Emergence of Burkholderia pseudomallei Sequence Type 562, Northern Australia

Since 2005, the range of Burkholderia pseudomallei sequence type 562 (ST562) has expanded in northern Australia. During 2005–2019, ST562 caused melioidosis in 61 humans and 3 animals. Cases initially occurred in suburbs surrounding a creek before spreading across urban Darwin, Australia and a nearby island community. In urban Darwin, ST562 caused 12% (53/440) of melioidosis cases, a proportion that increased during the study period. We analyzed 2 clusters of cases with epidemiologic links and used genomic analysis to identify previously unassociated cases. We found that ST562 isolates from Hainan Province, China, and Pingtung County, Taiwan, were distantly related to ST562 strains from Australia. Temporal genomic analysis suggested a single ST562 introduction into the Darwin region in ≈1988. The origin and transmission mode of ST562 into Australia remain uncertain.     

Melioidosis in Traveler from Africa to Spain

The worldwide epidemiology of melioidosis is changing. We describe a case of acute melioidosis in Spain in a patient who had traveled to Africa. A novel sequence type of Burkholderia pseudomallei was identified in this patient. Clinicians should be aware of the possibility of melioidosis in travelers returning from melioidosis-nonendemic regions.     

Melioidosis: an emerging infection in Taiwan?

From January 1982 to May 2000, 17 infections caused by Burkholderia pseudomallei were diagnosed in 15 patients in Taiwan; almost all the infections were diagnosed from 1994 to May 2000. Of the 15 patients, 9 (60%) had underlying diseases, and 10 (67%) had bacteremic pneumonia. Thirteen (76%) episodes of infection were considered indigenous. Four patients died of melioidosis. Seventeen B. pseudomallei isolates, recovered from eight patients from November 1996 to May 2000, were analyzed to determine their in vitro susceptibilities to 14 antimicrobial agents, cellular fatty acid and biochemical reaction profiles, and randomly amplified polymorphic DNA patterns. Eight strains (highly related isolates) were identified. All isolates were arabinose non-assimilators and were susceptible to amoxicillin-clavulanate, piperacillin-tazobactam, imipenem, and meropenem. No spread of the strain was documented.     

Soil characteristics influencing the spatial distribution of melioidosis in Far North Queensland,Australia

The environmental bacterium, Burkholderia pseudomallei, is responsible for the potentially fatal disease melioidosis. Factors responsible for the temporospatial distribution of cases are incompletely understood, although a combination of rainfall, groundwater levels and the physicochemical properties of soil are important. The distribution of culture-positive cases of melioidosis from 1996 to 2016 in Far North Queensland, Australia, was investigated to determine the association with different soil types and landforms in Cairns, the region''s largest city. Cases were clustered on alluvial fan landforms of strongly bleached gradational textured and yellow massive gradational textured soils indicating these soils are more suitable for B. pseudomallei and risk of melioidosis infection is higher in these areas, cases were less frequent on other soil types on alluvial fan landforms (despite comparable population density) and beach ridges. This indicates that the combination of these soils might be more suitable for B. pseudomallei, increasing the risk of disease in these locations. Sociodemographic characterisics of the population in cluster locations were considered. Knowledge of local soil characteristics may help predict cases of melioidosis and inform public health strategies to prevent the disease. Because melioidosis case clusters were identified, testing for the presence of B. pseudomallei across the study area is a useful target of future research.Key words: Melioidosis, spatial modeling     

The use of bone marrow culture for the diagnosis of melioidosis

We have evaluated prospectively the contribution of bone marrow culture to the diagnosis of melioidosis. Bone marrow (BMC) and blood cultures (BC) were collected concurrently from 105 patients with suspected acute, severe melioidosis. 67 patients were subsequently proved to have the disease whilst other significant organisms were isolated from these specimens in 5 cases. Overall, 67.2% of BC and 64.2% of BMC from melioidosis patients grew Pseudomonas pseudomallei. Time to positivity did not differ significantly in paired BC and BMC specimens. These results do not support the routine use of BMC in the diagnosis of acute, severe melioidosis. In one patient with pulmonary melioidosis, however, blood cultures were repeatedly negative, whilst bone marrow grew P. pseudomallei, and this preceded the development of a distant focus of infection. This suggests that culture of bone-marrow may be of value in certain blood culture-negative patients with melioidosis.     

Clinical presentation of melioidosis in Queensland, Australia

A retrospective study was performed on culture-positive patients (n = 57) with melioidosis presenting to the Townsville Hospital to define the epidemiology of the disease in Queensland, Australia. Mortality was 25% (n = 14) with a 9% (n = 5) relapse rate. At presentation, primary organs involved included the lungs (58%; n = 33), genitourinary system (11%; n = 6), skin and soft tissue (9%; n = 5), bone and joints (4%; n = 2), central nervous system (4%; n = 2), mycotic aneurysm (2%; n = 1) and peritonitis (2%; n = 1). No focus of infection could be identified in 12% of cases (n = 7). There was no significant difference in the clinical presentation of melioidosis in Queensland compared with the Northern Territory. Regional trends in the clinical presentation of melioidosis in Australia compared with Southeast Asia were confirmed. Risk factors for disease included diabetes (42%), excess alcohol consumption (42%), chronic lung disease (26%), immunosuppressive drug use (12%), renal disease (11%), malignancy (7%) and autoimmune disease (5%). No risk factors were identifiable in 18% of cases. The presence of multiple risk factors for melioidosis was not significantly associated with increased mortality (P > 0.05).     

Consensus on the Development of Vaccines against Naturally Acquired Melioidosis

Several candidates for a vaccine against Burkholderia pseudomallei, the causal bacterium of melioidosis, have been developed, and a rational approach is now needed to select and advance candidates for testing in relevant nonhuman primate models and in human clinical trials. Development of such a vaccine was the topic of a meeting in the United Kingdom in March 2014 attended by international candidate vaccine developers, researchers, and government health officials. The focus of the meeting was advancement of vaccines for prevention of natural infection, rather than for protection from the organism’s known potential for use as a biological weapon. A direct comparison of candidate vaccines in well-characterized mouse models was proposed. Knowledge gaps requiring further research were identified. Recommendations were made to accelerate the development of an effective vaccine against melioidosis.     

Melioidosis in animals, Thailand, 2006-2010

We retrospectively estimated the incidence of culture-proven melioidosis in animals in Thailand during 2006-2010. The highest incidence was in goats (1.63/100,000/year), followed by incidence in pigs and cattle. The estimated incidence of melioidosis in humans in a given region paralleled that of melioidosis in goats.     

Association of Melioidosis Incidence with Rainfall and Humidity,Singapore, 2003–2012

Soil has been considered the natural reservoir for the bacterium Burkholderia pseudomallei, which causes melioidosis. We examined 550 melioidosis cases that occurred during a 10-year period in the highly urbanized city of Singapore, where soil exposure is rare, and found that rainfall and humidity levels were associated with disease incidence.     

Melioidosis Caused by Burkholderia pseudomallei in Drinking Water,Thailand, 2012

We identified 10 patients in Thailand with culture-confirmed melioidosis who had Burkholderia pseudomallei isolated from their drinking water. The multilocus sequence type of B. pseudomallei from clinical specimens and water samples were identical for 2 patients. This finding suggests that drinking water is a preventable source of B. pseudomallei infection.     

Clinical,Environmental, and Serologic Surveillance Studies of Melioidosis in Gabon, 2012–2013

Burkholderia pseudomallei, an environmental gram-negative bacillus, is the causative agent of melioidosis and a bio-threat agent. Reports of B. pseudomallei isolation from soil and animals in East and West Africa suggest that melioidosis might be more widely distributed than previously thought. Because it has been found in equatorial areas with tropical climates, we hypothesized that B. pseudomallei could exist in Gabon. During 2012–2013, we conducted a seroprevalance study in which we set up microbiology facilities at a large clinical referral center and prospectively screened all febrile patients by conducting blood cultures and testing for B. pseudomallei and related species; we also determined whether B. pseudomallei could be isolated from soil. We discovered a novel B. pseudomallei sequence type that caused lethal septic shock and identified B. pseudomallei and B. thailandensis in the environment. Our data suggest that melioidosis is emerging in Central Africa but is unrecognized because of the lack of diagnostic microbiology facilities.     

A retrospective serological survey of Royal Marines previously exposed to Pseudomonas pseudomallei in South East Asia

Following the suggestion that it was possible that cases of melioidosis amongst those who had been exposed abroad in the past, might be escaping notice, 487 Royal Marines were examined by indirect haemagglutination studies. Four hundred and eleven of these subjects had served for variable times in areas where melioidosis has been known to occur in Indonesia and Malaya, between 1960 and 1974, occupied in activities in the jungle and paddy fields during which exposure to the disease was to be expected. No evidence of residual subclinical melioidosis was found and it seems unlikely that recrudescent disease will prove to be a problem in the future for English servicemen who have been in South East Asia.     

Burkholderia pseudomallei in Unchlorinated Domestic Bore Water, Tropical Northern Australia

To determine whether unchlorinated bore water in northern Australia contained Burkholderia pseudomallei organisms, we sampled 55 bores; 18 (33%) were culture positive. Multilocus sequence typing identified 15 sequence types. The B. pseudomallei sequence type from 1 water sample matched a clinical isolate from a resident with melioidosis on the same property.     

Chlorination and pH of drinking water do not correlate with rates of melioidosis in the Northern Territory, Australia

Prompted by 2 outbreaks of melioidosis with fatalities linked to culture-positive drinking water, we theorized that there may be a correlation between low drinking water pH or lack of chlorination and the rate of melioidosis in rural communities in tropical Australia. However, following adjustment for rainfall, such associations were not apparent in a multivariate regression model.     

Imported Melioidosis in South Korea: A Case Series with a Literature Review

Objectives

Melioidosis is a potentially fatal infectious disease caused by the environmental anaerobic Gram-negative bacillus Burkholderia pseudomallei. Melioidosis is endemic to areas of northern Australia and Southeast Asia. With increasing international travel and migration, imported cases of melioidosis are being reported regularly. Here, we summarize the 11 cases of melioidosis reported in South Korea from 2003 to 2014.

Methods

Tracing epidemiological investigations were performed on every patient reported to the National Surveillance System since 2011. A systematic literature search was performed to identify melioidosis cases that occurred prior to 2011.

Results

The overall fatality rate was 36.4%. All the patients had visited Southeast Asia where melioidosis is endemic. The stay in the endemic region ranged from 4 days to 20 years. Of the seven patients who developed initial symptoms after returning to South Korea, the time interval between returning to South Korea and symptom onset ranged from 1 day to 3 years. The remaining four patients developed symptoms during their stay in the endemic region and were diagnosed with melioidosis in South Korea. Seven (63.6%) patients possessed at least one risk factor, all of whom were diabetic. Pneumonia was the most frequent clinical manifestation, but the patients showed a wide spectrum of clinical features, including internal organ abscesses, a mycotic aneurysm of the aorta, and coinfection with tuberculosis.

Conclusion

An early diagnosis and initiation of the appropriate antibiotics can reduce the mortality of melioidosis. Consequently, increased awareness of the risk factors and clinical features of melioidosis is required.     

Preliminary report on the northern Australian melioidosis environmental surveillance project

An environmental surveillance programme was developed to determine whether water supplies could be a source of Burkholderia pseudomallei as noted during previous melioidosis outbreak investigations. Water supplies to communities in the three northern Australian jurisdictions (Western Australia, Northern Territory and Queensland) were sampled periodically during 2001 and 2002. Water and soil samples were collected from communities known to have had recent culture-positive melioidosis cases and nearby communities where no cases had been diagnosed. Clinical isolates of B. pseudomallei obtained from northern Australian patients during 2001 and 2002 were compared with the environmental B. pseudomallei isolates by ribotyping and pulsed-field gel electrophoresis. B. pseudomallei was isolated from 11 distinct locations, all in the Northern Territory, seven of which were associated with culture-positive melioidosis cases (>1 case at three locations). Water was implicated as a possible environmental source of melioidosis in six locations. A variety of free-living amoebae including Acanthamoeba and Hartmannella spp. that are potential hosts to B. pseudomallei were recovered from environmental specimens. Culturable B. pseudomallei was not found to be widely dispersed in the environments sampled.     

Immunization with the recombinant Burkholderia pseudomallei outer membrane protein Omp85 induces protective immunity in mice

Burkholderia pseudomallei is resistant to a wide range of antibiotics, leading to relapse and recrudescence of melioidosis after cessation of antibiotic therapy. More effective immunotherapies are needed for better management of melioidosis. We evaluated the prophylactic potential of the immunogenic outer membrane protein Omp85 as a vaccine against murine melioidosis. Immunization of BALB/c mice with recombinant Omp85 (rOmp85) triggered a Th2-type immune response. Up to 70% of the immunized animals were protected against infectious challenge of B. pseudomallei with reduced bacterial load in extrapulmonary organs. Mouse anti-rOmp85 promoted complement-mediated killing and opsonophagocytosis of B. pseudomallei by human polymorphonuclear cells. In conclusion, we demonstrated that B. pseudomallei Omp85 is potentially able to induce protective immunity against melioidosis.     

35例类鼻疽病例临床特点分析

目的分析类鼻疽的临床特点,并探讨其诊断及治疗的方法。方法回顾性分析某院2012年3月—2017年2月收治的有明确病原学依据的35例类鼻疽患者。结果 35例类鼻疽患者在入院时2例(5.7%)因有外院培养结果而确诊,3例(8.6%)高度疑似患者主要有相对典型的临床特点,误诊30例(85.7%),疑似患者入院后均经各种标本培养检出类鼻疽伯克霍尔德菌确诊;采用抗感染、外科穿刺引流(11.4%)及手术(20.0%)治疗,病情好转或痊愈26例(74.3%),放弃治疗2例(5.7%),死亡7例(20.0%)。临床首发症状以发热(88.6%)最常见,其次为咳嗽(34.3%)、气促(28.6%)、腹痛(14.6%)、上下肢痛(11.4%)、关节痛(5.7%);感染部位居前五位的分别为血液(85.7%)、肺(54.3%)、脾(20.0%)、皮肤软组织(20.0%)、肝(14.3%);以血培养出类鼻疽伯克霍尔德菌最为常见,占85.7%,其次为各种穿刺液(37.1%)、痰(20.0%)。结论类鼻疽的临床特点复杂多样,误诊率高,早期确诊和及时、合理、足疗程的治疗可降低病死率和复发率。     

Burkholderia pseudomallei and Burkholderia mallei vaccines: Are we close to clinical trials?

B. pseudomallei is the cause of melioidosis, a serious an often fatal disease of humans and animals. The closely related bacterium B. mallei, which cases glanders, is considered to be a clonal derivative of B. pseudomallei. Both B. pseudomallei and B. mallei were evaluated by the United States and the former USSR as potential bioweapons. Much of the effort to devise biodefence vaccines in the past decade has been directed towards the identification and formulation of sub-unit vaccines which could protect against both melioidosis and glanders. A wide range of proteins and polysaccharides have been identified which protective immunity in mice. In this review we highlight the significant progress that has been made in developing glycoconjugates as sub-unit vaccines. We also consider some of the important the criteria for licensing, including the suitability of the “animal rule” for assessing vaccine efficacy, the protection required from a vaccine and the how correlates of protection will be identified. Vaccines developed for biodefence purposes could also be used in regions of the world where naturally occurring disease is endemic.     

Changing epidemiology of melioidosis? A case of acute pulmonary melioidosis with fatal outcome imported from Brazil

Melioidosis is an infectious disease caused by Burkholderia pseudomallei. It is endemic in South East Asia and tropical regions of Northern Australia. Sporadic cases have been described elsewhere. In this article we present a case of acute pulmonary melioidosis with fatal outcome imported from Brazil. The most common pathogen causing severe community-acquired pneumonia in Brazil is Streptococcus pneumoniae. Other possible pathogens include Legionella spp., Mycoplasma pneumonia, Gram-negative rods and viruses. There are few reports of melioidosis in the Americas. This article represents the second known human case of melioidosis from Brazil. Recognition of melioidosis as a possible cause of severe pneumonia, even if a patient has not been travelling in a highly endemic area, is important because of the therapeutic consequences. The epidemiology of melioidosis will be reviewed.