195 research outputs found

    Epidemiology of camel contagious ecthyma and molecular detection of the pathogen in Arero district, Ethiopia

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    Even though camels (Camelus dromedarius) were traditionally believed to be resistant to most livestock diseases, research has demonstrated that they are susceptible to a large number of infectious agents. Based on the clinical appearance of typical lesions, camel contagious ecthyma (CCE), caused by a Parapoxvirus (PPV), is thought to be one of the most common viral diseases of camels in Ethiopia. A cross-sectional study was conducted from November 2013 to April 2014 in the Arero district of Borena Zone, Oromia Regional State of Ethiopia to investigate the epidemiological aspect of CCE and molecularly identify the causative agent. A polymerase chain reaction (PCR) based on B2L gene-specific primers of PPV was used for the confirmatory diagnosis of the CCE virus from the skin lesion of camels showing suspected clinical signs of CCE infection. Eighty-seven percent (87.0%) of camel owners reported the occurrence of CCE outbreaks in their herds in the past year (a year preceding the start of the study). The overall morbidity and mortality rates attributed to CCE were 20% (95% CI: 11– 36%) and 6.3% (95 % CI: 5.2 –7.6%), respectively. Younger camels had higher odds of becoming affected by CCE than adults [OR=3.44 (95 % CI: 2.29 –4.09)] and the difference was statistically significant. Confirmatory diagnosis of the suspected cases using conventional PCR generated the expected amplification product size of 1200bp for one of the samples. Therefore, the study confirms the presence and importance of CCE in Ethiopia and establishes the basis for further investigation

    Molecular epidemiology and pathogenomics of extended-spectrum beta-lactamase producing- Escherichia coli and - Klebsiella pneumoniae isolates from bulk tank milk in Tennessee, USA

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    IntroductionThe rise in extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in dairy cattle farms poses a risk to human health as they can spread to humans through the food chain, including raw milk. This study was designed to determine the status, antimicrobial resistance, and pathogenic potential of ESBL-producing -E. coli and -Klebsiella spp. isolates from bulk tank milk (BTM).MethodsThirty-three BTM samples were collected from 17 dairy farms and screened for ESBL-E. coli and -Klebsiella spp. on CHROMagar ESBL plates. All isolates were confirmed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and subjected to antimicrobial susceptibility testing and whole genome sequencing (WGS).ResultsTen presumptive ESBL-producing bacteria, eight E. coli, and two K. pneumoniae were isolated. The prevalence of ESBL-E. coli and -K. pneumoniae in BTM was 21.2% and 6.1%, respectively. ESBL-E. coli were detected in 41.2% of the study farms. Seven of the ESBL-E. coli isolates were multidrug resistant (MDR). The two ESBL-producing K. pneumoniae isolates were resistant to ceftriaxone. Seven ESBL-E. coli strains carry the blaCTX-M gene, and five of them co-harbored blaTEM-1. ESBL-E. coli co-harbored blaCTX-M with other resistance genes, including qnrB19, tet(A), aadA1, aph(3’’)-Ib, aph(6)-Id), floR, sul2, and chromosomal mutations (gyrA, gyrB, parC, parE, and pmrB). Most E. coli resistance genes were associated with mobile genetic elements, mainly plasmids. Six sequence types (STs) of E. coli were detected. All ESBL-E. coli were predicted to be pathogenic to humans. Four STs (three ST10 and ST69) were high-risk clones of E. coli. Up to 40 virulence markers were detected in all E. coli isolates. One of the K. pneumoniae was ST867; the other was novel strain. K. pneumoniae isolates carried three types of beta-lactamase genes (blaCTX-M, blaTEM-1 and blaSHV). The novel K. pneumoniae ST also carried a novel IncFII(K) plasmid ST.ConclusionDetection of high-risk clones of MDR ESBL-E. coli and ESBL-K. pneumoniae in BTM indicates that raw milk could be a reservoir of potentially zoonotic ESBL-E. coli and -K. pneumoniae

    Mainstreaming Efficient Legume Seed Systems in Eastern Africa: Challenges, opportunities and contributions towards improved livelihoods

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    Legumes are important components of sustainable farming systems. They are useful to diversify and intensify cropping systems as double, catch, relay and intercrops; fix ‘free’ nitrogen to soils from the atmosphere and improve soil health that boost cereal crop yields; act as rotation crops for breaking disease and pest cycles; increase and diversify smallholder incomes (and hence buffer them from the effects of price, pest and climate-related production fluctuations); enhance quality of household diets because of their higher protein and micro-nutrient content compared with starch-based staple cereal crops; and provide good sources of animal feed (high protein crop residues and byproducts) and low carbon footprint, mitigating climate change..

    Mainstreaming Efficient Legume Seed Systems in Eastern Africa: Challenges, opportunities and contributions towards improved livelihoods

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    Legumes are important components of sustainable farming systems. They are useful to diversify and intensify cropping systems as double, catch, relay and intercrops; fix ‘free’ nitrogen to soils from the atmosphere and improve soil health that boost cereal crop yields; act as rotation crops for breaking disease and pest cycles; increase and diversify smallholder incomes (and hence buffer them from the effects of price, pest and climate-related production fluctuations); enhance quality of household diets because of their higher protein and micro-nutrient content compared with starch-based staple cereal crops; and provide good sources of animal feed (high protein crop residues and byproducts) and low carbon footprint, mitigating climate change..

    Facile Preparation of Flavinium Organocatalysts

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    We developed a safe, simple, inexpensive, and environmentally benign method for preparing N(5)-ethylated flavinium organocatalysts without using any hazardous reagents or inert conditions as previously required. 5-Ethyl-3-methyllumiflavinium cation was prepared from its reduced form by NaNO2-free aerobic oxidation, which was subsequently extracted onto commercial cation-exchange resins under NaClO4-free conditions. The resulting resin-immobilized flavinium salts were found to be effective organocatalysts for aerobic oxidation reactions

    Advanced flavin catalysts elaborated with polymers

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    A variety of biological redox reactions are mediated by flavoenzymes due to the unique redox activity of isoalloxazine ring systems, which are found in flavin cofactors. In the field of synthetic organic chemistry, the term “flavin” is generally used for not only isoalloxazines but also related molecules including their isomers and some analogues, and those having catalytic activity are called flavin catalyst. Flavin catalysts are typically metal-free, and their catalytic activity can be readily accessed using mild terminal oxidants such as H2O2 and O2; therefore, redox reactions with these compounds have great promise as alternatives to reactions with conventional metal catalysts for the sustainable production of important chemicals. We recently became interested in using polymers for the development of flavin catalysts, especially to improve their practicality and advance the field of catalysis. Here, we summarize our recent research on such flavin-polymer collaborations including the development of facile preparation methods for flavin catalysts using polymers, readily reusable polymer-supported flavin catalysts, and flavin-peptide-polymer hybrids that can catalyze the first flavoenzyme-mimetic aerobic oxygenation reactions

    Xpert MTB/RIF and Xpert Ultra assays for screening for pulmonary tuberculosis and rifampicin resistance in adults, irrespective of signs or symptoms

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    Background Tuberculosis is a leading cause of infectious disease‐related death and is one of the top 10 causes of death worldwide. The World Health Organization (WHO) recommends the use of specific rapid molecular tests, including Xpert MTB/RIF or Xpert Ultra, as initial diagnostic tests for the detection of tuberculosis and rifampicin resistance in people with signs and symptoms of tuberculosis. However, the WHO estimates that nearly one‐third of all active tuberculosis cases go undiagnosed and unreported. We were interested in whether a single test, Xpert MTB/RIF or Xpert Ultra, could be useful as a screening test to close this diagnostic gap and improve tuberculosis case detection. Objectives To estimate the accuracy of Xpert MTB/RIF and Xpert Ultra for screening for pulmonary tuberculosis in adults, irrespective of signs or symptoms of pulmonary tuberculosis in high‐risk groups and in the general population. Screening "irrespective of signs or symptoms" refers to screening of people who have not been assessed for the presence of tuberculosis symptoms (e.g. cough). To estimate the accuracy of Xpert MTB/RIF and Xpert Ultra for detecting rifampicin resistance in adults screened for tuberculosis, irrespective of signs and symptoms of pulmonary tuberculosis in high‐risk groups and in the general population. Search methods We searched 12 databases including the Cochrane Infectious Diseases Group Specialized Register, MEDLINE and Embase, on 19 March 2020 without language restrictions. We also reviewed reference lists of included articles and related Cochrane Reviews, and contacted researchers in the field to identify additional studies. Selection criteria Cross‐sectional and cohort studies in which adults (15 years and older) in high‐risk groups (e.g. people living with HIV, household contacts of people with tuberculosis) or in the general population were screened for pulmonary tuberculosis using Xpert MTB/RIF or Xpert Ultra. For tuberculosis detection, the reference standard was culture. For rifampicin resistance detection, the reference standards were culture‐based drug susceptibility testing and line probe assays. Data collection and analysis Two review authors independently extracted data using a standardized form and assessed risk of bias and applicability using QUADAS‐2. We used a bivariate random‐effects model to estimate pooled sensitivity and specificity with 95% credible intervals (CrIs) separately for tuberculosis detection and rifampicin resistance detection. We estimated all models using a Bayesian approach. For tuberculosis detection, we first estimated screening accuracy in distinct high‐risk groups, including people living with HIV, household contacts, people residing in prisons, and miners, and then in several high‐risk groups combined. Main results We included a total of 21 studies: 18 studies (13,114 participants) evaluated Xpert MTB/RIF as a screening test for pulmonary tuberculosis and one study (571 participants) evaluated both Xpert MTB/RIF and Xpert Ultra. Three studies (159 participants) evaluated Xpert MTB/RIF for rifampicin resistance. Fifteen studies (75%) were conducted in high tuberculosis burden and 16 (80%) in high TB/HIV‐burden countries. We judged most studies to have low risk of bias in all four QUADAS‐2 domains and low concern for applicability. Xpert MTB/RIF and Xpert Ultra as screening tests for pulmonary tuberculosis In people living with HIV (12 studies), Xpert MTB/RIF pooled sensitivity and specificity (95% CrI) were 61.8% (53.6 to 69.9) (602 participants; moderate‐certainty evidence) and 98.8% (98.0 to 99.4) (4173 participants; high‐certainty evidence). Of 1000 people where 50 have tuberculosis on culture, 40 would be Xpert MTB/RIF‐positive; of these, 9 (22%) would not have tuberculosis (false‐positives); and 960 would be Xpert MTB/RIF‐negative; of these, 19 (2%) would have tuberculosis (false‐negatives). In people living with HIV (1 study), Xpert Ultra sensitivity and specificity (95% CI) were 69% (57 to 80) (68 participants; very low‐certainty evidence) and 98% (97 to 99) (503 participants; moderate‐certainty evidence). Of 1000 people where 50 have tuberculosis on culture, 53 would be Xpert Ultra‐positive; of these, 19 (36%) would not have tuberculosis (false‐positives); and 947 would be Xpert Ultra‐negative; of these, 16 (2%) would have tuberculosis (false‐negatives). In non‐hospitalized people in high‐risk groups (5 studies), Xpert MTB/RIF pooled sensitivity and specificity were 69.4% (47.7 to 86.2) (337 participants, low‐certainty evidence) and 98.8% (97.2 to 99.5) (8619 participants, moderate‐certainty evidence). Of 1000 people where 10 have tuberculosis on culture, 19 would be Xpert MTB/RIF‐positive; of these, 12 (63%) would not have tuberculosis (false‐positives); and 981 would be Xpert MTB/RIF‐negative; of these, 3 (0%) would have tuberculosis (false‐negatives). We did not identify any studies using Xpert MTB/RIF or Xpert Ultra for screening in the general population. Xpert MTB/RIF as a screening test for rifampicin resistance Xpert MTB/RIF sensitivity was 81% and 100% (2 studies, 20 participants; very low‐certainty evidence), and specificity was 94% to 100%, (3 studies, 139 participants; moderate‐certainty evidence). Authors' conclusions Of the high‐risks groups evaluated, Xpert MTB/RIF applied as a screening test was accurate for tuberculosis in high tuberculosis burden settings. Sensitivity and specificity were similar in people living with HIV and non‐hospitalized people in high‐risk groups. In people living with HIV, Xpert Ultra sensitivity was slightly higher than that of Xpert MTB/RIF and specificity similar. As there was only one study of Xpert Ultra in this analysis, results should be interpreted with caution. There were no studies that evaluated the tests in people with diabetes mellitus and other groups considered at high‐risk for tuberculosis, or in the general population

    Heterocyclic Hydroperoxides in Selective Oxidations

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