the LP was tagged with fluorophore and quencher, respectively. The DFO was quenched in its unbound state and fluoresces only when it anneals to the specific target during the amplification process. With the same working mechanism as LP, DFO allowed the detection of target genes in less than 1 h in a real time monitoring system. We demonstrated this detection platform with Burkholderia pseudomallei, the causative agent of melioidosis. An internal amplification control (IAC) was incorporated in the assay to rule out false negative result and to demonstrate that the assay was successfully developed in a multiplex system. The assay was 100% specific when it was evaluated against 96 B. pseudomallei clinical isolates and 48 other bacteria species. The detection limit (sensitivity) of the developed assay was 1 fg/μl of B. pseudomallei genomic DNA and 18.2 CFU/ml at the bacterial cell level. In spiked blood samples, the assay's detection limit was 14 CFU/ml. The assay's diagnostic evaluation showed 100% diagnostic sensitivity, diagnostic specificity, positive predictive value, and negative predictive value. An integrated multiplex LAMP and real-time monitoring system was successfully developed, simplifying the workflow for the rapid and specific nucleic acid diagnostic test.

Imaging manifestations of pulmonary melioidosis: a case series

Melioidosis is an endemic disease in Southeast Asia and Oceania caused by the gram-negative bacillus Burkholderia pseudomallei. We studied 15 adult patients from Colombia with microbiologically diagnosed pulmonary melioidosis. We reviewed 15 chest X-rays and 10 chest computed tomography (CT) studies. Of the 15 patients, 87% met the criteria for acute infection and 13% met the criteria for chronic infection. The most common findings on chest X-rays were consolidation (86%), nodules (26%), and cavitation (20%). On CT studies, consolidation and nodules were observed in 90% of cases; the areas of consolidation were predominantly located in the basal and central zones in 60%. Areas of cavitation were observed in 50%, pleural effusion in 60%, and mediastinal lymph nodes in 30%. In patients with acute pulmonary melioidosis (n=8), the findings observed were nodules (100%), mixed pattern with nodules and consolidation (87%), pleural effusion (88%), and mediastinal lymph nodes (25%). The two patients with chronic pulmonary melioidosis both had cavitation. Acute lung infection with B. Pseudomallei has radiologic manifestations similar to those of pneumonia due to other causes. In areas where the disease is endemic, it is essential to include acute melioidosis in the differential diagnosis of pulmonary nodules and chronic melioidosis in the differential diagnosis of cavitated chronic lung lesions.

Aortic endograft infection secondary to Burkholderia pseudomallei: A case report and review of the literature

Aortic graft infection is a rare complication after endovascular aneurysm repair that is usually caused by gram-positive organisms such as Staphylococcus spp or gram-negative organisms such as Enterobacteriaceae or Salmonella spp. We have presented a unique case of a patient with acute graft infection secondary to Burkholderia pseudomallei. Because treatment of B. pseudomallei infections is challenging owing to its inherent resistance to multiple antibiotics, we have proposed an approach for managing similar cases in the future. Lifestyle advice on avoiding soil exposure in the postoperative period after endovascular aneurysm repair might be an important preventative measure in endemic regions.