DSA - Posters/abstracts em congressos internacionais
URI permanente para esta coleção:
Navegar
Percorrer DSA - Posters/abstracts em congressos internacionais por assunto "Agentes Microbianos e Ambiente"
A mostrar 1 - 10 de 16
Resultados por página
Opções de ordenação
- Actividade antibacteriana de extractos de Planktothrix agardhii contra Staphylococcus aureusPublication . Menezes, Carina; Dias, ElsaA resistência de bactérias patogénicas à antibioterapia é um dos principais problemas de saúde pública, face à crescente ineficácia dos antibióticos no tratamento de doenças infeciosas. Assim, a pesquisa de novos antibióticos é um importante desafio da investigação em saúde. O potencial farmacológico de cianobactérias tem sido avaliado e descrito, mas, no entanto, ainda não há nenhum composto cianobacteriano que tenha sido aprovado pelas autoridades do medicamento como agente antibacteriano. Neste trabalho avaliámos a atividade de extratos de 40 estirpes de Planktothrix agardhii contra duas bactérias patogénicas: Klebsiella pneumonia e Staphylococus aureus. Para cada espécie bacteriana alvo usou-se uma estirpe de referência (ATCC) e uma estirpe clínica, isolada a partir de amostras de pacientes e estudadas no Laboratório de Resistência aos Antibióticos e Infeções Associadas aos Cuidados de Saúde. As estirpes de P. agardhii foram isoladas de albufeiras portuguesas e têm sido mantidas na coleção “Estela Sousa e Silva Algae Culture Collection” do Laboratório de Biologia e Ecotoxicologia. A biomassa de P. agardhii (200mg) foi extraída com metanol (70%, 10mL/100mg) overnight e sujeita a ciclos de sonicação. O metanol dos extratos foi evaporado e os extratos aquosos resultantes foram purificados em cartuchos C18. A atividade dos extratos contra as bactérias K. pneumonia e S.aureus foi avaliada através do método da Difusão em Disco (EUCAST), usando discos impregnados com 2, 4, 6, 8 e 10 mg de cada extrato. De acordo com os resultados preliminares, nenhum dos extratos apresenta atividade contra K. pneumonia, mas o extrato de P. agardhii LMECYA 256 apresenta um ligeiro halo de inibição relativamente às estirpes de S. aureus, de uma forma aparentemente dependente da dose de extrato aplicada. O S. aureus é uma bacteria Gram-positiva, frequentemente associada a uma vasta gama de patologias, desde simples infeções na pele, até infeções graves como pneumonia e meningite. Assim, revela-se do maior interesse explorar as propriedades antibacterianas de cianobactérias, designadamente do género Planktothrix, contribuindo, desta forma, para um dos desafios atuais da ciência: a identificação de novos antibióticos de origem natural.
- Comparison of saxitoxin-genes expression and production profiles between Aphanizomenon gracile and Cuspidotrix issastchenkoi strains, isolated from freshwater reservoirsPublication . Reis, Marta; Menezes, Carina; Dias, Elsa; Valério, ElisabeteSaxitoxins (STX) are a group of carbamate alkaloids known to inhibit the axons sodium ion channels, thus affecting the nervous system in vertebrates. These neurotoxins cause paralysis and respiratory failure, ultimately ending in death. They are produced by organisms belonging to two different kingdoms: marine eukaryotic dinoflagellates and freshwater prokaryotic cyanobacteria. The unique biosynthetic pathway, which is responsible for encoding proteins that allow synthesizing and exporting STX, is the cluster sxt, already described in several cyanobacterial species. It has been observed that diverse environmental factors affect differently STX production in cyanobacteria. Among those, temperature is the one that aroused greater interest, since it directly affects cyanobacterial growth rates, however controversial results have been reported. Furthermore, studies on the environmental regulation of STX synthesis and transport are quite rare. In this work, we tested the influence of temperature in two STX producers, Aphanizomenon gracile LMECYA40 and Cuspidothrix issatschenkoi LMECYA31, isolated from Portuguese freshwaters and maintained in the ESSACC. Total STX concentration, the expression of genes linked to STX biosynthesis (sxtA) and transport (sxtM and sxtPer) and the percentage of heterocytes per trichome were determined, in four different phases of cyanobacterial growth (lag, early exponential, late exponential and stationary phases). At 20ºC, a higher expression of the sxt genes and higher production of STX in the late exponential and stationary phase was observed in both species. Also, C. issatschenkoi produced more STX throughout the growth cycle than A. gracile. In A. gracile the percentage of heterocytes per trichome was higher in the lag phase, decreasing along the cell cycle. C. issatschenkoi did not form heterocytes throughout the growth cycle. Further experiments are being performed at 10ºC and 30°C in order to understand the effect of temperatures environmentally relevant in STX producers.
- Description of an outbreak of cattle intoxication by cyanobacteria (blue-green algae) in the South of PortugalPublication . Menezes, Carina; Nova, Rita; Vale, Micaela; Azevedo, Joana; Vasconcelos, Vítor; Pinto, CarlosIn 2017, 25 cows from a beef herd consisting of 54 healthy animals, with ages between 1.5 to 4 years old, from Aberdeen Angus breed x Charolais were found dead in Almodôvar, Alentejo, in the South of Portugal. They were grazing on a field of stubble for about 3 weeks when they broke the electric fence that bordered the field and had access to stagnant water from a small stream (Ribeira de Oeiras) that run across the herd. All the animals were seen healthy, by the keeper, until 12 a.m. of Sunday August 27th. When they were last observed before the occurrence, they were resting at the shade of trees and bushes surrounding the Oeiras stream. At this time of the year, this is a normal behaviour due to the high temperatures, and it is common for them to engage in grazing activities in the evening, when the temperature begins to decrease. On the next day (the 28th August), at 7 a.m., the keeper encountered 20 cadavers scattered throughout the land and 5 sick cows. The other 29 animals of the group did not show any clinical signs during the following weeks after the occurrence. In the same period, was reported the death of a heron in the Oeiras stream.
- Environmental biofilms, consequences for health and diseasePublication . Morgado, Patrícia I.; Reis, Lucia; Matias, Rui; Grossinho, Jose; Rebelo, Helena; Rodrigues, Joao; Jordao, LuisaOrnamental waters of easy access and populated with animals are quite attractive and can hide threats to human health. Here we evaluated, during one year, the microbiota of ornamental waters in a Lisbon park in order to assess the risk for human health. A total of 26 different bacterial species were identified during the study. Among these are potential human pathogens such as Aeromonas, E. coli, K. pneumoniae, Pseudomonas and Raoutella. Aeromonas sobria is a resident bacterium whereas other species such as A. hydrophila and A. veronii were sporadically identified. A possible explanation for this result is the presence of a fish population. The presence of E. coli indicates water contamination with fecal materials. We first isolate this bacterium in June when the water temperature increased and then after it was a resident despite the natural temperature drop in the autumn. This might be explained by the replace of the fish population by ducks in October which lead to an increase in water tubirdity and total carbon content. Pseudomonas fluorescens, P. putida and P. oryzihabitans have been considered low-virulence bacteria but recently have been identified as ethiological agents of healthcare assotiated infections (HAI) mostly in immunosupressed individuals. Another recognized HAI agent present is K. pneumoniae. The same bacteria species were isolated from biofilm and water suggesting the existence of an equilibrium between planktonic and biofilm organized bacteria. The role played by biofilm assembly on the emergence of antibiotic resistance is still ongoing for the isolated bacteria, as well as the possible interaction between water chemical composition and bacteria isolates. Potential pathogens (biofilm or planktonic) represent a significant cause of acute bacterial infections mainly in specific populations (paediatric and geriatric). These results support a periodic control of ornamental water microbiota as simple preventive measure to avoid potential health issues.
- Evaluating mcyA gene expression in two toxic cyanobacterial species under different light intensities using RT-qPCRPublication . Salvador, Daniel; Churro, Catarina; Valério, ElisabeteThe aim of this study was assess the influence of light intensity, in the transcription of the mcyA gene and corresponding production of microcystins in Microcystis aeruginosa and Planktothrix agardhii. For that purpose, cultures were exposed to three different light intensities (4, 20 and 30 μmol photons m−2 s−1) for 18 days at 20 ± 1ºC. The growth was followed daily using absorbance readings. At each growth stage samples were collected for cell counting, microcystins quantification by ELISA and RNA extraction. The level of transcripts was quantified by Real-Time RT-qPCR and the relative expression determined using three reference genes, 16S rRNA, gltA and rpoc1.
- Incorporating Sand Dynamics into Beach Water Quality Science and PolicyPublication . Weiskerger, Chelsea; Brandão, JoãoWater quality monitoring and science at nearshore/beach areas is largely limited to microbial/bacterial contamination of water. However, recent research has found that the sand at beaches can be more contaminated than the water itself. Given that most beachgoers spend more time in the sand than the water, they are potentially exposing themselves to higher concentrations of microbes than previously thought. Dynamic exchange of microbes between water and sand has been observed in marine and freshwater systems across the world. Microbes are often deposited from the water, into the sand at the beach during intermediate wave events. When wave energy is high enough, these accumulated microbes can be washed out of the sand and back into the water in a process deemed resuspension. This is in addition to the microbes in the sand that come from humans, wildlife, and waste materials. Within the sand, microbes can move around via spaces between sand grains and may also form biofilms attached to sand grains. When beachgoers play in the sand or the water, they expose themselves to the bacteria contained in it. This may lead to compromised health conditions, including respiratory, gastroenteric, and ear infections. By focusing monitoring and research efforts on water quality at the expense of sand conditions, we may be unintentionally putting beachgoers in danger with our existing protocols. The good news is, researchers are beginning to understand how sand and water interact to form the microbial community at beaches. Collaborative field and numerical modeling studies have characterized the impacts of sand on beach health, and there has been a shift in scientific focus to the entire beach system, or “beachscape”, rather than just the water. The political realm is also beginning to get involved, with discussions of including sand impacts and dynamics in recreational water guidelines currently underway. The issue of recreational water quality is the epitome of a one health challenge – microbial communities are impacted by human and environmental factors, wildlife usage, and even meteorological conditions. These microbial communities can then feed back to the human system by infecting beachgoers from both the water and the sand. In terms of human health, the paramount goal is to minimize the chance of infection in beachgoers, which will lead to increased visitation at beaches as well as social and economic gains for nearshore areas via tourism. By broadening research foci to the entire beachscape, we can better understand what may make the system dangerous to beachgoers, and we can improve beach management for human, economic, and environmental health. A recurring issue in natural resources is the disconnect between research and policy outcomes. The prospective inclusion of sand as a source of microbial contamination at beaches in future beach health guidelines is a concerted and encouraging attempt to bridge that disconnect. Though policy discussions are ongoing, there is promise that research into sand-water interactions will influence human health, environmental health, and policy outcomes as they relate to marine and nearshore systems.
- Intrinsic antibiotic resistance in cyanobacteria: the case of trimethoprimPublication . Dias, Elsa; Manageiro, Vera; Caniça, ManuelaAntibiotic residues poses an increasing concern both at environmental and public health levels. Besides affecting the structure/functioning/diversity of aquatic communities, antibiotic pollution is responsible for one of the most serious threat to the global health: the emergence/dissemination of antibiotic resistance. Cyanobacteria have been recommended as test organisms in the assessment of environmental contaminants such as antibiotics [1]. However, the species sensitivity should be carefully characterized, since cyanobacteria may present intrinsic resistance to some antibiotics, which can seriously compromise the risk assessment results. We have been studied the putative role of cyanobacteria in aquatic resistome and our studies have demonstrated that strains of Microcystis and Planktothrix genus are not susceptible to some antibiotics, namely trimethoprim (up to 1.6 mg/L) [2,3]. In order to understand the cause of the reduced susceptibility of cyanobacteria to several antibiotics, we performed and analyzed the whole genome sequencing of cyanobacteria strains that exhibits a non-susceptible phenotype. Preliminary results revealed that a M. aeruginosa strain possesses the gene that codifies thymidylate synthase (thyX), an alternative enzyme to dihydrofolate redutase (FolA) in the folate metabolism, which is essential for bacteria replication and survival. As the mechanism of action of trimethoprim in bacteria is the inhibition of FolA, our results strongly suggests that the presence of an alternative pathway to FolA may underlie the intrinsic resistance to trimethoprim in cyanobacteria. The identification of intrinsic antibiotic resistance in cyanobacteria is an important tool for identifying which species should not be included as indicator organisms in environmental risk assessment purposes. References: [1] Le Page G, Gunnarsson L, Snape J, Tyler CR (2017) Integrating human and environmental health in antibiotic risk assessment: A critical analysis of protection goals, species sensitivity and antimicrobial resistance. Environm. Int. 109:155–169. [2] Dias E, Oliveira M, Jones-Dias D, Vasconcelos V, Ferreira E, Manageiro V, Caniça M (2015) Assessing the antibiotic susceptibility of freshwater cyanobacteria spp. Front. Microbiol. 6:799. [3] Dias E, Oliveira M, Manageiro V, Vasconcelos V, Caniça M (2019) Deciphering the role of cyanobacteria in water resistome: Hypothesis justifying the antibiotic resistance (phenotype and genotype) in Planktothrix genus. Sci. Total Environm. 20: 447-454.
- Investigating correlation of faecal indicator bacteria and potential pathogenic fungi on Dublin beaches in the interest of public healthPublication . Gitto, Aurora; Stephens, Jayne H.; Brandão, João; Wim, MeijerSandy beaches are usually the preferred location for leisure activities but may pose a risk to public health in particular to children, the elderly and immuno compromised individuals Beach sand and marine water may be a reservoir of opportunistic and pathogenic microbes, as well as faecal indicator bacteria (that influence the bathing water quality status. The growth and the proliferation of microbes in beach sand and water are not restricted to bacteria but include also different groups of fungi such as potentially pathogenic and allergenic moulds, yeasts and dermatophytes Currently, no clear guidance about pathogenic fungi levels in relation to public health is available for these environments.
- Methanol preservation of filamentous cyanobacteria for molecular and morphological studiesPublication . Churro, Catarina; Pereira, Paulo; Vasconcelos, Vitor; Valério, ElisabeteThis study intends to evaluate the application of methanol fixation in the preservation of viable DNA for PCR reactions and also preserve cell morphology for microscopic studies in filamentous cyanobacteria.
- Microbial dynamics and human health risks at the beach – Will climate change matter?Publication . Weiskerger; Brandão, João; Harwood, Valerie JodyBeaches provide recreational opportunities, relief from hot weather, and economic benefits to coastal communities. Visitors to the beach may be exposed to microbial contaminants and pathogens via water, sand, and aerosols. Water and sand coincide at the beach, providing an environment with unique advantages and challenges to pathogen introduction, growth and persistence, transport, and exchange among habitats. Advantages, such as refuge from predators in sand biofilms, and challenges, such as the relatively dry environment, may be both exacerbated and complicated by seasonal variability and predicted long-term anthropogenic climate change. Human exposure to waterborne pathogens will likely be amplified in the face of predicted extreme rain events, warming of water, and sea level rise, combined with urbanization and the popularity of beach activities. Such changes may also alter microbial dynamics at beaches, potentially impacting assumptions and population relationships used in mechanistic water quality and E. coli concentration models as well as quantitative microbial risk assessment frameworks. With model refinement and parameter development designed to fill critical knowledge gaps, predictive models of fecal indicator bacteria and pathogen fate and transport can help to characterize the risk of infectious disease from recreational water use. Here, we not only present a conceptual model that may serve as a first step toward inclusion of biofilm mechanics at beaches, but we also discuss potential approaches to incorporate sand-water interactions into hydrodynamic coastal models for enhanced beach health prediction. While beach health and water quality have long been active areas of research, the sand and sand-water interface habitats at beaches remain relatively unexplored. Recent work has shown that sand can be a reservoir of microbial contaminants at beaches, signaling a potential paradigm shift in both research and management of recreational water and beaches to a more holistic, beachshed-based model, as further detailed in Weiskerger et al. (doi: 10.20944/preprints201901.0225.v1).