Browsing by Author "Rodrigues, João"
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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.
- 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.
- Aetiology of Acute Gastroenteritis in Hospitalized Children from Lisbon AreaPublication . Costa, Inês; Júlio, Cláudia; Rodrigues, João; Machado, Jorge; Correia, Cristina; Oliveira, Maria Marisa; Escobar, Carlos; Costa, Beatriz; Brito, Maria João; Correia, Paula; Ferreira, Gonçalo Cordeiro; Simões, Maria João; Oleastro, MónicaGastroenteritis is a major cause of morbidity and mortality worlwide. Aim: Determine the etiology of gastroenteritis in a cohort of children hospitalized Methods: From May 2011 to January 2012, stool samples were collected from children (4.2 ± 4.8 years). Viral agents (enteric and enterovirus) were detected by RT-PCR. Stool specimens were also tested for bacteria and parasites, by conventional methods. Results: From the 82 stool samples, 42(51.2%) were positive for virus, 22 (26.8%) for bacteria and 35.6% (26/73) for parasites. An association between viral infection and age<3 years (OR=4.92, p<0.01) was observed. Distribution of viral agents was NorovirusII (33.3%), Enterovirus (31%), Rotavirus (23.8%), Adenovirus (9.5%), NorovirusI (2.4%). Simultaneous detection of two viral agents was observed in seven cases (16.7%) - NorovirusII and Enterovirus was the most frequent (57.1%); association with another agent was detected in 33.3% samples. Eight of 22 samples (36.4%) were positive for Campylobacter jejuni, 5 (22.7%) for Salmonella spp, 7 (31.8%) for E. coli, although always in co-infection with another agent, and 1 (4.5%) for Shigella spp. 38.5% of the samples were positive for Cryptosporidium spp., 23.1% for Giardia sp. and 3.8% for Entamoeba histolytica. 69.2% of the parasites were co-detected with other agents. Conclusion: Results suggest that viral agents are the most common among children with acute gastroenteritis, although co-infections with bacteria and parasites are frequent. The most common viral agent associated with acute diarrhea was NorovirusII. An important percentage of cases with no infectious aetiology identified, suggesting that other emergent agents are probably implicated.
- Antimicrobial Resistance and Biofilms Underlying Catheter-Related Bloodstream Coinfection by Enterobacter cloacae Complex and Candida parapsilosisPublication . Štefánek, Matúš; Wenner, Sigurd; Borges, Vítor; Pinto, Miguel; Gomes, João Paulo; Rodrigues, João; Faria, Isabel; Pessanha, Maria Ana; Martins, Filomena; Sabino, Raquel; Veríssimo, Cristina; Nogueira, Isabel D.; Carvalho, Patrícia Almeida; Bujdáková, Helena; Jordao, LuisaBiofilm-associated infections are a public health concern especially in the context of healthcare-associated infections such as catheter-related bloodstream infections (CRBSIs). We evaluated the biofilm formation and antimicrobials resistance (AMR) of Enterobacter cloacae complex and Candida parapsilosis co-isolated from a CRBSI patient. Antimicrobial susceptibility of central venous catheters (CVCs) and hemoculture (HC) isolates was evaluated, including whole genome sequencing (WGS) resistome analysis and evaluation of gene expression to obtain insight into their AMR determinants. Crystal violet assay was used to assess dual biofilm biomass and microscopy was used to elucidate a microorganism’s distribution within biofilms assembled on different materials. Bacteria were multidrug-resistant including resistance to colistin and beta-lactams, likely linked to the mcr-9-like phosphoethanolamine transferase and to an ACT family cephalosporin-hydrolyzing class C beta-lactamase, respectively. The R398I and Y132F mutations in the ERG11 gene and its differential expression might account for C. parapsilosis resistance to fluconazole. The phenotype of dual biofilms assembled on glass, polystyrene and polyurethane depends on the material and how biofilms were initiated by one or both pathogens. Biofilms assembled on polyurethane were denser and richer in the extracellular polymeric matrix, and microorganisms were differently distributed on the inner/outer surface of the CVC.
- 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.
- 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.
- Biofilms within the human body and its clinical implicationsPublication . Jordão, Luísa; Subtil, João; Lavado, Paula; Rodrigues, João; Reis, Lúcia; Faria, Isabel; Pessanha, Maria AnaBiofilms with medical implications could be find on medical devices or on organs. Here we discuss the results obtained in two studies one associated with an organ (adenoid) and another associated with a medical device (central venous catheters- CVC). In the first study, we evaluate the association between biofilm assembly on adenoids and the incidence of recurrent infections in a paediatric population comparing adenoid samples from adenoidectomy groups with and without infectious indication. Biofilms were present in 27.4% of the adenoid samples. For H. influenzae, S. aureus, S. pyogenes, S. pneumococcus and M. catarrhalis, no association was found between ability to assemble biofilms in vitro and the presence of biofilms on adenoids, and the same was found for antibiotic resistance. The most isolated bacterium was H. influenzae that revealed after further characterization to be non-typeable (NT). No statistical difference was found on biofilm presence between the two groups, infectious versus non-infectious diagnosis. The same was true for biofilm assembling ability of bacteria found on adenoid surface and core. As in other studies, we did not find a correlation between biofilm formation and susceptibility or resistance to antibiotics and this raise the question of the importance of biofilms on the pathogenesis of infectious diseases. In the second study, we explore the relation between the presence of biofilms on central venous catheters and central venous catheter-related bloodstream infection (CRBSI). Our preliminary results (relative to data collected over 10 months) show that Staphylococci, either coagulase negative or positive, are major etiologic agents of this healthcare associated infection.
- 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.
- Caracterização molecular e suscetibilidade aos antimicrobianos de isolados de L. monocytogenes na região de LVT em 2015Publication . Silveira, Leonor; Pista, Ângela; Maia, Carla; Barreira, Maria João; Rodrigues, João; Reis, Lúcia; Machado, JorgeCaracterização molecular e suscetibilidade aos antimicrobianos de isolados de L. monocytogenes na região de LVT em 2015.
- Caraterização molecular e suscetibilidade aos antimicrobianos de isolados clínicos de Listeria monocytogenes na região de Lisboa e Vale do Tejo em 2015Publication . Silveira, Leonor; Pista, Ângela; Maia, Carla; Barreira, Maria João; Rodrigues, João; Reis, Lúcia; Machado, JorgeListeria monocytogenes é o agente causal da listeriose, uma doença grave considerada de vigilância prioritária a nível europeu, com taxas de hospitalização (98,9%) e de letalidade (15,0%) elevadas. Este estudo teve como objetivo a caraterização das estirpes de L. monocytogenes recebidas no Instituto Nacional de Saúde Doutor Ricardo Jorge em 2015. A serotipagem foi realizada por PCR multiplex, a tipagem por PFGE e também foi estudada a suscetibilidade aos antimicrobianos. O serotipo mais comum foi IVb (85,7%). A maioria das estirpes é sensível aos antimicrobianos em apreciação, com exceção de uma estirpe que apresentou resistência ao meropenemo e outra que apresentou resistência à eritromicina e ao trimetoprim/sulfametoxazol. Existe uma grande heterogeneidade de perfis de PFGE entre os isolados estudados, tendo sido detetados alguns clusters. A utilização de sequenciação de genoma completo para caraterização de estirpes, nomeadamente de L. monocytogenes está a ganhar terreno a nível mundial, vindo substituir as técnicas goldstandard. A sua aplicação no Laboratório Nacional de Referência de Infeções Gastrintestinais permitiu em 2015 a confirmação laboratorial de um surto.
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