The Cambodian Mekong floodplain under future development plans and climate change

| openaire: EC/H2020/819202/EU//SOS.aquaterra Funding Information: Financial support. This research has been supported by the Publisher Copyright: © Copyright:Water infrastructure development is considered necessary to drive economic growth in the Mekong region of mainland Southeast Asia. Yet the current understanding of hydrological and flood pattern changes associated with infrastructural development still contains several knowledge gaps, such as the interactions between multiple drivers, which may have serious implications for water management, agricultural production, and ecosystem services. This research attempts to conduct a cumulative assessment of basin-wide hydropower dam construction and irrigation expansion, as well as climate change, implications on discharge, and flood changes in the Cambodian Mekong floodplain. These floodplains offer important livelihoods for a considerable part of the 6.4 million people living on them, as they are among the most productive ecosystems in the world - driven by the annual flood pulse. To assess the potential future impacts, we used an innovative combination of three models: Mekong basin-wide distributed hydrological model IWRM-VMod, with the Mekong delta 1D flood propagation model MIKE-11 and 2D flood duration and extent model IWRM-Sub enabling detail floodplain modelling. We then ran scenarios to approximate possible conditions expected by around 2050. Our results show that the monthly and seasonal hydrological regimes (discharges, water levels, and flood dynamics) will be subject to substantial alterations under future development scenarios. Projected climate change impacts are expected to decrease dry season flows and increase wet season flows, which is in opposition to the expected alterations under development scenarios that consider both hydropower and irrigation. The likely impact of decreasing water discharge in the early wet season (up to -30 %) will pose a critical challenge to rice production, whereas the likely increase in water discharge in the mid-dry season (up to +140 %) indicates improved water availability for coping with drought stresses and sustaining environmental flows. At the same time, these changeswould have drastic impacts on total flood extent, which is projected to decline by around 20 %, having potentially negative impacts on floodplain productivity and aquaculture, whilst reducing the flood risk to more densely populated areas. Our findings demonstrate the substantial changes that planned infrastructural development will have on the area, potentially impacting important ecosystems and people's livelihoods, calling for actions to mitigate these changes as well as planning potential adaptation strategies.Peer reviewe

Diagnostic accuracy of the InBiOS AMD rapid diagnostic test for the detection of Burkholderia pseudomallei antigen in grown blood culture broth

To assess the diagnostic and operational performance of the InBiOS AMD rapid diagnostic test (RDT) (Seattle, USA) for the detection of B. pseudomallei in grown blood culture broth. The InBiOS RDT is a lateral flow immunoassay in a strip format detecting B. pseudomallei capsular polysaccharide in culture fluids, marketed for research only. Broth of blood culture bottles (BacT/Alert, bioMérieux, Marcy L'Etoile, France) sampled in adult patients at the Sihanouk Hospital Center of HOPE, Phnom Penh, Cambodia, during 2010-2017 and stored at - 80 °C was tested. They included samples grown with B. pseudomallei (n = 114), samples with no growth (n = 12), and samples with growth of other pathogens (n = 139, among which Burkholderia cepacia (n = 5)). Diagnostic sensitivity and specificity were 96.5% [95% confidence interval (CI): 91.3-98.6%] and 100% [CI: 97.5-100%] respectively. Background clearance and line intensities were good and very good. The RDT's test strip, not housed in a cassette, caused difficulties in manipulation and biosafety. The centrifugation step prescribed by the procedure challenged biosafety, but processing of 19 B. pseudomallei samples without centrifugation showed similar results for line intensity and background clearance, compared to centrifugation. The InBiOS RDT showed excellent accuracy for detection of B. pseudomallei in grown blood culture broth. Provided operational adaptations such as cassette housing, it has the potential to reduce time to diagnosis of melioidosis.status: publishe

Slow growth of Burkholderia pseudomallei compared to other pathogens in an adapted blood culture system in Phnom Penh, Cambodia

PURPOSE: Burkholderia pseudomallei is a key pathogen causing bloodstream infections at Sihanouk Hospital Center of Hope, Phnom Penh, Cambodia. Here, visual instead of automated detection of growth of commercial blood culture bottles is done. The present study assessed the performance of this system. METHODOLOGY: Blood culture sets, consisting of paired adult aerobic and anaerobic bottles (bioMérieux, FA FAN 259791 and FN FAN 252793) were incubated in a standard incubator for 7 days after reception. Each day, the bottle growth indicator was visually inspected for colour change indicating growth. Blind subculture was performed from the aerobic bottle at day 3. RESULTS: From 2010 to 2015, 11  671 sets representing 10  389 suspected bloodstream infection episodes were documented. In 1058 (10.2  %) episodes, pathogens grew; they comprised Escherichia coli (31.7 %), Salmonella Paratyphi A (13.9 %), B. pseudomallei (8.5 %), Staphylococcus aureus (7.8 %) and Klebsiella pneumoniae (7.0 %). Blind subculture yielded 72 (4.1  %) pathogens, mostly (55/72, 76.4 %) B. pseudomallei. Cumulative proportions of growth at day 2 were as follows: E. coli: 85.0 %, Salmonella Paratyphi A: 85.0 %, K. pneumoniae: 76.3  % and S. aureus: 52.2  %; for B. pseudomallei, this was only 4.0  %, which increased to 70.1  % (70/99) at day 4 mainly by detection on blind subculture (55/99). Compared to the anaerobic bottles, aerobic bottles had a higher yield and a shorter time-to-detection, particularly for B. pseudomallei. CONCLUSIONS: Visual inspection for growth of commercial blood culture bottles in a low-resource setting provided satisfactory yield and time-to-detection. However, B. pseudomallei grew slowly and was mainly detected by blind subculture. The aerobic bottle outperformed the anaerobic bottle.status: publishe

Presence of black and red colored test lines.

<p>Samples applied to both tests (<i>Salmonella</i> Ag Rapid Test, Creative diagnostics) contained <i>Salmonella</i> Enteritidis and both were scored as a positive test result. The test above shows a red colored control line and a black colored test line. The picture below shows a red colored control and test line.</p

Variable background clearance.

<p>Both tests shown (Standard Diagnostics Bioline One Step <i>Salmonella</i> Typhi Ag Rapid Detection Kit) with the presence of a control line and absence of a test line, show a negative test result. Background clearance is scored poor for the test above (more reddish) and good for the test below.</p

Diagnostic accuracy of antigen-based immunochromatographic rapid diagnostic tests for the detection of <i>Salmonella</i> in blood culture broth

<div><p>Background</p><p>In low resource settings, <i>Salmonella</i> serovars frequently cause bloodstream infections. This study investigated the diagnostic performance of immunochromatographic rapid diagnostic tests (RDTs), which detect <i>Salmonella</i> antigens, when applied to stored grown blood culture broth.</p><p>Material/Methods</p><p>The SD Bioline One Step <i>Salmonella</i> Typhi Ag Rapid Detection Kit (Standard Diagnostics, Republic of Korea), marketed for the detection of <i>Salmonella enterica</i> serovar Typhi (<i>Salmonella</i> Typhi) in stool and the <i>Salmonella</i> Ag Rapid Test (Creative Diagnostics, USA), marketed for the detection of all <i>Salmonella</i> serotypes in stool, were selected for evaluation based on a pre-test evaluation of six RDT products. The limits of detection (LOD) for culture suspensions were established and the selected RDT products were assessed on 19 freshly grown spiked blood culture broth samples and 413 stored clinical blood culture broth samples, collected in Cambodia and the Democratic Republic of the Congo.</p><p>Results</p><p>The LOD of both products was established as 10⁷−10⁸ CFU/ml. When applied to clinical blood culture broth samples, the diagnostic sensitivity and specificity of the SD Bioline RDT were respectively 100% and 79.7% for the detection of <i>Salmonella</i> Typhi; 94.4% (65/69) of false-positive results were caused by <i>Salmonella</i> Enteritidis. When considering the combined detection of <i>Salmonella</i> Typhi and Enteritidis (both group D <i>Salmonella</i>), sensitivity and specificity were 97.9% and 98.5% respectively. For Creative Diagnostics, diagnostic sensitivity was 78.3% and specificity 91.0% for all <i>Salmonella</i> serotypes combined; 88.3% (53/60) of false negative results were caused by <i>Salmonella</i> Paratyphi A.</p><p>Conclusions</p><p>When applied to grown blood culture broths, the SD Bioline RDT had a good sensitivity and specificity for the detection of <i>Salmonella</i> Typhi and <i>Salmonella</i> Enteritidis. The Creative Diagnostics product had a moderate sensitivity and acceptable specificity for the detection of all <i>Salmonella</i> serovars combined and needs further optimization. A RDT that reliably detects <i>Salmonella</i> Paratyphi A is needed.</p></div

Bacterial strains used for spiking blood culture bottles and corresponding rapid diagnostic test results.

<p>Bacterial strains used for spiking blood culture bottles and corresponding rapid diagnostic test results.</p

Determination of limit of detection and corresponding test line intensity for each rapid diagnostic test.

<p>Determination of limit of detection and corresponding test line intensity for each rapid diagnostic test.</p