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The soil bacterium Burkholderia pseudomallei causes melioidosis, a potentially fatal and greatly underdiagnosed tropical disease. Detection of B. pseudomallei in the environment is important to trace the source of infections, define risk areas for melioidosis and increase the clinical awareness. Although B. pseudomallei polymerase chain reaction (PCR)-based environmental detection provides important information, the culture of the pathogen remains essential but is still a methodological challenge. B. pseudomallei can catabolize erythritol, a metabolic pathway, which is otherwise rarely encountered among bacteria. We recently demonstrated that replacing threonine with erythritol as a single carbon source in the pH-neutral threonine-basal salt solution (TBSS-C50) historically used improved the isolation of B. pseudomallei from rice paddy soils. However, further culture medium parameters for an optimized recovery of B. pseudomallei strains from soils are still ill-defined. We, therefore, aimed to design a new erythritolbased medium by systematically optimizing parameters such as pH, buffer capacity, salt and nutrient composition. A key finding of our study is the enhanced erythritol-based growth of B. pseudomallei under acidic medium conditions. Our experiments with B. pseudomallei strains from different geographical origin led to the development of a phosphate-buffered acidic erythritol (ACER) medium with a pH of 6.3, higher erythritol concentration of 1.2%, supplemented vitamins and nitrate. This highly selective medium composition shortened the lag phase of B. pseudomallei cultures and greatly increased growth densities compared to TBSS-C50 and TBSS-C50-based erythritol medium. The ACER medium led to the highest enrichments of B. pseudomallei as determined from culture supernatants by quantitative PCR in a comparative validation with soil samples from the central part of Vietnam. Consequently, the median recovery of B. pseudomallei colony forming units on Ashdown's agar from ACER subcultures was 5.4 times higher compared to TBSS-C50-based erythritol medium (p = 0.005) and 30.7 times higher than TBSS-C50 (p < 0.001). In conclusion, our newly developed ACER medium significantly improves the isolation of viable B. pseudomallei from soils and, thereby, has the potential to reduce the rate of false-negative environmental cultures in melioidosis risk areas. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objectives: Objectives: Gram-negative pathogenic bacterium Burkholderia pseudomallei is the causative organism of melioidosis, predominantly reported in Southeast Asia. The infections in humans can be recurrent, and sometimes difficult to cure. Studying the genome of B. pseudomallei is the key to understand origins, transmission routes, and phylogenetic relationships. Methods: We compared all available B. pseudomallei genomes from the NCBI database representing Sri Lanka to 15 previously reported genomes in Asia. The analysis involved in silico MLST, wgMLST, single nucleotide polymorphism (SNP), average nucleotide identity (ANI), clonal complexes (CC), virulence, and antibiotic resistance profiles. Results: The MLST analyses of 24 strains revealed, 6 Sri Lankan and 1 Indian strain formed CC594*, a novel single locus variant clonal complex, and 3 strains from Malaysia, Vietnam, Thailand formed another clonal complex named CC70*. From 9 Sri Lankan strains, BPs122 and BPs133 had ancestral origins tied to BPs114 with 114/99.6% and 140/99.6% for SNPs/ANIs. In CC70*, Thailand and Vietnam strains had 1196/99.95% for SNPs/ANIs, respectively. Among the Sri Lankan strains, TIN-based motility gene bimA detected in BPs110 only, whereas LPS antigen was presented in BPs112, BPs115, and BPs116 genomes. A total of 67 genes related to antibiotic resistance (22 multidrug efflux systems, 10 regulators modulating/expression of antibiotic resistance, and 11 antibiotic inactivation enzymes related genes) were identified. Conclusion: The B. pseudomallei strains in Sri Lanka represent a highly diverse nature and some of them had clonal relationships with other Asian strains. The present study concludes B. pseudomallei strains in Sri Lanka have probably risen from different ancestral origins. [ABSTRACT FROM AUTHOR]

Background: The epidemiology of melioidosis in Vietnam, a disease caused by the soil bacterium Burkholderia pseudomallei, remains unclear. This study aimed to detect paediatric melioidosis in South Vietnam and describe clinical features and the geographic distribution., Methods: We introduced a simple laboratory algorithm for detecting B. pseudomallei from clinical samples at Children's Hospital 2 in Ho Chi Minh City in July 2015. A retrospective observational study of children <16 y of age with culture-confirmed melioidosis between July 2015 and August 2019 was undertaken., Results: Thirty-five paediatric cases of melioidosis were detected, with cases originating from 13 of 32 provinces and cities in South Vietnam. The number of paediatric melioidosis cases detected from a certain region correlated with the overall number of inpatients originating from the respective geographic area. Suppurative parotitis (n=15 [42.8%]) was the most common clinical presentation, followed by lung infection (n=10 [28.6%]) and septicaemia (n=7 [20%]). Fourteen (40%) children had disseminated disease, including all cases of lung infection, four cases with central nervous system symptoms and four (11.4%) deaths., Conclusions: The patients' origin indicates a wide distribution of melioidosis in South Vietnam. It seems probable that cases not only in children, but also in adults, remain grossly undiagnosed. Further awareness raising and laboratory capacity strengthening are needed in this part of the country., (© The Author(s) 2023. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.)

Isolation of the soil bacterium Burkholderia pseudomallei from tropical environments is important to generate a global risk map for man and animals to acquire the infectious disease melioidosis. There is increasing evidence, that the currently recommended soil culture protocol using threonine-basal salt solution with colistin (TBSS-C50) for enrichment of B. pseudomallei and Ashdown agar for subsequent subculture lacks sensitivity. We therefore investigated, if the otherwise rarely encountered erythritol catabolism of B. pseudomallei might be exploited to improve isolation of this bacterium from soil. Based on TBSS-C50, we designed a new colistin-containing medium with erythritol as the single carbon source (EM). This medium was validated in various culture protocols by analyzing 80 soil samples from 16 different rice fields in Vietnam. B. pseudomallei enrichment was determined in all culture supernatants by a specific quantitative PCR (qPCR) targeting the type three secretion system 1. 51 out of 80 (63.8%) soil samples gave a positive qPCR signal in at least one of the culture conditions. We observed a significantly higher enrichment shown by lower median cycle threshold values for B. pseudomallei in a two-step culture with TBSS-C50 for 48 h followed by EM for 96h compared to single cultures in TBSS-C50 for either 48h or 144h (p<0.0001, respectively). Accordingly, B. pseudomallei could be isolated on Ashdown agar in 58.8% (30/51) of samples after subcultures from our novel two-step enrichment culture compared to only 9.8% (5/51) after standard enrichment with TBSS-C50 for 48h (p<0.0001) or 25.5% (13/51; p<0.01) after TBSS-C50 for 144h. In the present study, we show that specific exploitation of B. pseudomallei metabolic capabilities in enrichment protocols leads to a significantly improved isolation rate of this pathogen from soil compared to established standard procedures. Our new culture method might help to facilitate the creation of environmental risk maps for melioidosis in the future. Melioidosis is a vastly underdiagnosed infectious disease caused by the bacterial soil pathogen B. pseudomallei. Global environmental suitability for B. pseudomallei has recently been predicted to cover huge areas with three billion people potentially at risk to acquire infection. Although sensitive as well as specific molecular methods are available, cultural isolation of B. pseudomallei strains from the environment will be indispensable to verify this prediction in potential endemic, low-income countries and is a prerequisite to assess the virulence potential and genetic diversity of strains. The currently applied cultural detection lacks sensitivity, which is at least partly due to a lack in selectivity allowing other highly abundant soil microorganisms to outcompete B. pseudomallei. We therefore aimed to develop a more selective medium by taking advantage of B. pseudomallei erythritol catabolism, a metabolic pathway, which is not commonly encountered in other related bacteria. Validation of our new medium with erythritol as the single carbon source was performed by molecular and cultural detection using soil samples from rice paddies in Vietnam. We observed an enhanced enrichment and selectivity resulting in the isolation of B. pseudomallei strains from soil samples, which were otherwise culture-negative when tested by the standard method. [ABSTRACT FROM AUTHOR]

Background: Bloodstream infections (BSIs) are associated with high morbidity and mortality worldwide. However their aetiology, antimicrobial susceptibilities and associated outcomes differ between developed and developing countries. Systematic data from Vietnam are scarce. Here we present aetiologic data on BSI in adults admitted to a large tertiary referral hospital for infectious diseases in Hanoi, Vietnam.Methods: A retrospective study was conducted at the National Hospital for Tropical Diseases between January 2011 and December 2013. Cases of BSI were determined from records in the microbiology department. Case records were obtained where possible and clinical findings, treatment and outcome were recorded. BSI were classified as community acquired if the blood sample was drawn ≤48 h after hospitalization or hospital acquired if >48 h.Results: A total of 738 patients with BSI were included for microbiological analysis. The predominant pathogens were: Klebsiella pneumoniae (17.5%), Escherichia coli (17.3%), Staphylococcus aureus (14.9%), Stenotrophomonas maltophilia (9.6%) and Streptococcus suis (7.6%). The overall proportion of extended spectrum beta-lactamase (ESBL) production among Enterobacteriaceae was 25.1% (67/267 isolates) and of methicillin-resistance in S. aureus (MRSA) 37% (40/108). Clinical data was retrieved for 477 (64.6%) patients; median age was 48 years (IQR 36-60) with 27.7% female. The overall case fatality rate was 28.9% and the highest case fatality was associated with Enterobacteriaceae BSI (34.7%) which accounted for 61.6% of all BSI fatalities.Conclusions: Enterobacteriaceae (predominantly K. pneumoniae and E. coli) are the most common cause of both community and hospital acquired bloodstream infections in a tertiary referral clinic in northern Vietnam. [ABSTRACT FROM AUTHOR]

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The article describes two related cases of suppurative cervical lymphadenitis, an unusual adult presentation of melioidosis, in two men who returned to France from Vietnam on the same trip. It says that melioidosis is a potentially fatal infectious disease which occurs predominantly across much of Asia and in northern Australia due to soil and water bacterium Burkholderia pseudomallei.

Within 8 months, 3 children from 1 family in northern Vietnam died from melioidosis. Burkholderia pseudomallei of the same sequence type, 541, was isolated from clinical samples, borehole water, and garden and rice field soil. Boreholes should be properly constructed and maintained to avoid B. pseudomallei contamination.

(1) Background: Burkholderia pseudomallei is an environmentally mediated saprophytic pathogen that can cause severe disease in humans. It is well known that B. pseudomallei survives in tropical moist soil environments worldwide, but melioidosis is gaining recognition as a public and veterinary health issue in Vietnam. The contribution of animals to human disease is unknown, necessitating further investigation. (2) Methods: Swine sera were collected from two populations, one grazing and one commercially farmed, from three provinces in Vietnam. ELISAs utilizing B. pseudomallei capsular polysaccharide (CPS), outer polysaccharide (OPS), and Hcp1 protein were used to screen serum samples. Positive samples were mapped to the commune level. Seroprevalence calculations and pig population estimates were used to approximate number of swine exposures per commune. (3) Results: Grazing pigs from Hoa Binh had significantly higher seropositivity levels (11.4%, 95% CI: 9.7-13.1) compared to farmed pigs from Ha Tinh and Nghe An (4%, 95% CI: 3.3-4.7). Average swine seropositivity rates were ~6.3% (95% CI: 5-7.9), higher than previously identified in Vietnam (~0.88%). (4) Conclusions: Initial serological sampling identified a significant number of seropositive and potential melioidosis infections occurring in swine in Vietnam. This work is a critical step in understanding the role swine may play in the epidemiology of human melioidosis in Vietnam.

Objectives: The antimicrobial susceptibility pattern of clinical Burkholderia pseudomallei (B. pseudomallei) in Vietnam has not been reported since the first publication in 2008. The present study aimed to determine the antimicrobial susceptibility pattern of B. pseudomallei isolated in a tertiary referral centre in Hanoi from January 2012 to December 2017., Methods: A total of 312 B. pseudomallei isolates obtained from melioidosis patients admitted to a 2000-bed general hospital were analysed by the Etest method. Interpretation of the susceptibility testing results were reported using Clinical and Laboratory Standards Institute guidelines., Results: All isolates were susceptible to ceftazidime, imipenem and amoxicillin-clavulanate (100%) with MIC 90s relatively low (2μg/mL). Two isolates had intermediate resistance to doxycycline (0.6%) and 34 isolates were resistant to trimethoprim/sulfamethoxazole (10.9%)., Conclusion: The results of this study suggest that currently recommended antibiotics for melioidosis treatment can be empirically used, but continuously monitoring antimicrobial susceptibility should be a concern., (Copyright © 2019 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.)