Acid stress response in campylobacter jejuni

Dissertação de Mestrado Integrado em Medicina VeterináriaConsidering that the acid tolerance is an important virulence factor of foodborne pathogens and the expressive increasing of incidence of Campylobacter jejuni in recent years as etiologic agent of human campylobacteriosis, this work aimed to evaluate the ability of C. jejuni to survive under acid stress. Strains of different origins (reference, turkey isolates) and tolerance to particular stresses (acid and temperature) were tested for survival in liquid defined media with pH values of 5.0 and 7.0 adjusted with 1M HCl. Experimental conditions were performed at 2 different temperatures: 4 ºC and 37 ºC. C. jejuni cells were found to be very sensitive to acid stress at 37 ºC, whereas they were more resistant at 4 ºC. A strain effect was observed at 37 ºC. Temperature of 37 ºC combined with acid stress allowed a rapid decrease in the C. jejuni population, whereas low temperature (4ºC) considerably decreased the effect of acid stress. The survival curves were either described by the Weibull or traditional first-order model and goodness of fit of these models was investigated. Regression coefficients (R2), root mean square error (RMSE) and correlation plots suggestted that Weibull model produced a better fit to the data than the traditional model. Fluorescence Ratio Imaging Microscopy (FRIM) was used to determine intracellular pH (pHi) as an indicator of the physiological state of C. jejuni cells at the single cell level after treatment with hydrochloride acid (1M HCl, pH 4.0) in liquid defined medium. For all the tested strains pHi of healthy cells was found to be above 7.0. After exposure to HCl in liquid medium an immediate decline in pHi to 5.5 (detection limit) was observed in the majority of cells (75%) of one strain within 15 minutes. The FRIM results revealed that the subpopulations with pHi>5.5 increased for this strain, especially subpopulations with 5.5<pHi<6.0 and 6.0<pHi<6.5 following 200 min. of exposure to HCl. This indicates that some strains of C. jejuni may employ certain recovery strategies to extrude protons and to increase pHi.RESUMO - Considerando que a tolerância ao ácido é um importante factor de virulência de agentes patogénicos veiculados por alimentos, condicionando a sobrevivência dos microrganismos, e o expressivo aumento, nos últimos anos, da incidência de Campylobacter jejuni como agente etiológico de campilobacteriose humana, este trabalho teve como objectivo avaliar a capacidade do patogénico C. jejuni sobreviver em condições de stresse ácido. Estirpes de diferentes origens (referência, isolados de peru) sujeitas a diferentes factores de stresse (acidez e temperatura) foram testadas avaliando-se a sua sobrevivência em meio líquido (pH 5.0 e 7.0). As condições experimentais foram efectuadas a duas temperaturas diferentes: 4 ºC e 37 ºC. Células de C. jejuni mostraram-se muitos sensíveis a stresse ácido a 37 ºC, enquanto a 4 ºC foram mais resistentes. O efeito estirpe foi evidenciado a 37 ºC. A temperatura 37ºC em combinação com um pH 5.0 (stresse ácido) causou rápido decréscimo da população de C. jejuni, enquanto que a 4ºC o efeito do stresse ácido diminuiu consideravelmente. As curvas de sobrevivência foram descritas pelos modelos Weibull ou pelo modelo clássico de inactivação de primeira ordem, tendo-se concluído através dos coeficientes de regressão (R2), raízes quadradas do erro médio (RMSE) e gráficos de correlação que o modelo Weibull se adequa melhor aos dados apresentados que o modelo tradicionalmente utilizado. O racio da emissão de fluorescência medida pela técnica de microscopia óptica invertida foi utilizado para determinar o pH intracelular (pHi) como indicador do estado fisiológico das células de C. jejuni, a um nível celular único, após aplicação de um tratamento com ácido clorídrico (1M HCl, pH 4.0) em meio de cultura líquido. Para todas as estirpes testadas, o pHi de células saudáveis encontrava-se acima de 7.0. Após exposição a HCl em meio líquido, foi detectado para uma das estirpes, um decréscimo imediato do pHi para 5.5 (limite de detecção) na maioria das células observadas (75%) ao fim de 15 minutos. Os resultados da medição de fluorescência revelaram um aumento de subpopulações com pHi>5.5 para essa estirpe, nomeadamente subpopulações com 5.5<pHi<6.0 e 6.0<pHi<6.5 em 200 min. de exposição a HCl. Estes resultados indicam que algumas estirpes de C. jejuni poderão utilizar determinadas estratégias de recuperação para exteriorizar protões e elevar o pHi

ATLANTIC EPIPHYTES: a data set of vascular and non-vascular epiphyte plants and lichens from the Atlantic Forest

Epiphytes are hyper-diverse and one of the frequently undervalued life forms in plant surveys and biodiversity inventories. Epiphytes of the Atlantic Forest, one of the most endangered ecosystems in the world, have high endemism and radiated recently in the Pliocene. We aimed to (1) compile an extensive Atlantic Forest data set on vascular, non-vascular plants (including hemiepiphytes), and lichen epiphyte species occurrence and abundance; (2) describe the epiphyte distribution in the Atlantic Forest, in order to indicate future sampling efforts. Our work presents the first epiphyte data set with information on abundance and occurrence of epiphyte phorophyte species. All data compiled here come from three main sources provided by the authors: published sources (comprising peer-reviewed articles, books, and theses), unpublished data, and herbarium data. We compiled a data set composed of 2,095 species, from 89,270 holo/hemiepiphyte records, in the Atlantic Forest of Brazil, Argentina, Paraguay, and Uruguay, recorded from 1824 to early 2018. Most of the records were from qualitative data (occurrence only, 88%), well distributed throughout the Atlantic Forest. For quantitative records, the most common sampling method was individual trees (71%), followed by plot sampling (19%), and transect sampling (10%). Angiosperms (81%) were the most frequently registered group, and Bromeliaceae and Orchidaceae were the families with the greatest number of records (27,272 and 21,945, respectively). Ferns and Lycophytes presented fewer records than Angiosperms, and Polypodiaceae were the most recorded family, and more concentrated in the Southern and Southeastern regions. Data on non-vascular plants and lichens were scarce, with a few disjunct records concentrated in the Northeastern region of the Atlantic Forest. For all non-vascular plant records, Lejeuneaceae, a family of liverworts, was the most recorded family. We hope that our effort to organize scattered epiphyte data help advance the knowledge of epiphyte ecology, as well as our understanding of macroecological and biogeographical patterns in the Atlantic Forest. No copyright restrictions are associated with the data set. Please cite this Ecology Data Paper if the data are used in publication and teaching events. © 2019 The Authors. Ecology © 2019 The Ecological Society of Americ

Tuberculosis: integrated studies for a complex disease 2050

Tuberculosis (TB) has been a disease for centuries with various challenges [1]. Like other places where challenges and opportunities come together, TB challenges were the inspiration for the scientific community to mobilize different groups for the purpose of interest. For example, with the emergence of drug resistance, there has been a huge volume of research on the discovery of new medicines and drug delivery methods and the repurposing of old drugs [2, 3]. Moreover, to enhance the capacity to detect TB cases, studies have sought diagnostics and biomarkers, with much hope recently expressed in the direction of point-of-care tests [4]. Despite all such efforts as being highlighted in 50 Chapters of this volume, we are still writing about TB and thinking about how to fight this old disease–implying that the problem of TB might be complex, so calling the need for an integrated science to deal with multiple dimensions in a simultaneous and effective manner. We are not the first one; there have been proposed integrated platform for TB research, integrated prevention services, integrated models for drug screening, integrated imaging protocol, integrated understanding of the disease pathogenesis, integrated control models, integrated mapping of the genome of the pathogen, etc. [5–12], to name some. These integrated jobs date back decades ago. So, a question arises: why is there a disease named TB yet? It might be due to the fact that this integration has happened to a scale that is not global, and so TB remains to be a problem, especially in resource-limited settings. Hope Tuberculosis: Integrated Studies for a Complex Disease helps to globalize the integrated science of TB.info:eu-repo/semantics/publishedVersio

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P &lt; 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)