Browsing by Author "Jordão, Luisa"
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- Aeromonas spp. in Freshwater Bodies: Antimicrobial Resistance and Biofilm AssemblyPublication . Nascimento, Maria; Rodrigues, João; Matias, Rui; Jordão, LuisaAeromonas spp. are environmental bacteria able to infect animals and humans. Here, we aim to evaluate the role of biofilms in Aeromonas persistence in freshwater. Aeromonas were isolated from water and biofilm samples and identified by Vitek-MS and 16S rRNA sequencing. Antibiotic susceptibility profiles were determined according to EUCAST, and a crystal violet assay was used to assess biofilm assembly. MTT and the enumeration of colony-forming units were used to evaluate biofilm and planktonic Aeromonas susceptibility to chlorination, respectively. Identification at the species level was challenging, suggesting the need to improve the used methodologies. Five different Aeromonas species (A. salmonicida, A. hydrophila, A. media, A. popoffii and A. veronii) were identified from water, and one species was identified from biofilms (A. veronii). A. veronnii and A. salmonicida presented resistance to different antibiotics, whith the highest resistance rate observed for A. salmonicida (multiple antibiotic resistance index of 0.25). Of the 21 isolates, 11 were biofilm producers, and 10 of them were strong biofilm producers (SBPs). The SBPs presented increased tolerance to chlorine disinfection when compared with their planktonic counterparts. In order to elucidate the mechanisms underlying biofilm tolerance to chlorine and support the importance of preventing biofilm assembly in water reservoirs, further research is required.
- Assessing the role played by biofilms on adenoidal surface in a pediatric populationPublication . Rodrigues, João; Reis, Lúcia; Nogueira, Isabel; Duarte, Aida; Subtil, João; Jordão, LuisaAdenoids are a mass of lymphatic tissue located within the nasopharynge. This work aims assessing the relationship between the formation of bacterial biofilms on the adenoid surface and the incidence of infections in the pediatric age.
- Biofilmes de aeromonas sp na água e risco de infeção para o HomemPublication . Meneses, Madalena; Matias, Rui; Rodrigues, Joao; Jordão, Luisaintrodução: As Aeromonas spp. são bactérias oportunistas, responsáveis por infeções no Homem e nos animais. Estas bactérias, frequentemente isoladas do ambiente aquático, possuem diversos fatores de virulência sendo responsáveis pelas infeções intestinais e extraintestinais no ser humano. Os biofilmes são estruturas compostas por microrganismos envolvidos por uma matriz extracelular por eles secretada. No caso dos biofilmes ambientais, existe uma variedade de microrganismos, incluindo, muitas vezes, fungos, microalgas e protozoários. Os biofilmes podem, ou não, estar ligados a superfícies bióticas ou abióticas e diferem, em muitos aspetos, dos seres planctónicos. Em comparação com bactérias isoladas (planctónicas), as que residem em comunidade (biofilme) encontram-se mais protegidas contra vários stresses ambientais. Segundo a literatura, apesar de microrganismos isoladas serem relativamente suscetíveis à desinfeção, populações associadas em biofilmes podem sobreviver a altas doses de cloro.
- Biofilmes do conceito teórico à aplicação práticaPublication . Jordão, LuisaEmbora por facilidade de estudo as bactérias sejam consideradas entidades isoladas, a maioria dos microrganismos persiste em comunidades organizadas denominadas biofilmes. Nesta palestra foram abordados conceitos teóricos de biofilmes e algumas das implicações destes para a saúde dos seres humanos.
- Classic and new approaches to evaluate risk assessment for public health related to exposure to Halogenated Polycyclic Aromatic Hydrocarbons present in ludic watersPublication . Morgado, Patricia I.; Jordão, LuisaRisk assessment for public health related to exposure to Halogenated Polycyclic Aromatic Hydrocarbons present in ludic waters
- Effects of a Changing Earth on Microbial Dynamics and Human Health Risks in the Water/Sand ContinuumPublication . Weiskerger, Chelsea; Brandão, João; Robinson, Clare; Staley, Chris M.; Kleinheinz, Greg; Nshimyimana, Jean Pierre; Kinzelman, Julie; Nevers, Meredith B; Sadowsky, Michael Jay; Phanikumar, Mantha S; Whitman, Richard; Edge, Tom Andrew; Piggot, Alan; Boehm, Alexandria; Aslan, Asli; Badgley, Brian; Heaney, Christopher; Symonds, Erin; Solo-Gabriele, Helena; Fleisher, Jay; Harwood, Jody; Yamahara, Kevan; Vogel, Laura; Jordão, Luisa; Avolio, Lindsay; Merilainen, Paivi; Pitkanen, Tarja; Warish, Ahmed; Staley, Zachery; Klaus, JamesHumans may be exposed to microbial pathogens at recreational beaches via environmental sources such as water and sand. Although infectious disease risk from exposure to waterborne pathogens, and the fecal indicator bacteria (FIB) used to monitor water quality are active areas of research, sand is a relatively unexplored reservoir of pathogens and FIB. Sand and water at beaches experience continuous exchange of microorganisms, and these habitats provide unique advantages and challenges to pathogen introduction, growth, and persistence. Models of FIB and pathogen fate and transport in beach habitats can aid prediction of the risk of infectious disease from recreational water use, but filling knowledge gaps is necessary for accurate modeling. Climate change predictions estimate an increase in global temperatures of 2.5 – 10° F, sea level rise, and intensification of storms and precipitation in some regions. Other global change factors like population growth and urbanization may exacerbate predicted impacts. These changes can alter microbial population dynamics in beach habitats, and may consequently affect the assumptions and relationships used in numerical models. We discuss literature on microbial population and transport dynamics in sand/beach habitats, with an emphasis on how climate change and other anthropogenic influences (e.g., land use, urbanization) should be considered when using and developing models.
- Experiences with evaluation of results from antimicrobial testing on microbial biofilms formed in vitroPublication . Barbora, Gaálová; Černáková, Lucia; Jordão, Luisa; Dohál, Matúš; Bujdáková, HelenaThis presentation summarizes some experiences and troubleshooting leading to the data validation extracted from experiments focused on antimicrobial testing using various antimicrobial agents, surfaces and microorganisms (the yeast Candida albicans, bacteria Streptococcus mutans, Staphylococcus aureus, and Escherichia coli). In screening of anti-biofilm activity when many samples are tested, 3 approaches are fundamental: determination of number of survived cells (CFU), measurement of metabolic activity, and microscopy. These techniques can be combined by different ways, using various substrates or dyes. An evaluation through metabolic activity, the most easy approach, uses spectral measurements at A560 (MTT assay) or A490 (XTT assay). Substrates used in both techniques are associated with activity of dehydrogenases and are reduced in final detected product. Methods are suitable for testing biofilms formed on stable materials (for example, single or dual biofilms formed by C. albicans and S. mutans on hydroxyapatite blocks). However, compounds participating in redox reactions can significantly diminish activity of both substrates. The example of such compound is the photoactive dye methylene blue that is promising compound used in nanotechnology. Similarly, colloidal dispersions containing clay minerals interact with substrates in respect to the charge. In testing of such materials, determination of CFU is the most common choice. Taking into account those limitations, challenging approach is the molecular quantification of live/dead cells in microbial biofilms by real-time PCR. The intercalating dyes ethidium monoazide and propidium monoazide can be selected in respect to microorganisms (for example, S. mutans vs. E. coli). Mentioned methods do not allow describe many details in biofilms. Microscopic techniques in combination with appropriate dyes (CLSM) or nucleotide probes (FISH), but also SEM can help to prove a real fitness and architecture of microbial consortia.
- Exploring the interplay between microplastics and biofilms in freshwaterPublication . Jordão, Luisa; Nogueira, Isabel; Veber, Alexander; Schade, Ulrich; Puskar, LjiljanaPlastic inevitably accumulates in the environment becoming a persistent. In the present work, we aim at documenting MPs occurrence in three collection spots of the biggest European artificial lake over one year period using infrared microscopy. Scanning electron microscopy was used to evaluate MPs colonization by biofilms. PE was the most abundant polymer and biofilms were identified in all plastics.
- Exploring the Potential of Microscopy Techniques to Study Microplastics and Biofilms in Environmental SamplesPublication . José, Silvia; Nogueira, Isabel; Veber, Alexander; Schade, Ulrich; Jordão, LuisaMicro and nanoplastic are found worldwide in aquatic ecosystems ranging from highly populated industrialized areas to the most remote regions of the planet being a hot research topic and a concern. Marine waters have been the major research focus. Despite less studied, freshwaters are of crucial importance since life in general and human beings in particular are highly dependent of freshwater for drinking and food production. This fact shows that freshwater could function as a vehicle for MPs toxicity through all levels of the ecosystem. Although it has been suggested that toxicity is driven not only by the plastic forming units (monomers) but also by adsorbed pollutants (such as PAH, pesticides, PCBs) and associated microorganisms little is known about the underlying mechanisms. The lack of validated protocols for isolation and a gold standard technique to identify micro/nanoplastics are important issues. Infrared microscopy (IRM) with diffraction-limited infrared synchrotron radiation sources adds resolution to the traditional fingerprint IR spectra being a potential candidate to a gold standard technique not only for micro/nanoplastic identification but also for adsorbed pollutants. In the present work, IRM allowed us to identify MPs isolated from freshwater samples. Polyethylene (PE) and polystyrene (PS) were among the most common plastic polymers identified. The colonization of environmental samples of MPs by biofilms was monitored by scanning electron microscopy (SEM). Our data suggests that the presence of biofilms on MPs does not interfere with polymer identification by IRM. Biofilm assembly on MPs by microorganisms isolated from water samples in conditions mimic those found in their natural’s habitats was followed over 3 months. Biofilm biomass was accessed by spectrophotometric methods whereas SEM was used to evaluate biofilm distribution on the MPs particles. The results obtained in vitro correlate with those observed in “real samples”. Biofilms assembled by the microbial consortium used were more abundant on the most common plastics detected in the environmental samples (PE and PS).
- A importância dos biofilmes em otorrinolaringologia pediátricaPublication . Duarte, Aida; Jordão, Luisa; Subtil, JoãoPontos-chave: Saber o que é um biofilme e como a sua estrutura é relevante par os micro-organismos; Saber que é ubiquitário na natureza e no nosso organismo; Reconhecer a sua importância clínica.