Browsing by Author "Silva, N."
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- Acquired antibiotic resistance among wild animals: the case of Iberian Lynx (Lynx pardinus)Publication . Sousa, M.; Gonçalves, A.; Silva, N.; Serra, R.; Alcaide, E.; Zorrilla, I.; Torres, C.; Caniça, Manuela; IgrejaS, G.; Poeta, P.The selective pressure generated by the clinical misuse of antibiotics has been the major driving force leading to the emergence of antibiotic resistance among bacteria. Antibiotics or even resistant bacteria are released into the environment and contaminate the surrounding areas. Human and animal populations in contact with these sources are able to become reservoirs of these resistant organisms. Then, due to the convergence between habitats, the contact of wild animals with other animals, humans, or human sources is now more common and this leads to an increase in the exchange of resistance determinants between their microbiota. Indeed, it seems that wildlife populations living in closer proximity to humans have higher levels of antibiotic resistance. Now, the Iberian Lynx (Lynx pardinus) is a part of this issue, being suggested as natural reservoir of acquired resistant bacteria. The emerging public health concern regarding microbial resistance to antibiotics is becoming true: the bacteria are evolving and are now affecting unintentional hosts.
- Anemia de Fanconi – Estudo retrospetivo num período 34 anosPublication . Ambrósio, A.P.; Silva, N.; Viegas, M.; Silva, M-C.; Ventura, C.; Correia, H.Introdução: A Anemia de Fanconi (AF) é uma doença rara, com uma frequência estimada de 1 a 5 per 1.000.000 de nascimentos, podendo este valor aumentar se for considerado um grupo étnico com consanguinidade. É uma doença autossómica recessiva, que poderá ter uma transmissão ligada ao cromossoma X. Doentes com AF podem apresentar malformações congénitas, falência da medula óssea (que se carateriza por pancitopénia), hipersensibilidade a agentes clastogénicos, fragilidade cromossómica e uma maior suscetibilidade para doenças oncológicas. Devido à grande complexidade desta patologia a primeira abordagem de diagnóstico, consiste na deteção de aberrações cromossómicas (quebras, rearranjos estruturais, radiais, anéis) em células de sangue periférico em cultura com um agente clastogénico como o diepoxibutano (DEB) ou mitomicina C (MMC). Objetivo: Neste trabalho pretende-se apresentar os resultados dos estudos de instabilidade cromossómica induzida por DEB e MMC efetuados na nossa instituição. Métodos: Foi realizada a análise de uma série retrospetiva de 34 anos (1980-2014) de 243 amostras enviadas ao laboratório citogenética com suspeita de AF e de 28 amostras de familiares de doentes com AF. No total, foram analisadas 260 amostras de sangue periférico, 6 de biópsia de pele, 3 de líquido amniótico, 1 de sangue do cordão e 1 de sangue medular. As amostras foram processadas segundo o protocolo estabelecido para a análise cromossómica de doenças associadas a fraturas, incluindo cultura celular com estimulação por MMC e/ou DED, para cada produto biológico, seguida de análise microscópica com determinação da instabilidade cromossómica induzida pelo DEB, de acordo com o protocolo estabelecido pelo International Fanconi Anemia Registry (IFAR). Resultados: Nas 243 amostras analisadas, foram identificados 37 casos com AF. Nos estudos citogenéticos dos familiares com AF foram identificados mais 2 casos positivos para AF. Foram ainda observados, em 4 amostras de suspeita de AF, cariotipos anormais. Conclusão: Neste trabalho foram identificados 39 novos casos com AF, oriundos maioritariamente da região de Lisboa e Vale do Tejo e alguns casos pontuais da região autónoma dos Açores, região centro e dos países africanos de língua oficial portuguesa (PALOP). Este estudo evidência que a maioria dos casos apresentados se encontra subdiagnosticado. Estes resultados não permitem estimar uma frequência de doentes com AF em Portugal, uma vez que não engloba indivíduos de todas as regiões portuguesas, por outro lado estão incluídos dois indivíduos de origem PALOP. É necessário estabelecer um registo nacional de doentes com AF, para se poder calcular a frequência desta patologia no nosso país.
- Are mushrooms a good source of antioxidants for active food packaging?Publication . Silva, N.; Sanches-Silva, A.; Castilho, M.C.; Ramos, F.Active packaging is gaining considerable attention by consumers and food industry due to its unequivocal advantages such as improvement of food quality and extension of food shelf-life. In this frame, active packaging with antioxidant properties is one of the new packaging concepts that comprise greatest developments. Recently, in order to look for sources of natural antioxidants, a vast range of foods and food by-products have been evaluated. The aim of this work was to evaluate the content on phenolics and flavonoids of edible mushrooms of different species and cultivated according to different methods in order to check their potential use in active packaging. The total phenolics content (TPC) and total flavonoids content (TFC) was evaluated.
- First report on MRSA CC398 recovered from wild boars in the north of PortugalPublication . Sousa, M.; Silva, N.; Manageiro, V.; Ramos, S.; Coelho, A.; Gonçalves, D.; Caniça, M.; Torres, C.; Igrejas, G.; Poeta, P.More than 47% of the Portuguese hospital S. aureus isolates are methicillin-resistant (MRSA): one of the highest rates in Europe [1]. Anyhow, MRSA are becoming increasingly prevalent in community-acquired infections and, in recent years, new genetic lineages of MRSA were associated to livestock animals (LA-MRSA) [2, 3]. Nevertheless, less information do exists about the prevalence of MRSA in wild animals but, since 2013, these animals are pointed as natural hosts of MRSA strains [4]. The aim of the present study was to evaluate the antimicrobial resistance in Staphylococcus aureus recovered from wild boars, to analyze their genetic lineages, and to investigate the susceptibility to oxacillin. Samples from mouth and nose of 45 wild boars (Sus scrofa) were collected during hunt activity from November 2012 to January 2013 in the North of Portugal. S. aureus isolates were recovered from 30 of these samples (33%); one isolate/sample was further studied. The susceptibility of the isolates was tested by disk-diffusion test against 14 antimicrobial agents and minimal inhibitory concentration was used to test oxacillin according to EUCAST 2014 guidelines. The genetic lineages of S. aureus were characterized by agr-typing, spa-typing and MLST. From the 30 isolates, 18 S. aureus were susceptible to all antibiotics tested and 7 presented resistance to one or more of the following antibiotics: penicillin (n=3), oxacillin (n=4), cefoxitin (n=1), clindamycin (n=2), gentamicin (n=1), fusidic acid (n=1), ciprofloxacin (n=2), tetracycline (n=1) and linezolid (n=1). One MRSA CC398 (spa-type t899) isolate was detected (oxacillin MIC=32mg/L and mecApositive), which presented resistance to penicillin, tetracycline, and ciprofloxacin and contained the genes of immune evasion cluster (IEC) system (type B). The 29 methicillin-susceptible isolates were typed as ST1 (t1533), ST133 (t3583), ST1643 (t10712), ST2328 (t3750) and the new STs (3220, 3222, 3223, 3224) associated to new spa-types t14311 and t14312. The agr types I, II, III and IV were identified. It is a matter of concern when MRSA and some specific lineages of S. aureus are taken as commensal habitants of the skin and nose of wild animals and are characterized with resistance to various antimicrobial agents in clinical use.
- Influence of agro-industrial by-products on the antioxidant capacity of edible mushroomsPublication . Silva, N.; Sanches-Silva, A.; Castilho, M.C.; Ramos, F.Introduction: Some edible mushrooms have an important antioxidant capacity which can be influenced by the substrate in which they are grown. This work aimed to evaluate the antioxidant capacity of mushrooms commercialized in major supermarket chains of Portugal and to study the influence of the application of agro-industrial byproducts, during the cultivation process, in the antioxidant capacity of mushrooms Pleurotus eryngii, Pleurotus ostreatus and Agrocybe cylindracea. In order to evaluate antioxidant capacity, the ability of capturing electrons by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and inhibition of the β-carotene bleaching were determined by UV-Visible spectrophotometry.
- Prenatal diagnosis of mosaic ring chromosome 16 - a rare event with uncertain prognosisPublication . Brito, F.; M. Silv, M.; Alves, C.; Ferreira, C.; Serafim, S.; Simão, L.; Marques, B.; Pedro, S.; Tarelho, A.; Furtado, J.; Lopes, P.; Silva, N.; Viegas, M.; Fernandes, A.; Teixeira, F.; Gomes, S.; Correia, H.Ring chromosomes are rare cytogenetic findings (prenatal frequency ~ 0.0075%) often associated with an abnormal phenotype, depending of the chromosomal origin, genetic content and the presence of a mosaic. Supernumerary ring chromosome 16 [r(16)] is rarely observed and mosaicism makes the genotype/phenotype correlation difficult. We report a de novo mosaic r(16) detected after prenatal diagnosis in a woman referred for advanced maternal age. Multiplex ligation-dependent probe amplification (MLPA) for aneuploidy testing of chromosomes 13, 18, 21 and X was normal. Karyotype was 47,XX,+r[10]/46,XX[15]. Chromosomal microarray analysis (CMA) on DNA obtained from long-term cultured amniocytes did not detect any alterations. MLPA with a pericentromeric probe kit on an uncultured sample showed a chromosome 16 gain, encompassing 16p11.2 and 16q11.2 regions, including TGFB1I1, AHSP, VPS35 and ORC6 genes, leading to partial characterization of the r(16). Although no phenotype has been correlated with overexpression of these genes, the 16p11.2 region is associated with neurodevelopmental disorders. Nevertheless individuals with microduplication of 16p11.2 and normal development have been described. The lack of a precise definition of genetic content of the r(16) and its mosaic form leads to uncertain prognosis of clinical outcome.
- Staphylococci among Wild European Rabbits from the Azores: A Potential Zoonotic Issue?Publication . Sousa, M.; Silva, V.; Silva, A.; Silva, N.; Ribeiro, J.; Tejedor-Junco, M.T.; Capita, R.; Chenouf, N.S.; Alonso-Calleja, C.; Rodrigues, T.M.; Leitão, M.; Gonçalves, D.; Caniça, M.; Torres, C.; Igrejas, G.; Poeta, P.The prevalence and diversity of Staphylococcus species from wild European rabbits (Oryctolagus cuniculus) in the Azores were investigated, and the antibiotic resistance phenotype and genotype of the isolates were determined. Nasal samples from 77 wild European rabbits from São Jorge and São Miguel islands in Azores were examined. Antibiotic susceptibility of the isolates was determined using the Kirby-Bauer disk diffusion method, and the presence of antimicrobial resistance genes and virulence factors was determined by PCR. The genetic lineages of S. aureus isolates were characterized by spa typing and multilocus sequence typing. A total of 49 staphylococci were obtained from 35 of the 77 wild rabbits. Both coagulase-positive (8.2%) and coagulase-negative (91.8%) staphylococci were detected: 4 S. aureus, 17 S. fleurettii, 13 S. sciuri, 7 S. xylosus, 4 S. epidermidis, and 1 each of S. simulans, S. saprophyticus, S. succinus, and S. equorum. The four S. aureus isolates showed methicillin susceptibility and were characterized as spa type t272/CC121, Panton-Valentine leukocidin negative, and hlB positive. Most of the coagulase-negative staphylococci showed resistance to fusidic acid and beta-lactams, and multidrug resistance was identified especially among S. epidermidis isolates. The mecA gene was detected in 20 isolates of the species S. fleurettii and S. epidermidis, associated with the blaZ gene in one S. epidermidis isolate. Five antimicrobial resistance genes were detected in one S. epidermidis isolate (mecA,dfrA,dfrG,aac6'-aph2'', and ant4). Our results highlight that wild rabbits are reservoirs or "temporary hosts" of Staphylococcus species with zoonotic potential, some of them carrying relevant antimicrobial resistances.