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Fulltext Detection of spleen abscesses facilitates diagnosis of melioidosis in Malaysian children

Mohan A, Manan K, Tan LS, Tan YC, Chin ST, Ahmad R, et al.

Int J Infect Dis, 2020 Sep;98:59-66.
PMID: 32535300 DOI: 10.1016/j.ijid.2020.06.025

OBJECTIVES: Melioidosis is associated with extremely high case fatality ratios. The aim of this study was to determine whether detection of abdominal visceral abscesses can facilitate diagnosis of melioidosis in children.
METHODS: We conducted a retrospective analysis of all children who had liver and/or spleen abscesses on abdominal ultrasonography admitted to Bintulu Hospital in Sarawak, Malaysia, from January 2014 until December 2018.
RESULTS: Fifty-three children had liver and/or spleen abscesses. Spleen abscesses were present in 48 (91%) cases; liver abscesses in 15 (28%). Melioidosis was confirmed by culture in 9 (17%) children; small occult splenic abscesses were present in all cases. In 78% of these cases, the lesions were detected before any positive culture (or serology) results were available. Four (8%) children had bacteriologically-confirmed tuberculosis. Two (4%) had Staphylococcus aureus infection. Of the remaining 38 (72%) culture-negative cases, 36 (95%) had clinical and imaging characteristics similar to that of children with culture-confirmed melioidosis and improved with empirical melioidosis antibiotic therapy.
CONCLUSIONS: A large number of children in Bintulu Hospital in Sarawak, Malaysia, were found to have spleen abscesses. Melioidosis was the most common etiology identified in these children. Abdominal ultrasonography is extremely useful in facilitating the diagnosis of pediatric melioidosis.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext Disseminated melioidosis in early pregnancy - an unproven cause of foetal loss

Chang CY, Lau NLJ, Currie BJ, Podin Y

BMC Infect Dis, 2020 Mar 06;20(1):201.
PMID: 32143598 DOI: 10.1186/s12879-020-4937-8

BACKGROUND: Melioidosis is a potentially life-threatening infection caused by the Gram-negative bacterium Burkholderia pseudomallei. Melioidosis is difficult to diagnose due to its diverse clinical manifestations, which often delays administration of appropriate antibiotic therapy.
CASE PRESENTATION: Melioidosis is uncommon in pregnancy but both spontaneous abortion and neonatal melioidosis have been reported. We report a case of bacteraemic melioidosis in a young woman with a subsequent spontaneous abortion, with B. pseudomallei cultured from a high vaginal swab as well as blood.
CONCLUSION: It remains unclear in this and previously reported cases as to whether the maternal melioidosis was sexually transmitted.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext Burkholderia pseudomallei Detection among Hospitalized Patients, Sarawak

Choi JY, Hii KC, Bailey ES, Chuang JY, Tang WY, Yuen Wong EK, et al.

Am J Trop Med Hyg, 2020 02;102(2):388-391.
PMID: 31769397 DOI: 10.4269/ajtmh.19-0625

Burkholderia pseudomallei infections are prevalent in Southeast Asia and northern Australia and often misdiagnosed. Diagnostics are often neither sensitive nor rapid, contributing up to 50% mortality rate. In this 2018 pilot study, we enrolled 100 patients aged 6 months-79 years from Kapit Hospital in Sarawak, Malaysia, with symptoms of B. pseudomallei infection. We used three different methods for the detection of B. pseudomallei: a real-time polymerase chain reaction (PCR) assay, a rapid lateral flow immunoassay, and the standard-of-care bacterial culture-the gold standard. Among the 100 participants, 24 (24%) were positive for B. pseudomallei by one or more of the detection methods. Comparing the two individual diagnostic methods against the gold standard-bacterial culture-of any positive test, there was low sensitivity for each test (25-44%) but high specificity (93-98%). It seems clear that more sensitive diagnostics or a sensitive screening diagnostic followed by specific confirmatory diagnostic is needed for this disease.

Matched MeSH terms: Melioidosis/diagnosis*
Selective media and real-time PCR improves diagnosis of melioidosis in community-acquired pneumonia in a low-incidence setting in Kuala Lumpur, Malaysia

Subakir H, Chong YM, Chan YF, Hasan MS, Jamaluddin MFH, Pang YK, et al.

J Med Microbiol, 2020 Jan;69(1):49-51.
PMID: 31750812 DOI: 10.1099/jmm.0.001108

Introduction.Burkholderia pseudomallei (melioidosis) is an important cause of community-acquired pneumonia (CAP) in the tropics. Selective medium is recommended for laboratory diagnosis with non-sterile respiratory samples, while PCR is not routinely used due to variable reported performance. The effectiveness of these diagnostic modalities varies by site.Aim. To compare selective media and real-time PCR (qPCR) with routine media in detecting B. pseudomallei in CAP respiratory samples in a low-incidence setting in Kuala Lumpur, Malaysia.Methodology. Respiratory samples were routinely cultured on blood, chocolate and MacConkey agar (RESP-ROUTINE), and compared to culture on selective Ashdown medium (RESP-SELECTIVE) and qPCR. The gold standard was routine culture of B. pseudomallei from any site (ALL-ROUTINE).Results.B. pseudomallei was detected in 8/204 (3.9 %) samples. Overall sensitivity rates differed (P=0.03) for qPCR (100%), RESP-SELECTIVE (87.5%) and RESP-ROUTINE (50%). There was a trend towards lower median days to positive culture for RESP-SELECTIVE (1 day) compared to RESP-ROUTINE (2 days, P=0.08) and ALL-ROUTINE (2 days, P=0.06). Reagent costs for each additional detection were USD59 for RESP-SELECTIVE and USD354 for PCR.Conclusions. In a low-incidence setting, selective culture of respiratory samples on Ashdown was more sensitive and allowed quicker identification than routine media, at reasonable cost. Blood cultures are critical, confirming four cases missed by routine respiratory culture. Selective medium is useful in early pneumonia (pre-sepsis) and resource-limited settings where blood cultures are infrequently done. Real-time PCR is costly, but highly sensitive and useful for high-risk patients with diabetes, cancer or immunosuppressants, or requiring ventilation or intensive care.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext Systemic lupus erythematosus and melioidosis

Che Rahim MJ, Mohammad N, Kamaruddin MI, Wan Ghazali WS

BMJ Case Rep, 2019 Jul 01;12(7).
PMID: 31266760 DOI: 10.1136/bcr-2019-229974

We reported a case of a young female patient presented with sepsis and diagnosed with melioidosis and systemic lupus erythematosus (SLE) within the same admission. She presented with 1-week history of productive cough, progressive dyspnoea together with prolonged fever, arthralgia, rashes and oral ulcers. She had septicemic shock, respiratory failure requiring intubation and ventilation in intensive care unit and subsequently developed acute renal failure requiring haemodialysis. Antibiotics and immunosuppressive treatment including low-dose intravenous cyclophosphamide were commenced. She had a remarkable recovery and was discharged after 6 weeks. There was no evidence of active SLE or relapse of melioidosis during clinic follow-ups.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext Infected aneurysm after returning from Southeast Asia: think Burkholderia pseudomallei!

Auvens C, Neuwirth C, Piroth L, Blot M

BMJ Case Rep, 2019 May 22;12(5).
PMID: 31122956 DOI: 10.1136/bcr-2018-228856

Melioidosis is a protean disease which is endemic to Southeast Asia and northern Australia. Here, we report a case of infected aortic aneurysm due to Burkholderia pseudomallei in an immunocompetent man 6 months after a trip to northern Malaysia. This patient initially received inappropriate surgical and antibiotic treatment, leading to a peri-prosthetic aortic infection with lumbar spondylitis and contiguous psoas muscle abscess. This case highlights the difficulty of diagnosing melioidosis given its diverse clinical manifestations and the limits of routine microbiological methods to identify B. pseudomallei Melioidosis should be considered a possible diagnosis in individuals with unexplained fever subsequent to travel in an endemic area.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext Melioidosis in Colombia, description of a clinical case and epidemiological considerations

Rodríguez JY, Álvarez-Moreno CA, Cortés JA, Rodríguez GJ, Esquea K, Pinzón H, et al.

Biomedica, 2019 05 01;39:10-18.
PMID: 31529845 DOI: 10.7705/biomedica.v39i3.4534

Melioidosis is an infectious disease caused by Burkholderia pseudomallei whose clinical diagnosis can be difficult due not only to its varied clinical presentation but also to the difficulties in the microbiological diagnosis.Thus, it may be necessary to use molecular techniques for its proper identification once it is suspected.
There are few antibiotics available for the treatment of this disease, which must be used over a long period of time. Although it is known to be endemic in Thailand, Malaysia, Singapore, Vietnam, and Australia, in Colombia there are few reported cases.
We describe a case of melioidosis in the northern region of Colombia. Additionally, we review its clinical characteristics and treatment and we describe the local epidemiology of this disease.

Matched MeSH terms: Melioidosis/diagnosis
Melioidosis mimicking miliary tuberculosis

Tan RZ, Mohd Nor F, Shafie S, Tan LJ

Forensic Sci Med Pathol, 2019 03;15(1):151-154.
PMID: 30293222 DOI: 10.1007/s12024-018-0026-3

Melioidosis is an infectious disease caused by Burkholderia pseudomallei, a gram-negative intracellular bacillus. Tuberculosis, also an infectious disease, is caused by Mycobacterium tuberculosis, an acid fast bacillus. In both diseases, patients commonly present with fever and respiratory symptoms due to sepsis which might lead to respiratory failure or sudden death if left untreated. Not only are these two entities similar in clinical presentation, but the autopsy findings may mimic each other, giving rise to difficulties in determining the cause of death. We report a case of melioidosis and compare it to a typical case of miliary tuberculosis. Similarities between the cases on gross and histopathological examinations are discussed. In such circumstances, microbiological culture of bodily fluids and internal organs should be performed to ascertain the correct cause of death.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext Melioidosis: misdiagnosed in Nepal

Shrestha N, Adhikari M, Pant V, Baral S, Shrestha A, Basnyat B, et al.

BMC Infect Dis, 2019 Feb 19;19(1):176.
PMID: 30782129 DOI: 10.1186/s12879-019-3793-x

BACKGROUND: Melioidosis is a life-threatening infectious disease that is caused by gram negative bacteria Burkholderia pseudomallei. This bacteria occurs as an environmental saprophyte typically in endemic regions of south-east Asia and northern Australia. Therefore, patients with melioidosis are at high risk of being misdiagnosed and/or under-diagnosed in South Asia.
CASE PRESENTATION: Here, we report two cases of melioidosis from Nepal. Both of them were diabetic male who presented themselves with fever, multiple abscesses and developed sepsis. They were treated with multiple antimicrobial agents including antitubercular drugs before being correctly diagnosed as melioidosis. Consistent with this, both patients were farmer by occupation and also reported travelling to Malaysia in the past. The diagnosis was made consequent to the isolation of B. pseudomallei from pus samples. Accordingly, they were managed with intravenous meropenem followed by oral doxycycline and cotrimoxazole.
CONCLUSION: The case reports raise serious concern over the existing unawareness of melioidosis in Nepal. Both of the cases were left undiagnosed for a long time. Therefore, clinicians need to keep a high index of suspicion while encountering similar cases. Especially diabetic-farmers who present with fever and sepsis and do not respond to antibiotics easily may turn out to be yet another case of melioidosis. Ascertaining the travel history and occupational history is of utmost significance. In addition, the microbiologist should be trained to correctly identify B. pseudomallei as it is often confused for other Burkholderia species. The organism responds only to specific antibiotics; therefore, correct and timely diagnosis becomes crucial for better outcomes.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext Relapse of chronic melioidosis in a paediatric cystic fibrosis patient: first case report from Malaysia

Mariappan V, Thavagnanam S, Vellasamy KM, Teh CJS, Atiya N, Ponnampalavanar S, et al.

BMC Infect Dis, 2018 Sep 05;18(1):455.
PMID: 30185168 DOI: 10.1186/s12879-018-3371-7

BACKGROUND: Burkholderia pseudomallei is the causative agent of melioidosis, which is a potentially life threatening disease endemic in Southeast Asian countries. In Malaysia, cystic fibrosis (CF) is an uncommon condition. The association between CF and B.pseudomallei infections has been reported previously. However, this is the first case report of a pediatric melioidosis relapse and co-infection with other Gram-negative bacteria in Malaysia.
CASE PRESENTATION: A 14-year-old Chinese Malaysian boy presented with a history of recurrent pneumonia, poor growth and steatorrhoea since childhood, and was diagnosed with CF. B. pseudomallei was cultured from his sputum during three different admissions between 2013 and 2016. However, the patient succumbed to end stage of respiratory failure in 2017 despite antibiotics treatment against B.pseudomallei. The isolates were compared using multilocus-sequence typing and repetitive-element polymerase chain reaction (PCR), and confirmed that two of the isolates were of same sequence type, which may indicate relapse.
CONCLUSIONS: CF patients should be aware of melioidosis in endemic regions, as it is an emerging infectious disease, especially when persistent or recurrent respiratory symptoms and signs of infection occur. The high prevalence rates of melioidosis in Malaysia warrants better management options to improve quality of life, and life expectancy in patients with CF. Travel activities to endemic regions should also be given more consideration, as this would be crucial to identify and initiate appropriate empiric treatment.

Matched MeSH terms: Melioidosis/diagnosis*
A Case of Constrictive Pericarditis Associated with Melioidosis in an Immunocompetent Patient Treated by Pericardiectomy

Lu HT, Ramsamy G, Lee CY, Syed Hamid SRG, Kan FK, Nordin RB

Am J Case Rep, 2018 Mar 19;19:314-319.
PMID: 29551765

BACKGROUND Melioidosis is a rare tropical bacterial infection caused by the Gram-negative soil saprophyte, Burkholderia pseudomallei. Melioidosis can mimic a variety of diseases due to its varied presentation, and unless it is treated rapidly, it can be fatal. A rare case of melioidosis, with pericarditis and pericardial effusion, is described, which demonstrates the value of early diagnosis with echocardiography and pericardiocentesis. CASE REPORT A 38-year-old native (Iban) East Malaysian man presented with shortness of breath and tachycardia. Transthoracic echocardiography (TTE) showed cardiac tamponade. Urgent pericardiocentesis drained a large amount of purulent pericardial fluid that grew Burkholderia pseudomallei. Despite appropriate dose and duration of intravenous treatment with ceftazidime followed by meropenem, the patient developed recurrent pericardial effusion and right heart failure due to constrictive pericarditis. The diagnosis of constrictive pericarditis was confirmed by computed tomography (CT) and surgical exploration. Following pericardiectomy, his symptoms resolved, but patient follow-up was recommended for possible sequelae of constrictive pericarditis. CONCLUSIONS After the onset of melioidosis pericarditis, the authors recommend follow-up and surveillance for possible complication of constrictive pericarditis.

Matched MeSH terms: Melioidosis/diagnosis
Fulltext Comparison of in-house IgM and IgG ELISAs for the serodiagnosis of melioidosis in Malaysia

Hii SYF, Ali NA, Ahmad N, Amran F

J Med Microbiol, 2017 Nov;66(11):1623-1627.
PMID: 29048275 DOI: 10.1099/jmm.0.000611

Melioidosis is an endemic infectious disease in Southeast Asia and northern Australia, caused by Burkholderia pseudomallei. However, the incidence rate in Malaysia is not well documented. The high mortality rate and broad range of clinical presentations require rapid and accurate diagnosis for appropriate treatment. This study compared the efficacy of in-house IgM and IgG ELISA methods using a local B. pseudomallei strain. The diagnostic accuracy of the in-house IgG ELISA was better than that of the IgM ELISA: sensitivity (IgG: 84.71 %, IgM: 76.14 %) and specificity (IgG: 93.64 %, IgM: 90.17 %); positive predictive value (IgG: 86.75 %, IgM: 79.76 %) and negative predictive value (IgG: 92.57 %, IgM: 89.66 %); likelihood ratio (LR) [IgG: 13.32, IgM: 7.75 (LR+); IgG: 0.16, IgM: 0.26 (LR-)], and was supported by the observation of the absorbance value in comparisons between culture and serology sampling. In-house IgG ELISA was shown to be useful as an early diagnostic tool for melioidosis.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext Honeycomb and necklace signs in liver abscesses secondary to melioidosis

Ong SCL, Alemam MMM, Zakaria NA, Abdul Halim NA

BMJ Case Rep, 2017 Oct 19;2017.
PMID: 29054959 DOI: 10.1136/bcr-2017-222342

Melioidosis is endemic in Southeast Asia and tropical Australia with varying clinical features from benign skin lesions to fatal septicaemia. Imaging plays an important role in evaluation of the melioid liver abscesses. A 45-year-old man with underlying diabetes presented with fever and lethargy for 2 weeks and abdominal pain for 2 days. His liver was enlarged on examination. Blood investigations revealed mild leucocytosis and raised liver enzymes. Ultrasound showed multiple multiloculated hypoechoic lesions throughout the liver and spleen. CT of abdomen confirmed that some liver lesions were made up of asymmetric locules of varying sizes (honeycomb sign), while others had hypodense centre with small symmetric peripheral locules in radial fashion (necklace sign). Blood culture was positive for Burkholderia pseudomallei He was subsequently treated with ceftazidime for a month followed by oral trimethoprim-sulfamethoxazole for 3 months. Follow-up CT of abdomen a month after diagnosis and treatment showed resolving hepatic and splenic lesions.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext Melioidosis: Clinical impact and public health threat in the tropics

Perumal Samy R, Stiles BG, Sethi G, Lim LHK

PLoS Negl Trop Dis, 2017 May;11(5):e0004738.
PMID: 28493905 DOI: 10.1371/journal.pntd.0004738

This review briefly summarizes the geographical distribution and clinical impact of melioidosis, especially in the tropics. Burkholderia pseudomallei (a gram-negative bacterium) is the major causative agent for melioidosis, which is prevalent in Singapore, Malaysia, Thailand, Vietnam, and Northern Australia. Melioidosis patients are increasingly being recognized in other parts of the world. The bacteria are intrinsically resistant to many antimicrobial agents, but prolonged treatment, especially with combinations of antibiotics, may be effective. Despite therapy, the overall case fatality rate of septicemia in melioidosis remains significantly high. Intracellular survival of the bacteria within macrophages may progress to chronic infections, and about 10% of patients suffer relapses. In the coming decades, melioidosis will increasingly afflict travelers throughout many global regions. Clinicians managing travelers returning from the subtropics or tropics with severe pneumonia or septicemia should consider acute melioidosis as a differential diagnosis. Patients with open skin wounds, diabetes, or chronic renal disease are at higher risk for melioidosis and should avoid direct contact with soil and standing water in endemic regions. Furthermore, there are fears that B. pseudomallei may be used as a biological weapon. Technological advancements in molecular diagnostics and antibiotic therapy are improving the disease outcomes in endemic areas throughout Asia. Research and development efforts on vaccine candidates against melioidosis are ongoing.

Matched MeSH terms: Melioidosis/diagnosis
Fulltext Molecular detection of leptospirosis and melioidosis co-infection: A case report

Mohd Ali MR, Mohamad Safiee AW, Thangarajah P, Fauzi MH, Muhd Besari A, Ismail N, et al.

J Infect Public Health, 2017 Nov-Dec;10(6):894-896.
PMID: 28330585 DOI: 10.1016/j.jiph.2017.02.009

Leptospirosis and melioidosis are important tropical infections caused by Leptospira and Burkholdheria pseudomallei, respectively. As both infections share similar clinical manifestations yet require different managements, complementary laboratory tests are crucial for the diagnosis. We describe a case of Leptospira and B. pseudomallei co-infection in a diabetic 40-year-old woman with history of visit to a freshwater camping site in northern Malaysia. To our knowledge, this is the first case of such double-infection, simultaneously demonstrated by molecular approach. This case highlights the possibility of leptospirosis and melioidosis co-infections and their underlying challenges in the rapid and accurate detection of the etiologic microorganism.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext An imported case of acute melioidosis caused by ST881 Burkholderia pseudomallei

Zong Z, Wang X, Deng Y

Southeast Asian J. Trop. Med. Public Health, 2016 Mar;47(2):219-22.
PMID: 27244959

A previously healthy Chinese male working in Malaysia returned to China with high fever. A blood culture showed Burkholderia pseudomallei strain WCBP1. This isolate was sequenced, showing type, ST881, which appears to be present in Malaysia. WCP1 had unusual susceptibility to aminoglycosides and habored the Yersinia-like fimbrial gene cluster for virulence. The patient's condition deteriorated rapidly but he recovered after receiving meropenem and intensive care support. Melioidosis is a potential problem among Chinese imigrant workers with strains new to China being identified.

Matched MeSH terms: Melioidosis/diagnosis*
Transcriptome analysis of Burkholderia pseudomallei T6SS identifies Hcp1 as a potential serodiagnostic marker

Chieng S, Mohamed R, Nathan S

Microb Pathog, 2015 Feb;79:47-56.
PMID: 25616255 DOI: 10.1016/j.micpath.2015.01.006

Burkholderia pseudomallei, the causative agent of melioidosis, is able to survive extreme environments and utilizes various virulence factors for survival and pathogenicity. To compete and survive within these different ecological niches, B. pseudomallei has evolved specialized pathways, including the Type VI secretion systems (T6SSs), that have a role in pathogenesis as well as interbacterial interactions. We examined the expression profile of B. pseudomallei T6SS six gene clusters during infection of U937 macrophage cells. T6SS-5 was robustly transcribed while the other five clusters were not significantly regulated proposing the utility of T6SS-5 as a potential biomarker of exposure to B. pseudomallei. Transcription of T6SS regulators VirAG and BprB was also not significant during infection when compared to bacteria grown in culture. Guided by these findings, three highly expressed T6SS genes, tssJ-4, hcp1 and tssE-5, were expressed as recombinant proteins and screened against melioidosis patient sera by western analysis and ELISA. Only Hcp1 was reactive by both types of analysis. The recombinant Hcp1 protein was further evaluated against a cohort of melioidosis patients (n = 32) and non-melioidosis individuals (n = 20) sera and the data clearly indicates a higher sensitivity (93.7%) and specificity (100%) for Hcp1 compared to bacterial lysate. The detection of anti-Hcp1 antibodies in patients' sera indicating the presence of B. pseudomallei highlights the potential of Hcp1 to be further developed as a serodiagnostic marker for melioidosis.

Matched MeSH terms: Melioidosis/diagnosis*
Fulltext Cutaneous melioidosis in a healthy Danish man after travelling to South-East Asia

Bodilsen J, Langgaard H, Nielsen HL

BMJ Case Rep, 2015 Jan 16;2015.
PMID: 25596295 DOI: 10.1136/bcr-2014-207340

A healthy Danish man presented with infected prepatellar bursitis 8 months after being involved in a car accident in Malaysia resulting in exposure of a laceration of his knee to stagnant water. Tissue samples grew Burkholderia pseudomallei and diagnostic work up revealed no secondary foci. The patient was successfully treated with surgical debridement and 3 months of oral trimethoprim-sulfamethoxazole. At 6 months follow-up the patient was without relapse.

Matched MeSH terms: Melioidosis/diagnosis*
Intracoronary blood sampling with a microcatheter for the diagnosis of giant infective coronary aneurysm: Melioidosis of coronary artery mycotic aneurysm

Yew KL, Choy CN, Kam JY, Kang Z

Int J Cardiol, 2015;187:530-1.
PMID: 25863294 DOI: 10.1016/j.ijcard.2015.04.013
Matched MeSH terms: Melioidosis/diagnosis
In situ hybridization to detect and identify Burkholderia pseudomallei in human melioidosis

Eu LC, Ong KC, Hiu J, Vadivelu J, Nathan S, Wong KT

Mod Pathol, 2014 May;27(5):657-64.
PMID: 24186135 DOI: 10.1038/modpathol.2013.184

Burkholderia pseudomallei causes a potentially fatal infection called melioidosis. We have developed a nonfluorescent, colorimetric in situ hybridization assay using a specific probe to target 16s rRNA of B. pseudomallei in formalin-fixed, paraffin-embedded infected tissues for diagnostic purposes and to study infectious disease pathology. A 63-base pair DNA probe was synthesized and labeled with digoxigenin by PCR. Probe specificity was confirmed by BLAST analysis and by testing on appropriate microbial controls. The in situ hybridization assay was specifically and consistently positive for B. pseudomallei, showing strongly and crisply stained, single bacillus and bacilli clusters in mainly inflamed tissues in seven human acute melioidosis cases and experimentally infected mouse tissues. Intravascular and extravascular bacilli were detected in both intracellular and extracellular locations in various human organs, including lung, spleen, kidney, liver, bone marrow, and aortic mycotic aneurysm, particularly in the inflamed areas. Intravascular, intracellular bacteria in melioidosis have not been previously reported. Although the identity of infected intravascular leukocytes has to be confirmed, extravascular, intracellular bacilli appear to be found mainly within macrophages and neutrophils. Rarely, large intravascular, extracellular bacillary clusters/emboli could be detected in both human and mouse tissues. B. cepacia and non-Burkholderia pathogens (16 microbial species) all tested negative. Nonpathogenic B. thailandensis showed some cross-hybridization but signals were less intense. This in situ hybridization assay could be usefully adapted for B. pseudomallei identification in other clinical specimens such as pus and sputum.

Matched MeSH terms: Melioidosis/diagnosis*

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