Browsing by Author "Jordão, Luísa"
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- Aplicação dos testes IGRA na deteção de tuberculose latente: o geral e o particularPublication . Rodrigues, J.; Betencourt, C.; João, Inês; Sarioglou, K.; Reis, L.; Cristóvão, P.; Graça, S.; Jordão, Luísa
- Atulhados em plásticosPublication . José, Sílvia; Jordão, LuísaPalestra interativa sobre o percurso e transformação dos plásticos no meio ambiente e na saúde humana: efeitos nefastos nos animais, plantas, solo, água.
- 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.
- Avaliação preliminar da contaminação da água por pireno, formação de derivados de clorados durante o processo de cloração e toxicidade em células HepG2Publication . Silvia, José; Morgado, Patricia I.; Jordão, LuísaOs hidrocarbonetos policíclicos aromáticos (HPAs) são um grupo de contaminantes ambientais, classificados como potencialmente tóxicos, mutagénicos e carcinogénicos, constituindo um problema de saúde pública. No presente estudo, a presença de pireno (Pyr) e 1-cloro-pireno (1-ClPyr) e, diferentes amostras de água (água super ficial, subterrânea e água da rede) foi pesquisada por cromatografia gasosa - espectrometria de massa (GC-MS) após concentração da amostra por micro ex tração em fase sólida. Usando água com diferentes concentrações de Pyr, mostramos que uma concentração mínima deste composto é necessária para que o 1-ClPyr se forme durante o processo de cloração. Finalmente, avaliamos a toxicidade induzida por 1-ClPyr em células HepG2. Os resultados mostraram que este composto é tóxico e afeta a polarização da membrana mitocondrial.
- Bacterial biofilms, antibiotic resistance and healthcare-associated infections: a dangerous connectionPublication . Bandeira, Maria; Carvalho, Patrícia; Duarte, Aida; Jordão, LuísaIn 2012, were estimated 6.7 million cases of healthcare-associated infections (HAI) either in long-term care facilities or acute-care hospitals from which result 37,000 deaths configuring a serious public health problem [1]. The etiological agents are diverse and often resistant to antimicrobial agents. One of the mechanisms responsible for the emergence of drug resistance is biofilm assembly. Biofilms are defined as thin layers of microorganisms adhering to the surface of a structure, which may be organic or inorganic, together with the polymers that they secrete [2]. They are dynamic structures which experience different stages of organization with the ageing and are linked to an increase in bacterial resistance to host defense mechanisms, antibiotics, sterilization procedures other than autoclaving, persistence in water distribution systems and other surfaces. The understanding of bacteria organization within the biofilm and the identification of differences between planktonic and sessile forms of bacteria will be a step forward to fight HAIs. Bacterial isolates were grown in adequate medium. Antibiotic susceptibility was evaluated by broth microdilution method and interpreted according to NCCLS guidelines. A similar assay was performed to evaluate biofilm susceptibility to antibiotics. Bacteria ability to assemble biofilms was assayed by the microtiter-plate test [3] being tested in both abiotic (materials present in healthcare units) and biotic (Hella cells) surfaces. The biofilm structure was assessed by scanning electron microscopy (SEM) in either backscattered electron diffraction or secondary electrons mode. The kinetic of biofilm assembly depends on bacteria growth rate, incubation temperature and medium. Furthermore, the SEM analysis of planktonic and sessile forms of the same bacteria allowed the identification of structural differences which may be involved in virulence (Fig. 1). Bacteria ability to assemble biofilms seems to be independent of the abiotic structure (Fig.2). The same is not observed in biotic surfaces. This fact suggests that biofilm assembly in vivo is dependent of bacteria tropism. The minimum inhibitory concentration (MIC) determine for bacteria organized in biofilms is higher than for their planktonic forms. The increase ranges from 2 to 200 folds and is proportional to the ability of bacteria to assemble biofilms. Further studies will be conducted in order to prevent biofilm assembly within healthcare units which will result in a decrease of HAI and emergence of antibiotic resistant bacteria.
- Bacterial biofilms: a story of persistence and invasionPublication . Sousa, Sara; Bandeira, Maria; Carvalho, Patricia ALmeida; Duarte, Aida; Jordão, LuísaBiofilms are described as colonies of microorganisms that are attached to each other and to a surface, in an irreversible mode. These structures are virtualy everywhere: natural and humanized environments, as well as within living beings (humans and animals). For a long time biofilms where regarded as a bacterial survival strategie. Nowadays, in the industrialized world, the impact of acute bacterial infections caused by rapidly proliferating planktonic cells have gradually decreased in comparison to chronic infections owing to environmental organisms growing as biofilms. The major concern in this field is the healthcare-associated infections (HAIs). In 2012, HAIs estimated cases reached 6.7 million either in long-term care facilities or acute-care hospitals from which result 37,000 deaths configuring a serious public health problem [1]. The etiological agents are diverse being often resistant to antimicrobials and able to assemble biofilms both in abiotic and biotic surfaces. Here we evaluated the ability of different bacteria to assemble biofilms on a model surface and materials mimicking surfaces present either on healthcare units or medical devices. All bacteria were able to assemble biofilmls although following different kinetics and exhibiting different structural features assessed by electron microscopy. Additionally a link was established between bacteria ability to assemble biofilms and increased antibiotic resistance [2]. 1. ECDC Europe; (2012), Annual epidemiological report 2011 2. Bandeira M; (2014), Pathogens (doi:10.3390/pathogens3030720)
- Biofilm formation by ST17 and ST19 strains of Streptococcus agalactiaePublication . Silvestre, Inês; Borrego, Maria José; Jordão, LuísaBacterial biofilms are an important virulence factor with a vital role in evasion from the host immune system, colonization and infection. The aim of the present study was to evaluate in vitro the effects of three environmental factors (H+, glucose and human plasma) in biofilm formation, by carrier and invasive Streptococcus agalactiae strains of ST17 and ST19 sequence types, including DNase producers and non-producers. Bacteria ability to assemble biofilms was classified based on crystal violet assay. Biofilm formation was also monitored by scanning electron microscopy. Depending on the growth medium used, each bacterial isolate could fit in different biofilm production categories. Our data showed that optimal conditions for S. agalactiae biofilm assembly were reached after 48 h incubation at pH 7.6 in the presence of glucose and inactivated human plasma. In the presence of inactivated human plasma, the biofilm biomass of ST19 strains experienced a higher increase than ST17 strains. The composition of the extracellular polymeric matrix of the three strongest biofilm producers (all from ST17) was accessed by enzymatic digestion of mature biofilms and proteins were shown to be the predominant component. The detailed identification of the extracellular protein components should contribute to the development of new therapeutic strategies to fight S. agalactiae infections.
- Biofilm Formation by ST17 and ST19 Strains of Streptococcus agalactiaePublication . Silvestre, Inês; Borrego, Maria José; Jordão, LuísaBacterial biofilms are an important virulence factor with a vital role in evasion from the host immune system, colonization and infection. The aim of the present study was to evaluate in vitro the effects of three environmental factors (H+ , glucose and human plasma) in biofilm formation, by carrier and invasive S. agalactiae strains of ST17 and ST19 sequence types, including DNase producers and nonproducers. Bacteria ability to assemble biofilms was classified based on crystal violet assay. Biofilm formation was also monitored by scanning electron microscopy. Depending on the growth medium used, each bacterial isolate could fit in different biofilm production categories. Our data showed that optimal conditions for S. agalactiae biofilm assembly were reached after 48 h incubation at pH 7.6 in the presence of glucose and inactivated human plasma. In the presence of inactivated human plasma, the biofilm biomass of ST19 strains experienced a higher increase than ST17 strains. The composition of the extracellular polymeric matrix of the three strongest biofilm producers (all from ST17) was accessed by enzymatic digestion of mature biofilms and proteins were shown to be the predominant component. The detailed identification of the extracellular protein components should contribute to the development of new therapeutic strategies to fight S. agalactiae infections.
- Biofilm-forming bacteria on the pharyngeal tonsil in a pediatric populationPublication . Rodrigues, João; Reis, Lucia; Subtil, Joao; Jordão, LuísaObjective: The main goal of this study is to evaluate the existence of a link between biofilm assembly on pharyngeal tonsil and the incidence of recurrent infections within a paediatric population. Methods: Nasal and pharyngeal tonsils scrubs as well as a biopsies of pharyngeal tonsils tissue were collected (n=70) and processed for bacterial identification using standard microbiologic methods. Bacteria were identified at the species level using a VITEC apparatus. Another pharyngeal tonsil biopsies were processed for electron microscopy. Initially, a screening for the presence of biofilms was performed using scanning electron microscopy (SEM) being the positive samples further processed for transmission electron microscopy (TEM). Biofilm assembly assay ability in vitro was evaluated by the microtiter-plate test. The assay was performed at 37ºC in Muller-Hinton broth for different periods of time. Results: As expected a vast number of bacterial species were identified in the samples. The majority were aerobic and a balance between Gram negative and positive bacteria was observed. A good correlation between the floras of the three samples from the same patient was found. The presence of biofilms pharyngeal tonsils was assessed by SEM. The data collected so far suggest that in at least 30% of the samples biofilms were present. In vitro all the microorganisms evaluated were able to assemble biofilms. Conclusion: Biofilm formation can be part of the mechanism involved both in onset and propagation of infections. Further studies must be performed to validate the thesis that pharyngeal tonsils function as a reservoir for microorganisms.
- Biofilmes, micobactérias não tuberculosas e infeçãoPublication . Bandeira, Maria; Wenner, Sigurd; Ferreira, Magda; Carvalho, Patricia Almeida; Jordão, LuísaAs micobactérias não tuberculosas (MNTs) são agentes infeciosos emergentes responsáveis por infeções diversas, nomeadamente infeções associadas aos cuidados de saúde. Neste trabalho foi avaliada a capacidade de formação de biofilmes por duas MNTs (M. smegmatis e M. chelonae). Os biofilmes foram caracterizados utilizando microscopia eletrónica e a eficácia de diversos desinfetantes foi avaliada contra MNTs recuperadas de biofilmes. Os resultados obtidos demonstram que as MNTs são capazes de formar biofilmes em materiais presentes em ambiente hospitalar e de resistir à ação de diversos desinfetantes.