Browsing by Author "Nogueira, Isabel"
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- Adenoids, friends or foes?Publication . Subtil, João; Lavado, Paula; Rodrigues, João; Rodrigues, Lúcia; Nogueira, Isabel; Duarte, Aida; Jordao, LuisaThe main goal of this study is to evaluate the existence of a link between biofilm assembly on adenoids and the incidence of recurrent infections within a paediatric population. Thirty-three different bacterial genera were isolated from 186 samples (nasal/adenoid scrubs and adenoid biopsies) being Haemophilus, Neisseria, Streptococcus and Staphylococcus the most frequent. Biofilms were present in 27.4% of the adenoid samples as assessed by SEM. Since the aim of the study is to assess the role of biofilms on adenoid colonization/ invasion and onset of infection a group of samples harbouring clinically relevant bacteria (H.influenzae, S. aureus, S. pyogenes, S. pneumococcus and Moraxella) both on the adenoid surface and core were selected for further studies. Based on biofilm assembly in vitro, assessed by crystal violet assay, bacteria were classified as weak, moderate and strong biofilm assemblers. No direct relation between the ability to assemble biofilms in vitro and the presence of biofilms on the adenoid (biofilm in vivo) was found. A similar result was obtained for antibiotic susceptibility with the majority of bacteria being antibiotic susceptible independently of its origin (sample with or without biofilms). This result might be explained at least partially, by the nature of the sample since the adenoidectomy can only be performed in individuals without infection. H. influenzae, the most isolated bacterium, is an opportunistic pathogen, highly adapted to colonize the upper respiratory tract and easily progresses to infection, especially in children. For this reason, virulence factors such as the capsular type were investigated by PCR. However, all strains were characterized as non-capsulated, which might explain adenoid colonization and biofilm formation, as have been also described in the literature. Further studies must be performed to validate the thesis that adenoids function as a reservoir of etiologic agents of respiratory and ear infections.
- 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.
- Avaliação do risco para a saúde pública resultante do contacto com águas recreativas e ornamentaisPublication . Fernandes, Vera; Paulino, Sérgio; Costa, Clélia; Rodrigues, João Carlos; Reis, Lúcia; Nogueira, Isabel; Carvalho, Patricia; Duarte, Aida; Jordão, LuísaObjetivos: Este trabalho teve como objetivo caraterizar a população de microrganismos presente em águas recreativas (piscinas) e ornamentais (lagos), bem como avaliar o risco para a saúde pública do contacto com as mesmas.
- Biofilms and catheter related bloodstream infection: a tale of two kigdomsPublication . Borges, Vítor; Wenner, Sigurd; Nogueira, Isabel; Faria, Isabel; Pessanha, Maria Ana; Verissimo, Cristina; Sabino, Raquel; Rodrigues, Joao; Matias, Rui; Martins, Filomena; Carvalho, Patricia; Gomes, Joao Paulo; Jordão, LuísaBackground: Biofilm-associated infections are a public health concern in the context of healthcare-associated infections (HAI) such as catheter-related bloodstream infections (CRBSI). Here, we studied two top ten CRBS etiological agents, Enterobacter cloacae and Candida parapsilosis, isolated from a patient with CRBSI in order to understand the role played by biofilms on this HAI. Materials/methods: E.cloacae and C.parapsilosis were isolated from CVC and peripheral blood by standard procedures. EUCAST guidelines were followed for antimicrobial susceptibility evaluation. Single and/or mixed biofilms were assembled on different materials in Mueller-Hinton broth with 2% glucose. Biofilm assembly was assessed by crystal violet assay and scanning electron microscopy (SEM). Fluorescence in situ hybridization (FISH) was used for identification and to assess microorganisms distribution within the biofilm (3D reconstruction). In addition, Focus Ion Beam (FIB)-SEM was used to assess biofilms assembled on inner and outer surfaces of CVCs and construct tomograms. CVC and hemoculture (HC) isolates were subjected to whole-genome sequencing (WGS). Results: All Enterobacter and Candida isolates were antimicrobial resistant. Of note, E. cloacae-CVC revealed an additional resistance (ceftolozame-tazobactam) in comparison to the HC- isolate. Both microorganisms assembled biofilms on glass, polystyrene and polyurethane. Mixed biofilms were denser when both microorganisms were present from the beginning. Biofilm phenotype was not dependent of biofilm initiation by E.cloacae or C.parapsilosis. FISH and SEM analysis showed that biofilm bottom layer was in all cases richer in E.cloacae. Environmental isolates of the same species were also tested, showing that this biofilm phenotype is not a general feature. Using polyurethane catheters (shape/material factor), we observed denser mixed biofilms richer in EPS. FIB-SEM preliminary results suggest that biofilms assembled on inner and outer catheter surface might differ on microorganisms’ distribution. WGS confirmed the genetic identity of the CVC/HC pairs while corroborating the virulence potential and antimicrobial resistant character of the CRBSI-driving pathogens. Conclusions: The results suggest that biofilms allow interaction and adaptation of microorganisms belonging to different kingdoms (Bacteria and Fungi). Adaptation might affect virulence in a transitory or permanent fashion, with potential impact on microorganisms’ potential to cause CRBSI.
- Caracterização da população bacteriana em barragens na bacia hidrográfica do SadoPublication . Sousa, Maria; Morgado, Patrícia; Rodrigues, João; Matias, Rui; Nogueira, Isabel; Jordão, LuísaAs barragens são fundamentais para a gestão dos recursos hídricos. Estas infraestruturas permitem regular os caudais e aproveitar a água para diversas atividades como a agricultura, pecuária, captação para consumo humano e turismo (p.e. praias fluviais e despor tos aquáticos). Neste estudo, foi avaliada a flora bacteriana (planctónica e organizada em biofilmes) presente em 4 barragens da bacia hidrográfica do rio Sado. A caracterização da flora bacteriana presente para além de permitir a caracterização do ecossistema permite inferir sobre potenciais riscos para a saúde humana decorrentes dos diversos usos da água.
- 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).
- Magnetite nanoparticles functionalized propolis extract as nano-antibiotics against methicillin resistant strains of Staphylococcus aureusPublication . El-Guendouz, Soukaina; Lyoussi, Badiaa; Lourenço, João P.; Rosa Costa, Ana M.; Miguel, Maria G.; Dias, Cristina M.B.; Manhita, Ana C.; Luísa, Jordão; Nogueira, Isabel; Faleiro, Maria LeonorDue to their ability to penetrate planktonic and biofilm organized bacteria , nano-antimicrobial agents have been perceived, in recent years, in almost every domain of life especially in health care for the control of infectious diseases. Magnetite nanoparticles (MNPs) have been evaluated for inhibiting microbial growth and biofilm formation. The aim of this study was to evaluate the effect of Moroccan propolis extract functionalized magnetite nanoparticles as nanoantibiotics against methicillin resistant Staphylococcus aureus (MRSA) growth. Chemical composition of propolis was established by pyrolysis GC-MS method. The fabricated nanostructure was characterized by X-ray Diffraction, Transmission Electron Microscopy, and Fourier Transform-Infrared Spectroscopy. FTIR spectroscopy data allowed to confirm functionalization of the MNPs upon contact with oleic acid (OA). Further functionalization with either propolis extract or chloramphenicol was also confirmed by observation of the corresponding FTIR spectra. When both components were added together to OA-functionalized MNPs, the presence of the former is clear whereas that of the latter is less evident, although possible. The use of MNPs functionalized with propolis and chloramphenicol (positive control) at MIC value against methicillin susceptible S. aureus (MSSA) and MRSA strains inhibited the bacterial growth. After the treatment with functionalized MNPs the cells showed disruption of the cell wall as assessed by transmission electron microscopy (TEM). The use of the combination of propolis and the chloramphenicol antibiotic in free form at minimum inhibitory concentration largely impaired both MSSA and MRSA strains, after 2 h of treatment no viable cells of MRSA 2 and MRSA 16 were recovered.
- Magnetite nanoparticles functionalized with propolis against methicillin resistant strains of Staphylococcus aureusPublication . El-Guendouz, Soukaina; Lyoussi, Badiaa; Lourenço, João P.; Rosa da Costa, Ana M.; Miguel, Maria G.; Barrocas Dias, Cristina; Manhita, Ana; Jordao, Luisa; Nogueira, Isabel; Faleiro, Maria L.Magnetite nanoparticles (MNPs) have been evaluated for inhibiting microbial growth and biofilm for- mation. In this study the effect of the nanocomposite Moroccan propolis extract / MNPs acting against methicillin resistant strains of Staphylococcus aureus (MRSA) was evaluated. Chemical composition of propolis was established by pyrolysis coupled to gas chromatography and mass spectrometry method (pyrolysis GC/MS). MNPs were obtained through the co-precipitation method. The fabricated nanostruc- ture was characterized by X-ray Diffraction (DRX), Transmission Electron Microscopy (TEM), and Fourier Transform-Infrared Spectroscopy (FTIR). TEM of MNPs provided a particle average size of 15 nm, FTIR spectral analysis enabled a fast way of identification of MNPs, attesting the occurrence of the different combinations. The use of MNPs loaded with propolis and the antibiotic chloramphenicol at Minimum Inhibitory Concentration (MIC) value inhib- ited the bacterial growth of MSSA (methicillin susceptible strain of S. aureus ) and MRSA strains. After the treatment with MNPs-OA-P-CLo nanocomposite (MNPs with oleic acid, propolis and chloramphenicol), the disruption of the bacterial cell was observed by TEM. The combination of propolis and chlorampheni- col in free form at MIC value largely impaired both MSSA and MRSA strains as, after 2 h of treatment, no viable cells of MRSA 2 and MRSA 16 were recovered. Hence, the results elucidated a new antibac- terial nanocomposite synthesis, for possible applications as prospective nanoantibacterial agents or drug carriers.
- Occurence of persistent environmental pollutants in freshwaterPublication . Jordão, Luisa; Mansilha, Catarina; Melo, Armindo; Nogueira, Isabel; Veber, Alexander; Puskar, Ljiljana; Schade, UlrichFreshwater pollution is a huge concern. Occurence of 2 groups of persistent pollutants with similar chemical properties (polycyclic aromatic hydrocarbons and microplastics) in Alqueva’s surface water were evaluated during 2021. Samples were collected, once per season, at 3 spots related to touristic activities. Biofilm presence on plastic and natural materials was monitored and compared.