Putrescine biosynthesis and export genes are essential for normal growth of avian pathogenic Escherichia coli

[Background] Avian pathogenic Escherichia coli (APEC) is the infectious agent of a wide variety of avian diseases, which causes substantial economic losses to the poultry industry worldwide. Polyamines contribute to the optimal synthesis of nucleic acids and proteins in bacteria. The objectives of this study were to investigate; i) whether APEC E. coli encodes the same systems for biosynthesis and uptake as described for E. coli K12 and ii) the role of polyamines during in vitro growth of an avian pathogenic E. coli strain (WT-ST117- O83:H4T).[Results] Following whole genome sequencing, polyamine biosynthesis and export genes present in E. coli MG1655 (K-12) were found to be identical in WT-ST117. Defined mutants were constructed in putrescine and spermidine biosynthesis pathways (ΔspeB, ΔspeC, ΔspeF, ΔspeB/C and ΔspeD/E), and in polyamines transport systems (ΔpotE, ΔyeeF, ΔpotABCD and ΔpotFGHI). Contrary to what was observed for MG1655, the ΔpotE-ST117 mutant was growth attenuated, regardless of putrescine supplementation. The addition of spermidine or orthinine restored the growth to the level of WT-ST117. Growth attenuation after induction of membrane stress by SDS suggested that PotE is involved in protection against this stress. The ΔspeB/C-ST117 mutant was also growth attenuated in minimal medium. The addition of putrescine or spermidine to the media restored growth rate to the wild type level. The remaining biosynthesis and transport mutants showed a growth similar to that of WT-ST117. Analysis by Ultra-High Performance Liquid Chromatography revealed that the ΔspeB/C mutant was putrescine-deficient, despite that the gene speF, which is also involved in the synthesis of putrescine, was expressed.[Conclusions] Deletion of the putrescine transport system, PotE, or the putrescine biosynthesis pathway genes speB/C affected in vitro growth of APEC (ST117- O83:H4) strain, but not E. coli MG1655, despite the high similarity of the genetic make-up of biosynthesis and transport genes. Therefore, blocking these metabolic reactions may be a suitable way to prevent APEC growth in the host without disturbing the commensal E. coli population.Priscila R. Guerra was supported by a scholarship from CAPES – Brazilian Federal Agency for Support and Evaluation of Graduate Education within the Ministry of Education of Brazil. This study received financial support from Spanish Ministry of Economy, Industry and Competitiveness (AGL2013–45431-R and AGL2016–78708-R), and from the Danish Council for Independent Research (Technology and Production), grant number DFF – 4184-00050. The sponsors had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe

A visão do envelhecimento, da velhice e do idoso veiculada por livros infanto-juvenis

Este estudo, de abordagem qualitativa e tipo descritivo-exploratório, analisa a visão do envelhecimento veiculada por livros infanto-juvenis. O caminho metodológico foi permeado pela seleção, aquisição e análise, utilizando-se a técnica de análise de conteúdo categorial por temática, de livros nacionais recomendados pelo Programa Nacional Biblioteca da Escola (PNBE), publicados entre 2003 e 2012, tendo em seu enredo a menção ao idoso e/ou à velhice e/ou ao envelhecimento de seres humanos. Identificaram-se duas grandes categorias temáticas, compostas por subcategorias: 1) aspectos biológicos na velhice, com as subcategorias senescência versus senilidade e mitos relacionados aos aspectos físicos dos idosos; e 2) aspectos psicossociais na velhice, com as subcategorias conhecimento e experiência de vida do idoso, intergeracionalidade, autorrealização na velhice, isolamento social, mitos relacionados à velhice e morte na velhice. Os resultados procuram contribuir para uma melhor utilização dos livros infanto-juvenis no processo educativo a respeito do tema envelhecimento, não só em termos de cidadania e civilidade como também em termos de educação em saúde

Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): Study protocol for a randomized controlled trial

Background: Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design: ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH(2)O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure <= 30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion: If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method.Hospital do Coracao (HCor) as part of the Program 'Hospitais de Excelencia a Servico do SUS (PROADI-SUS)'Brazilian Ministry of Healt

Espécies do gênero Helicobacter de importância em medicina veterinária: revisão de literatura

As bactérias do gênero Helicobacter são bacilos Gram negativos, helicoidais, que requerem uma atmosfera de microaerofilia para seu crescimento. Podem habitar tanto a mucosa gástrica quanto o interior das glândulas gástricas de animais assintomáticos ou com sinais clínicos de gastropatia. Esses pacientes podem apresentar quadros de dispepsia, gastrite crônica, erosões, ulcerações e até adenocarcinoma, ocasionado dor e desconforto abdominal. Devido à elevada prevalência dessa bactéria em diferentes espécies animais, torna-se importante conhecer asprincipais espécies envolvidas na infecção, bem como os principais métodos diagnósticos utilizados na medicina veterinária. Os métodos invasivos, os quais necessitam de endoscopia digestiva alta, são os mais empregados em medicina veterinária, incluem-se a histologia, oteste rápido da urease, a cultura bacteriana e os métodos moleculares de diagnóstico. Para fins de pesquisa, recomenda-se a associação de múltiplas técnicas para alcançar um diagnósticomais preciso. O objetivo do trabalho foi revisar os principais métodos diagnósticos invasivosempregados em medicina veterinária, bem como as principais espécies de Helicobacter que acometem os animais domésticos