A Review of Melioidosis Cases in the Americas

Latent melioidosis activation presenting with urinary tract infection and bacteremia

We report a rare case of latent melioidosis activation in a patient with a distant travel history to an endemic region. Melioidosis is an infection caused by Burkholderia pseudomallei which is highly endemic in Southeast Asia and northern Australia. The patient exhibited common clinical risk factors, presenting with urinary tract infection and bacteremia. The treatment course was complicated by the adverse effect of trimethoprim/sulfamethoxazole. This case underscores the importance of early detection and appropriate treatment of melioidosis, particularly given its expanding global distribution.

A Rare Case of Melioidosis in the Bronx

Melioidosis is caused by a gram-negative bacillus Burkholderia pseudomallei (B. pseudomallei), which is found in water and soil in endemic areas. There are indicators that B. pseudomallei is increasing in endemic regions and expanding into new locations. It is unclear whether this is because of expanded boundaries or improved detection capabilities. It is even theorized to be endemic in certain parts of the USA. The most common medical risk factor is diabetes mellitus, and it frequently presents as acute pneumonia, and often progresses to bacteremia. It is designated as a tier 1 select biological agent and toxin by the CDC. In this case report, we present a 67-year-old male with multiple comorbidities, who contracted melioidosis while visiting Honduras, as well as the laboratory's response to the occupational exposure.

Locally Acquired Melioidosis Linked to Environment - Mississippi, 2020-2023

Melioidosis, caused by Burkholderia pseudomallei, is a rare but potentially fatal bacterial disease endemic to tropical and subtropical regions worldwide. It is typically acquired through contact with contaminated soil or fresh water. Before this investigation, B. pseudomallei was not known to have been isolated from the environment in the continental United States. Here, we report on three patients living in the same Mississippi Gulf Coast county who presented with melioidosis within a 3-year period. They were infected by the same Western Hemisphere B. pseudomallei strain that was discovered in three environmental samples collected from the property of one of the patients. These findings indicate local acquisition of melioidosis from the environment in the Mississippi Gulf Coast region.

Epetraborole, a leucyl-tRNA synthetase inhibitor, demonstrates murine efficacy, enhancing the in vivo activity of ceftazidime against Burkholderia pseudomallei, the causative agent of melioidosis

Burkholderia pseudomallei is the causative agent of melioidosis, which is increasingly being reported worldwide. Mortality rates as high as 40% have been reported based on clinical patient outcomes in the endemic areas of Australia and Thailand. Novel therapies are needed to reduce treatment duration and adverse effects and improve treatment outcomes. Epetraborole, a novel antibiotic, targets leucyl-tRNA synthetase (LeuRS), an essential enzyme that catalyzes the attachment of leucine to transfer RNA. Epetraborole was evaluated for in vitro activity and efficacy in a murine model to assess clinical relevance against Burkholderia pseudomallei infections for possible treatment of melioidosis. Epetraborole was tested against 13 clinically derived and three reference B. pseudomallei strains that have a broad spectrum of susceptibilities to the standard-of-care (SoC) drugs for melioidosis, which showed that epetraborole exhibited minimal inhibitory concentrations of 0.25-4 μg/mL. Ex vivo studies using THP-1 macrophages confirmed the potency of epetraborole and demonstrated synergy between epetraborole and ceftazidime. In the acute pulmonary murine infection model of melioidosis, epetraborole demonstrated equivalent efficacy when delivered orally or subcutaneously, which compared well with the standard-of-care drug ceftazidime. In addition, adding epetraborole to ceftazidime significantly improved antimicrobial activity in this animal model. This work warrants further exploration of epetraborole as a candidate for treating melioidosis and substantiates LeuRS as a clinically relevant drug target in B. pseudomallei.

Effect of fluoxetine on planktonic and biofilm growth and the antimicrobial susceptibility of Burkholderia pseudomallei

Aim: This study evaluated the effect of fluoxetine (FLU) on planktonic and biofilm growth and the antimicrobial susceptibility of Burkholderia pseudomallei. Materials & methods: The minimum inhibitory concentrations (MICs) for FLU were determined by broth microdilution. Its effect on growing and mature biofilms and its interaction with antibacterial drugs were evaluated by assessing biofilm metabolic activity, biomass and structure through confocal microscopy. Results: The FLU MIC range was 19.53-312.5 μg/ml. FLU eradicated growing and mature biofilms of B. pseudomallei at 19.53-312.5 μg/ml and 1250-2500 μg/ml, respectively, with no structural alterations and enhanced the antibiofilm activity of antimicrobial drugs. Conclusion: These results bring perspectives for the use of FLU in the treatment of melioidosis, requiring further studies to evaluate its applicability.

Rational design of an acidic erythritol (ACER) medium for the enhanced isolation of the environmental pathogen Burkholderia pseudomallei from soil samples

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 erythritol-based 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.

In vitro effect of the iron chelator deferiprone on the antimicrobial susceptibility and biofilms of Burkholderia pseudomallei

This study evaluated the effect of the iron chelator deferiprone (DFP) on antimicrobial susceptibility and biofilm formation and maintenance by Burkholderia pseudomallei. Planktonic susceptibility to DFP alone and in combination with antibiotics was evaluated by broth microdilution and biofilm metabolic activity was determined with resazurin. DFP minimum inhibitory concentration (MIC) range was 4-64 µg/mL and in combination reduced the MIC for amoxicillin/clavulanate and meropenem. DFP reduced the biomass of biofilms by 21 and 12% at MIC and MIC/2, respectively. As for mature biofilms, DFP reduced the biomass by 47%, 59%, 52% and 30% at 512, 256, 128 and 64 µg/mL, respectively, but did not affect B. pseudomallei biofilm viability nor increased biofilm susceptibility to amoxicillin/clavulanate, meropenem and doxycycline. DFP inhibits planktonic growth and potentiates the effect of β-lactams against B. pseudomallei in the planktonic state and reduces biofilm formation and the biomass of B. pseudomallei biofilms.

Melioidosis in Cynomolgus Macaques ( Macaca Fascicularis ) Imported to the United States from Cambodia

Melioidosis, a potentially fatal infectious disease of humans and animals, including nonhuman primates (NHPs), is caused by the high-consequence pathogen Burkholderia pseudomallei. This environmental bacterium is found in the soil and water of tropical regions, such as Southeast Asia, where melioidosis is endemic. The global movement of humans and animals can introduce B. pseudomallei into nonendemic regions of the United States, where environmental conditions could allow establishment of the organism. Approximately 60% of NHPs imported into the United States originate in countries considered endemic for melioidosis. To prevent the introduction of infectious agents to the United States, the Centers for Disease Control and Prevention (CDC) requires newly imported NHPs to be quarantined for at least 31 d, during which time their health is closely monitored. Most diseases of public health concern that are transmissible from imported NHPs have relatively short incubation periods that fall within the 31-d quarantine period. However, animals infected with B. pseudomallei may appear healthy for months to years before showing signs of illness, during which time they can shed the organism into the environment. Melioidosis presents diagnostic challenges because it causes nonspecific clinical signs, serologic screening can produce unreliable results, and culture isolates are often misidentified on rapid commercial testing systems. Here, we present a case of melioidosis in a cynomolgus macaque (Macaca fascicularis) that developed a subcutaneous abscess after importation from Cambodia to the United States. The bacterial isolate from the abscess was initially misidentified on a commercial test. This case emphasizes the possibility of melioidosis in NHPs imported from endemic countries and its associated diagnostic challenges. If melioidosis is suspected, diagnostic samples and culture isolates should be submitted to a laboratory in the CDC Laboratory Response Network for conclusive identification and characterization of the pathogen.

Low risk of acquiring melioidosis from the environment in the continental United States

Melioidosis is an underreported human disease of tropical and sub-tropical regions caused by the saprophyte Burkholderia pseudomallei. Although most global melioidosis cases are reported from tropical regions in Southeast Asia and northern Australia, there are multiple occurrences from sub-tropical regions, including the United States (U.S.). Most melioidosis cases reported from the continental U.S. are the result of acquiring the disease during travel to endemic regions or from contaminated imported materials. Only two human melioidosis cases from the continental U.S. have likely acquired B. pseudomallei directly from local environments and these cases lived only ~7 km from each other in rural Texas. In this study, we assessed the risk of acquiring melioidosis from the environment within the continental U.S. by surveying for B. pseudomallei in the environment in Texas where these two human melioidosis cases likely acquired their infections. We sampled the environment near the homes of the two cases and at additional sampling locations in surrounding counties in Texas that were selected based on ecological niche modeling. B. pseudomallei was not detected at the residences of these two cases or in the surrounding region. These negative data are important to demonstrate that B. pseudomallei is rare in the environment in the U.S. even at locations where locally acquired human cases likely have occurred, documenting the low risk of acquiring B. pseudomallei infection from the environment in the continental U.S.

Drivers of melioidosis endemicity: epidemiological transition, zoonosis, and climate change

PURPOSE OF REVIEW

Melioidosis, caused by the soil-dwelling bacterium Burkholderia pseudomallei, is a tropical infection associated with high morbidity and mortality. This review summarizes current insights into melioidosis' endemicity, focusing on epidemiological transitions, zoonosis, and climate change.

RECENT FINDINGS

Estimates of the global burden of melioidosis affirm the significance of hot-spots in Australia and Thailand. However, it also highlights the paucity of systematic data from South Asia, The Americas, and Africa. Globally, the growing incidence of diabetes, chronic renal and (alcoholic) liver diseases further increase the susceptibility of individuals to B. pseudomallei infection. Recent outbreaks in nonendemic regions have further exposed the hazard from the trade of animals and products as potential reservoirs for B. pseudomallei. Lastly, global warming will increase precipitation, severe weather events, soil salinity and anthrosol, all associated with the occurrence of B. pseudomallei.

SUMMARY

Epidemiological transitions, zoonotic hazards, and climate change are all contributing to the emergence of novel melioidosis-endemic areas. The adoption of the One Health approach involving multidisciplinary collaboration is important in unraveling the real incidence of B. pseudomallei, as well as reducing the spread and associated mortality.

In silico analyses of penicillin binding proteins in Burkholderia pseudomallei uncovers SNPs with utility for phylogeography, species differentiation, and sequence typing

Burkholderia pseudomallei causes melioidosis. Sequence typing this pathogen can reveal geographical origin and uncover epidemiological associations. Here, we describe B. pseudomallei genes encoding putative penicillin binding proteins (PBPs) and investigate their utility for determining phylogeography and differentiating closely related species. We performed in silico analysis to characterize 10 PBP homologs in B. pseudomallei 1026b. As PBP active site mutations can confer β-lactam resistance in Gram-negative bacteria, PBP sequences in two resistant B. pseudomallei strains were examined for similar alterations. Sequence alignments revealed single amino acid polymorphisms (SAAPs) unique to the multidrug resistant strain Bp1651 in the transpeptidase domains of two PBPs, but not directly within the active sites. Using BLASTn analyses of complete assembled genomes in the NCBI database, we determined genes encoding PBPs were conserved among B. pseudomallei (n = 101) and Burkholderia mallei (n = 26) strains. Within these genes, single nucleotide polymorphisms (SNPs) useful for predicting geographic origin of B. pseudomallei were uncovered. SNPs unique to B. mallei were also identified. Based on 11 SNPs identified in two genes encoding predicted PBP-3s, a dual-locus sequence typing (DLST) scheme was developed. The robustness of this typing scheme was assessed using 1,523 RefSeq genomes from B. pseudomallei (n = 1,442) and B. mallei (n = 81) strains, resulting in 32 sequence types (STs). Compared to multi-locus sequence typing (MLST), the DLST scheme demonstrated less resolution to support the continental separation of Australian B. pseudomallei strains. However, several STs were unique to strains originating from a specific country or region. The phylogeography of Western Hemisphere B. pseudomallei strains was more highly resolved by DLST compared to internal transcribed spacer (ITS) typing, and all B. mallei strains formed a single ST. Conserved genes encoding PBPs in B. pseudomallei are useful for strain typing, can enhance predictions of geographic origin, and differentiate strains of closely related Burkholderia species.

Burkholderia pseudomallei causes the life-threatening disease melioidosis and is considered a biological threat and select agent by the United States government. This soil-dwelling bacterium is commonly found in regions of southeast Asia and northern Australia, but it is also detected in other tropical and sub-tropical areas around the world. With a predicted global burden of 165,000 annual cases and mortality rate that can exceed 40% without prompt and appropriate antibiotic treatment, understanding the epidemiology of melioidosis and mechanisms of antibiotic resistance in B. pseudomallei can benefit public health and safety. Recently, we identified ten conserved genes encoding putative penicillin binding proteins (PBPs) in B. pseudomallei. Here, we examined B. pseudomallei PBP sequences for amino acid mutations that may contribute to β-lactam resistance. We also uncovered nucleotide mutations with utility to predict the geographical origin of B. pseudomallei strains and to differentiate closely related Burkholderia species. Based on 11 informative single nucleotide polymorphisms in two genes each encoding a PBP-3, we developed a simple, targeted dual-locus typing approach.

Multistate Outbreak of Melioidosis Associated with Imported Aromatherapy Spray

Melioidosis, caused by the bacterium Burkholderia pseudomallei, is an uncommon infection that is typically associated with exposure to soil and water in tropical and subtropical environments. It is rarely diagnosed in the continental United States. Patients with melioidosis in the United States commonly report travel to regions where melioidosis is endemic. We report a cluster of four non-travel-associated cases of melioidosis in Georgia, Kansas, Minnesota, and Texas. These cases were caused by the same strain of B. pseudomallei that was linked to an aromatherapy spray product imported from a melioidosis-endemic area.

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.

Human Melioidosis Caused by Novel Transmission of Burkholderia pseudomallei from Freshwater Home Aquarium, United States1

Nearly all cases of melioidosis in the continental United States are related to international travel to areas to which Burkholderia pseudomallei, the bacterium that causes melioidosis, is endemic. We report the diagnosis and clinical course of melioidosis in a patient from the United States who had no international travel history and the public health investigation to determine the source of exposure. We tested environmental samples collected from the patient’s home for B. pseudomallei by PCR and culture. Whole-genome sequencing was conducted on PCR-positive environmental samples, and results were compared with sequences from the patient’s clinical specimen. Three PCR-positive environmental samples, all collected from a freshwater home aquarium that had contained imported tropical fish, were a genetic match to the clinical isolate from the patient. This finding suggests a novel route of exposure and a potential for importation of B. pseudomallei, a select agent, into the United States from disease-endemic areas.

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.

Melioidosis in a Resident of Texas with No Recent Travel History, United States

To our knowledge, environmental isolation of Burkholderia pseudomallei, the causative agent of melioidosis, from the continental United States has not been reported. We report a case of melioidosis in a Texas resident. Genomic analysis indicated that the isolate groups with B. pseudomallei isolates from patients in the same region, suggesting possible endemicity to this region.

Genomic Diversity of Burkholderia pseudomallei Isolates, Colombia

We report an analysis of the genomic diversity of isolates of Burkholderia pseudomallei, the cause of melioidosis, recovered in Colombia from routine surveillance during 2016–2017. B. pseudomallei appears genetically diverse, suggesting it is well established and has spread across the region.

Three New Cases of Melioidosis, Guadeloupe, French West Indies

Melioidosis has been detected in the Caribbean, and an increasing number of cases has been reported in the past few decades, but only 2 cases were reported in Guadeloupe during the past 20 years. We describe 3 more cases that occurred during 2016–2017 and examine arguments for increasing endemicity.

Geographic Distribution and Incidence of Melioidosis, Panama1

Melioidosis is an infection caused by Burkholderia pseudomallei. Most cases occur in Southeast Asia and northern Australia; <100 cases have been reported in the Americas. We conducted a retrospective study and identified 12 melioidosis cases in Panama during 2007–2017, suggesting possible endemicity and increased need for surveillance.

Description of two fatal cases of melioidosis in Mexican children with acute pneumonia: case report

BACKGROUND

Melioidosis is an infectious disease caused by Burkholderia pseudomallei. In Mexico, the disease is rarely diagnosed in humans and there is no evidence of simultaneous environmental isolation of the pathogen. Here, we describe clinical profiles of fatal cases of melioidosis in two children, in a region without history of that disease.

CASE PRESENTATION

About 48 h before onset of symptoms, patients swam in a natural body of water, and thereafter they rapidly developed fatal septicemic illness. Upon necropsy, samples from liver, spleen, lung, cerebrospinal fluid, and bronchial aspirate tissues contained Burkholderia pseudomallei. Environmental samples collected from the locations where the children swam also contained B. pseudomallei. All the clinical and environmental strains showed the same BOX-PCR pattern, suggesting that infection originated from the area where the patients were swimming.

CONCLUSIONS

The identification of B. pseudomallei confirmed that melioidosis disease exists in Sonora, Mexico. The presence of B. pseudomallei in the environment may suggest endemicity of the pathogen in the region. This study highlights the importance of strengthening laboratory capacity to prevent and control future melioidosis cases.

Genomic Diversity of Burkholderia pseudomallei in Ceara, Brazil

B. pseudomallei causes significant morbidity and mortality, but its geographic prevalence and genetic diversity are not well characterized, especially in the Western Hemisphere. A better understanding of the genetic relationships among clinical and environmental isolates will improve knowledge of the population structure of this bacterium as well as the ability to conduct epidemiological investigations of cases of melioidosis.

Burkholderia pseudomallei is a Gram-negative bacterium that causes the sapronotic disease melioidosis. An outbreak in 2003 in the state of Ceara, Brazil, resulted in subsequent surveillance and environmental sampling which led to the recognition of B. pseudomallei as an endemic pathogen in that area. From 2003 to 2015, 24 clinical and 12 environmental isolates were collected across Ceara along with one from the state of Alagoas. Using next-generation sequencing, multilocus sequence typing, and single nucleotide polymorphism analysis, we characterized the genomic diversity of this collection to better understand the population structure of B. pseudomallei associated with Ceara. We found that the isolates in this collection form a distinct subclade compared to other examples from the Western Hemisphere. Substantial genetic diversity among the clinical and environmental isolates was observed, with 14 sequence types (STs) identified among the 37 isolates. Of the 31,594 core single-nucleotide polymorphisms (SNPs) identified, a high proportion (59%) were due to recombination. Because recombination events do not follow a molecular clock, the observation of high occurrence underscores the importance of identifying and removing recombination SNPs prior to evolutionary reconstructions and inferences in public health responses to B. pseudomallei outbreaks. Our results suggest long-term B. pseudomallei prevalence in this recently recognized region of melioidosis endemicity.

IMPORTANCEB. pseudomallei causes significant morbidity and mortality, but its geographic prevalence and genetic diversity are not well characterized, especially in the Western Hemisphere. A better understanding of the genetic relationships among clinical and environmental isolates will improve knowledge of the population structure of this bacterium as well as the ability to conduct epidemiological investigations of cases of melioidosis.

Case Report: Gestational Melioidosis through Perinatal Transmission

Burkholderia pseudomallei is an emerging pathogen in the Americas. Cases of mother-to-child transmission of B. pseudomallei are rare and probably occur by placental or perinatal infection. We report the first case of native gestational and neonatal melioidosis in the Western hemisphere. The isolated strains in the mother and newborn were confirmed by whole-genome sequencing and identified as a novel sequence type ST1748. The comparison of both genomes revealed a nucleotide similarity of 100%. Melioidosis should be considered within the differential diagnosis of febrile illness or pneumonia in pregnant women and newborns from endemic areas of the Americas.

Burkholderia pseudomallei pathogenesis and survival in different niches

Burkholderia pseudomallei (Bp) is the causative agent of melioidosis, a disease of the tropics with high clinical mortality rates. To date, no vaccines are approved for melioidosis and current treatment relies on antibiotics. Conversely, common misdiagnosis and high pathogenicity of Bp hamper efforts to fight melioidosis. This bacterium can be isolated from a wide range of niches such as waterlogged fields, stagnant water bodies, salt water bodies and from human and animal clinical specimens. Although extensive studies have been undertaken to elucidate pathogenesis mechanisms of Bp, little is known about how a harmless soil bacterium adapts to different environmental conditions, in particular, the shift to a human host to become a highly virulent pathogen. The bacterium has a large genome encoding an armory of factors that assist the pathogen in surviving under stressful conditions and assuming its role as a deadly intracellular pathogen. This review presents an overview of what is currently known about how the pathogen adapts to different environments. With in-depth understanding of Bp adaptation and survival, more effective therapies for melioidosis can be developed by targeting related genes or proteins that play a major role in the bacteria's survival.

Human Melioidosis

The causative agent of melioidosis, Burkholderia pseudomallei, a tier 1 select agent, is endemic in Southeast Asia and northern Australia, with increased incidence associated with high levels of rainfall. Increasing reports of this condition have occurred worldwide, with estimates of up to 165,000 cases and 89,000 deaths per year. The ecological niche of the organism has yet to be clearly defined, although the organism is associated with soil and water. The culture of appropriate clinical material remains the mainstay of laboratory diagnosis. Identification is best done by phenotypic methods, although mass spectrometric methods have been described. Serology has a limited diagnostic role. Direct molecular and antigen detection methods have limited availability and sensitivity. Clinical presentations of melioidosis range from acute bacteremic pneumonia to disseminated visceral abscesses and localized infections. Transmission is by direct inoculation, inhalation, or ingestion. Risk factors for melioidosis include male sex, diabetes mellitus, alcohol abuse, and immunosuppression. The organism is well adapted to intracellular survival, with numerous virulence mechanisms. Immunity likely requires innate and adaptive responses. The principles of management of this condition are drainage and debridement of infected material and appropriate antimicrobial therapy. Global mortality rates vary between 9% and 70%. Research into vaccine development is ongoing.

Case Series Study of Melioidosis, Colombia

We report 7 cases of melioidosis in Colombia and comparision of 4 commercial systems for identifying Burkholderia pseudomallei. Phoenix systems were not a definitive method for identifying B. pseudomallei. For accurate identification, we recommend including this bacterium in the library databases of matrix-assisted laser desorption/ionization mass spectrometry systems in Latin America.

Study of Iron Piperazine-Based Chelators as Potential Siderophore Mimetics

Gram-negative bacteria’s resistance such as Pseudomonas aeruginosa and the Burkholderia group to conventional antibiotics leads to therapeutic failure. Use of siderophores as Trojan horses to internalize antibacterial agents or toxic metals within bacteria is a promising strategy to overcome resistance phenomenon. To combat the Pseudomonas sp, we have synthesized and studied two piperazine-based siderophore mimetics carrying either catecholate moieties (1) or hydroxypyridinone groups (2) as iron chelators. These siderophore-like molecules were prepared in no more than four steps with good global yields. The physicochemical study has highlighted a strong iron affinity since their pFe values were higher than 20. 1 possesses even a pFe value superior than those of pyoverdine, the P. aeruginosa endogenous siderophore, suggesting its potential ability to compete with it. At physiological pH, 1 forms mainly a 2:3 complex with iron, whereas two species are observed for 2. Unfortunately, the corresponding Ga(III)-1 and 2 complexes showed no antibacterial activity against P. aeruginosa DSM 1117 strain. The evaluation of their siderophore-like activity showed that 1 and 2 could be internalized by the bacteria.

Melioidosis after Hurricanes Irma and Maria, St. Thomas/St. John District, US Virgin Islands, October 2017

We report 2 cases of melioidosis in women with diabetes admitted to an emergency department in the US Virgin Islands during October 2017. These cases emerged after Hurricanes Irma and Maria and did not have a definitively identified source. Poor outcomes were observed when septicemia and pulmonary involvement were present.

Melioidosis in Colombia, description of a clinical case and epidemiological considerations

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.

A review of melioidosis cases imported into Europe

Melioidosis is a tropical bacterial infection, rarely encountered, and poorly known by clinicians. In non-endemic areas, a misdiagnosis can lead to a fatal outcome. This study aims to identify the main characteristics of imported and diagnosed melioidosis cases in Europe to increase clinician's awareness of this diagnosis. A literature review of imported and diagnosed human melioidosis cases in Europe was performed. PubMed and Web of Science search engines were used for retrieving articles from 2000 to November 2018. Seventy-seven cases of imported melioidosis into Europe described in the literature were identified. More than half of the cases were acquired in Thailand (53%) by men (73%). Patients were usually exposed to Burkholderia pseudomallei during a holiday stay (58%) of less than 1 month (23%) and were hospitalized during the month following their return to Europe (58%). Among travelers, melioidosis is less often associated with risk factor (16%), diabetes being the most frequently comorbidity related (19%). The clinical presentation was multifaceted, pneumonia being the most common symptom (52%), followed by cardiovascular form (45%) and skin and soft tissues damages (35%). The diagnosis was obtained by culture (92%), often supplemented by morphological, biochemical, and molecular identification (23%). Misdiagnoses were common (21%). Over half of the patients received a complete and adapted treatment (56%). Mortality is lower for returning traveler (6%). Imported melioidosis cases into Europe have their own characteristics. This possibility should be considered in patients with pneumonia, fever, and/or abscess returning from endemic areas even years after.

Melioidosis, an emerging infectious disease in the Midwest Brazil: A case report

RATIONALE

Melioidosis is an emerging infectious disease in Brazil and caused by Burkholderia pseudomallei, with high morbidity and mortality rates. A total of 28 melioidosis cases were reported in Brazil until 2015. The majority of melioidosis cases were reported in the Northwest region of Brazil and such cases were not previously detected in the Midwest region of Brazil.

PATIENT CONCERNS

A 42-year-old man was admitted with a non-productive cough, dyspnea, myalgia, diffuse abdominal pain. Pulmonary auscultation revealed a vesicular murmur, snoring sounds, and the presence of basal crackling rales in the left hemithorax. The patient evolved with several respiratory failures and he was diagnosed as the first case of community-acquired pneumonia with sepsis caused by B pseudomallei in Mato Grosso do Sul, Midwest state of Brazil.

DIAGNOSIS

The cell isolates were subjected to 16S rRNA gene sequencing to confirm the bacterial species.

INTERVENTIONS

Administration of trimethoprim/sulfamethoxazole and meropenem stabilized the clinical condition of the patient. Subsequently upon discharge, the patient was also treated with trimethoprim/sulfametothoxazole for a year.

OUTCOME

We reported the first case of community-acquired pneumonia with sepsis caused by B pseudomallei in Mato Grosso do Sul, Midwest state of Brazil and the patient survived.

LESSONS

The emergence of melioidosis in the Midwest region is being neglected and underestimated and melioidosis must be considered of the differential diagnosis in community infections.

Caprine humoral response to Burkholderia pseudomallei antigens during acute melioidosis from aerosol exposure

Burkholderia pseudomallei causes melioidosis, a common source of pneumonia and sepsis in Southeast Asia and Northern Australia that results in high mortality rates. A caprine melioidosis model of aerosol infection that leads to a systemic infection has the potential to characterize the humoral immune response. This could help identify immunogenic proteins for new diagnostics and vaccine candidates. Outbred goats may more accurately mimic human infection, in contrast to the inbred mouse models used to date. B. pseudomallei infection was delivered as an intratracheal aerosol. Antigenic protein profiling was generated from the infecting strain MSHR511. Humoral immune responses were analyzed by ELISA and western blot, and the antigenic proteins were identified by mass spectrometry. Throughout the course of the infection the assay results demonstrated a much greater humoral response with IgG antibodies, in both breadth and quantity, compared to IgM antibodies. Pre-infection sera showed multiple immunogenic proteins already reactive for IgG (7-20) and IgM (0-12) in most of the goats despite no previous exposure to B. pseudomallei. After infection, the number of IgG reactive proteins showed a marked increase as the disease progressed. Early stage infection (day 7) showed immune reaction to chaperone proteins (GroEL, EF-Tu, and DnaK). These three proteins were detected in all serum samples after infection, with GroEL immunogenically dominant. Seven common reactive antigens were selected for further analysis using ELISA. The heat shock protein GroEL1 elicited the strongest goat antibody immune response compared to the other six antigens. Most of the six antigens showed the peak IgM reactivity at day 14, whereas the IgG reactivity increased further as the disease progressed. An overall MSHR511 proteomic comparison between the goat model and human sera showed that many immune reactive proteins are common between humans and goats with melioidosis.

MELIOIDOSIS AND GLANDERS: CURRENT STATE AND ACTUAL ISSUES OF EPIDEMIOLOGICAL SURVEILLANCE

Burkholderia pseudomallei and Burkholderia mallei are etiologic agents of glanders and melioidosis, the particularly dangerous infections of animals and humans, and are attributed to potential agents of bioterrorism. The manifestation of diseases ranges from acute septicemia to chronic infection, any organs and tissues are affected, andtreatment requires long intravenous and oral antibiotic courses. The endemic zone of glanders and melioidosis covers spacious regions in the world, and the number of imported cases to temperate regions is constantly increasing. For the Russian Federation, glanders and melioidosis are «forgotten» and «unknown» infections, and this review presents current data on their distribution in the world, epidemiological aspects, and laboratory diagnosis features.

Melioidosis is in the Americas: A Call to Action for Diagnosing and Treating the Disease

Melioidosis, a disease caused by the pathogen Burkholderia pseudomallei, is a significant underreported endemic disease found in tropical countries worldwide. Recent studies have demonstrated that human melioidosis cases have been increasingly recognized in the Americas. Therefore, the first Scientific Reunion of Melioidosis in the Americas was organized in Colombia, with the participation of health authorities of 11 Latin American countries and the United States. This report summarizes the topics reviewed during the meeting, including how to identify human infections and properly diagnose them, with the goal of increasing recognition of the disease in the Americas.

Melioidosis in South America

Melioidosis is an emerging disease in the Americas. This paper reviews confirmed cases, the presence of Burkholderia pseudomallei and the organization of national surveillance policies for melioidosis in South America. Confirmed cases in humans have been reported from Ecuador, Venezuela, Colombia, Brazil, and Peru. The bacterium has been isolated from the environment in Brazil and Peru. The state of Ceará, northeastern region of Brazil, is the only place where specific public strategies and policies for melioidosis have been developed. We also discuss the urgent need for health authorities in South America to pay greater attention to this disease, which has the potential to have a high impact on public health, and the importance of developing coordinated strategies amongst countries in this region.

A case report: Splenic abscess caused by Burkholderia pseudomallei

RATIONALE

Melioidosis is an emerging infectious disease caused by Burkholderia pseudomallei. To our knowledge, there have been very few cases of splenic abscesses due to melioidosis in Hainan, China.

PATIENT CONCERNS

The patient was a 55-year-old male farmer, who was admitted in our hospital with persistent left epigastric dull pain accompanied by chills and febrile. One month before, the patient presented with persistent abdominal pain. After received anti-infection therapy, the subjective symptoms eased slightly, but recently he suffered from intermittent abdominal pain again.

DIAGNOSES

Bacteria isolated from splenic pus were identified as B. pseudomallei by the Phoenix-100 system and indirect immunofluorescence.

INTERVENTIONS

The patient was treated by surgical excision and anti-infection therapy.

OUTCOMES

The patient was then treated with intravenous ceftazidime and oral trimethoprim-sulfamethoxazole for 2 weeks and his clinical symptoms improved.

LESSONS

In endemic areas, B. pseudomallei should be considered as a causative organism of splenic abscess in patients with established risk factors. The isolation of B. pseudomallei from abscess sites is crucial to improve clinical outcomes by appropriate antimicrobial therapy coupled with surgical drainage.

Phylogeography of Burkholderia pseudomallei Isolates, Western Hemisphere

The bacterium Burkholderia pseudomallei causes melioidosis, which is mainly associated with tropical areas. We analyzed single-nucleotide polymorphisms (SNPs) among genome sequences from isolates of B. pseudomallei that originated in the Western Hemisphere by comparing them with genome sequences of isolates that originated in the Eastern Hemisphere. Analysis indicated that isolates from the Western Hemisphere form a distinct clade, which supports the hypothesis that these isolates were derived from a constricted seeding event from Africa. Subclades have been resolved that are associated with specific regions within the Western Hemisphere and suggest that isolates might be correlated geographically with cases of melioidosis. One isolate associated with a former World War II prisoner of war was believed to represent illness 62 years after exposure in Southeast Asia. However, analysis suggested the isolate originated in Central or South America.

Melioidosis in Mexico, Central America, and the Caribbean

Burkholderia pseudomallei is the causative agent of melioidosis, an endemic disease in tropical areas around the world. Cumulative human cases have demonstrated that melioidosis is prevalent and increasingly recognized in the American continent. Even though the first reports of melioidosis in Mexico, Central America, and the Caribbean Islands date back to the late 1940s, the potential of the disease as a public health concern in the region has not been fully appreciated. Unfortunately, recent studies predicting the global distribution of the disease and the demonstration of melioidosis endemicity in Puerto Rico have not increased recognition of the disease by health professionals in this region. Furthermore, a lack of both diagnostic capacity and awareness of the disease has resulted in a limited number of studies that have attempted to accurately determine its prevalence and geographical distribution. In this review, a summary of reported cases in the countries of this region are presented, as well as recommendations to increase the diagnosis and awareness of the disease as an important public health problem in Mexico, Central America, and the Caribbean islands.

Public health response to an imported case of canine melioidosis

Melioidosis in humans presents variably as fulminant sepsis, pneumonia, skin infection and solid organ abscesses. It is caused by Burkholderia pseudomallei, which in the United States is classified as a select agent, with "potential to pose a severe threat to both human and animal health, to plant health or to animal and plant products" (Federal Select Agent Program, http://www.selectagents.gov/, accessed 22 September 2016). Burkholderia pseudomallei is found in soil and surface water in the tropics, especially South-East Asia and northern Australia, where melioidosis is endemic. Human cases are rare in the United States and are usually associated with travel to endemic areas. Burkholderia pseudomallei can also infect animals. We describe a multijurisdictional public health response to a case of subclinical urinary B. pseudomallei infection in a dog that had been adopted into upstate New York from a shelter in Thailand. Investigation disclosed three human contacts with single, low-risk exposures to the dog's urine at his residence, and 16 human contacts with possible exposure to his urine or culture isolates at a veterinary hospital. Contacts were offered various combinations of symptom/fever monitoring, baseline and repeat B. pseudomallei serologic testing, and antibiotic post-exposure prophylaxis, depending on the nature of their exposure and their personal medical histories. The dog's owner accepted recommendations from public health authorities and veterinary clinicians for humane euthanasia. A number of animal rescue organizations actively facilitate adoptions into the United States of shelter dogs from South-East Asia. This may result in importation of B. pseudomallei into almost any community, with implications for human and animal health.

Clinical, Bacteriologic, and Geographic Stratification of Melioidosis Emerges from the Sri Lankan National Surveillance Program

Melioidosis, a potentially fatal tropical infection, is said to be underdiagnosed in low-income countries. An increase in melioidosis cases in Sri Lanka allowed us to analyze the relationship among clinical outcome, bacteriology, epidemiology, and geography in the first 108 laboratory-confirmed cases of melioidosis from a nationwide surveillance program. The additional 76 cases of laboratory-confirmed melioidosis confirmed further associations between Burkholderia pseudomallei multilocus sequence typing (MLST) and infection phenotype; ST1137/unifocal bacteremic infection (χ² = 3.86, P < 0.05), ST1136/multifocal infection without bacteremia (χ² = 15.8, P < 0.001), and ST1132/unifocal nonbacteremic infection (χ² = 6.34, P = 0.02). ST1137 infections were predominantly seen in the Western Province, whereas ST1132, 1135, and 1136 infections predominated in the Northwestern Province. Early participating centers in the surveillance program had a lower melioidosis-associated mortality than later participants (χ² = 3.99, P < 0.05). The based upon related sequence types (eBURST) algorithm, a MLST clustering method that infers founding genotypes and patterns of descent for related isolates and clonal complexes in an unrooted tree, showed uneven distribution of sequence types (STs). There was spatial clustering of the commonest STs (ST1132, 1136, and 1137) in the Western, Northwestern, and Central provinces. The recent increase in melioidosis in Sri Lanka uncovered by laboratory-enhanced surveillance is likely to be the result of a combination of improved laboratory detection, increased clinician awareness, recruitment of clinical centers, and small outbreaks. Further development of the surveillance program into a national genotyping-supported melioidosis registry will improve melioidosis diagnosis, treatment, and prevention where underdiagnosis and mortality rates remain high.

Clinical and environmental isolates of Burkholderia pseudomallei from Brazil: Genotyping and detection of virulence gene

OBJECTIVE

To evaluate the genetic diversity of clinical and environmental isolates of Burkholderia pseudomallei (B. pseudomallei) recovered in Ceará, Brazil, and screen these isolates for the presence of type three secretion system virulence gene.

METHODS

Nineteen B. pseudomallei isolates (9 from clinical cases and 10 from soils) were analyzed. Random amplified polymorphic DNA was performed with primers OPQ-2, OPQ-4 and OPQ-16 to evaluate the genetic diversity, and type three secretion system gene was detected through polymerase chain reaction.

RESULTS

Random amplified polymorphic DNA showed a genetic relatedness of approximately 50% among the tested B. pseudomallei isolates, which were grouped into two clades, of which the biggest ones comprised 18/19 isolates for primer OPQ-2, and 17/19 isolates for primer OPQ-16. Primer OPQ-4 grouped the isolates into three clades comprising 1/19, 3/19 and 15/19 isolates. Additionally, type three secretion system gene was detected in all tested isolates.

CONCLUSIONS

This is an effort to type B. pseudomallei strains from Ceará, which is important for better understanding this pathogen, contributing for the epidemiological surveillance of melioidosis in this endemic region.

Emerging Infections and Pertinent Infections Related to Travel for Patients with Primary Immunodeficiencies

In today's global economy and affordable vacation travel, it is increasingly important that visitors to another country and their physician be familiar with emerging infections, infections unique to a specific geographic region, and risks related to the process of travel. This is never more important than for patients with primary immunodeficiency disorders (PIDD). A recent review addressing common causes of fever in travelers provides important information for the general population Thwaites and Day (N Engl J Med 376:548-560, 2017). This review covers critical infectious and management concerns specifically related to travel for patients with PIDD. This review will discuss the context of the changing landscape of infections, highlight specific infections of concern, and profile distinct infection phenotypes in patients who are immune compromised. The organization of this review will address the environment driving emerging infections and several concerns unique to patients with PIDD. The first section addresses general considerations, the second section profiles specific infections organized according to mechanism of transmission, and the third section focuses on unique phenotypes and unique susceptibilities in patients with PIDDs. This review does not address most parasitic diseases. Reference tables provide easily accessible information on a broader range of infections than is described in the text.

PKC-η-MARCKS Signaling Promotes Intracellular Survival of Unopsonized Burkholderia thailandensis

Pathogenic Burkholderia rely on host factors for efficient intracellular replication and are highly refractory to antibiotic treatment. To identify host genes that are required by Burkholderia spp. during infection, we performed a RNA interference (RNAi) screen of the human kinome and identified 35 host kinases that facilitated Burkholderia thailandensis intracellular survival in human monocytic THP-1 cells. We validated a selection of host kinases using imaging flow cytometry to assess efficiency of B. thailandensis survival in the host upon siRNA-mediated knockdown. We focused on the role of the novel protein kinase C isoform, PKC-η, in Burkholderia infection and characterized PKC-η/MARCKS signaling as a key event that promotes the survival of unopsonized B. thailandensis CDC2721121 within host cells. While infection of lung epithelial cells with unopsonized Gram-negative bacteria stimulated phosphorylation of Ser175/160 in the MARCKS effector domain, siRNA-mediated knockdown of PKC-η expression reduced the levels of phosphorylated MARCKS by >3-fold in response to infection with Bt CDC2721121. We compared the effect of the conventional PKC-α and novel PKC-η isoforms on the growth of B. thailandensis CDC2721121 within monocytic THP-1 cells and found that ≥75% knock-down of PRKCH transcript levels reduced intracellular bacterial load 100% more efficiently when compared to growth in cells siRNA-depleted of the classical PKC-α, suggesting that the PKC-η isoform can specifically mediate Burkholderia intracellular survival. Based on imaging studies of intracellular B. thailandensis, we found that PKC-η function stimulates phagocytic pathways that promote B. thailandensis escape into the cytoplasm leading to activation of autophagosome flux. Identification of host kinases that are targeted by Burkholderia during infection provides valuable molecular insights in understanding Burkholderia pathogenesis, and ultimately, in designing effective host-targeted therapies against infectious disease caused by intracellular pathogens.

Comparing in vitro and in vivo virulence phenotypes of Burkholderia pseudomallei type G strains

Burkholderia pseudomallei (Bpm) is a saprophytic rod-shaped gram-negative bacterium and the causative agent of melioidosis. This disease has previously been described as endemic in areas such as northern Australia and Southeast Asia, but, more recently, a better understanding of the epidemiology of melioidosis indicated that the disease is distributed worldwide, including regions of the Americas and Africa. A 16S-23S rDNA internal transcribed spacer (ITS) typing system has been developed for Bpm and has revealed that ITS types C, E, and hybrid CE are mainly associated with Australia and Southeast Asia while type G strains are more associated with cases of melioidosis in the Western Hemisphere. The purpose of the current study was to determine the in vitro and in vivo virulence profiles of the understudied Bpm type G strains Ca2009, Ca2013a, Mx2013, and 724644 and compared such phenotypes to the commonly studied Bpm type C strain K96243. We evaluated virulence by measuring invasion/uptake and survival of these Bpm strains in murine respiratory epithelial LA-4 cells and alveolar macrophage MH-S cells using different multiplicity of infections (MOIs of 1 and 10). We also calculated the lethal dose 50 values (LD₅₀) in BALB/c mice that were inoculated intranasally with either Ca2009, Ca2013a, or Mx2013. Overall, the virulence and lethality phenotypes of Bpm type G strains were similar to the Bpm type C strain K96243. Additional comparative analyses between the Bpm ITS types may lead to a better understanding of the contribution of the ITS type to the epidemiology and ecology of Bpm strains.

Emerging infectious diseases with cutaneous manifestations: Viral and bacterial infections

Given increased international travel, immigration, and climate change, bacterial and viral infections that were once unrecognized or uncommon are being seen more frequently in the Western Hemisphere. A delay in diagnosis and treatment of these diseases can lead to significant patient morbidity and mortality. However, the diagnosis and management of these infections is fraught with a lack of consistency because there is a dearth of dermatology literature on the cutaneous manifestations of these infections. We review the epidemiology, cutaneous manifestations, diagnosis, and management of these emerging bacterial and viral diseases.

Neuromelioidosis: a series of seven cases in Hainan province, China

Melioidosis, which is caused by Burkholderia pseudomallei, is predominately a disease of tropical climates and is especially widespread in south-east Asia and northern Australia. Melioidosis affecting the central nervous system has a low incidence but a high mortality. We present seven cases of neuromelioidosis and analyze the disease characteristics and imaging features. Typical clinical features of this disease included high fever and headache. Five patients had an irregular fever with a temperature ≥ 39℃. Peripheral blood leukocytes and the neutrophil ratio were raised in all patients. On computed tomography and magnetic resonance imaging the disease mainly manifested as intracerebral single or multiple nodules, as well as ring and flake-like enhancements with rapid lesion progression. This study demonstrated the importance of imaging examination in the clinical evaluation and diagnosis of neuromelioidosis.