21 documents found, page 1 of 3
Evaluation of simultaneous growth of Escherichia coli O157:H7, Salmonella spp.,...
Sousa, José M.; Barbosa, Ana; Araújo, Daniela Eira; Castro, Joana; Azevedo, Nuno Filipe; Cerqueira, Laura; Almeida, Carina Manuela FernandesSeveral multiplex approaches for the simultaneous detection of pathogens in food have been developed in recent years, but the use of a single enrichment medium remains a problem. In this study, six enrichment broths (five non-selective media, tryptic soy broth (TSB), brain heart infusion broth (BHI), buffered peptone water (BPW), universal pre-enrichment broth (UPB), no. 17 broth, and a selective, Salmonella Es...
Using peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) to det...
Oliveira, Ricardo Bruno Costa; Barbosa, Ana; Sousa, Mário; Azevedo, Nuno Filipe; Cerqueira, Laura; Almeida, Carina Manuela FernandesFoodborne diseases have a considerable negative impact on socioeconomic development globally and are an important cause of morbidity and mortality. Among the foodborne bacterial pathogens, Campylobacter spp. is recognized as the leading cause of foodborne illness. Fluorescent in situ hybridization using nucleic acid mimics (NAM-FISH) as probes, in particular peptide nucleic acid (PNA) probes, is a molecular tec...
In vitro selection of DNA aptamers against staphylococcal enterotoxin A
Oliveira, Ricardo; Pinho, Eva; Barros, Maria Margarida; Azevedo, Nuno Filipe; Almeida, Carina Manuela FernandesStaphylococcal enterotoxin A (SEA) is the most frequently reported in staphylococcal food poisoning (SFP) outbreaks. Aptamers are single-stranded nucleic acids that are seen as promising alternatives to antibodies in several areas, including diagnostics. In this work, systematic evolution of ligands by exponential enrichment (SELEX) was used to select DNA aptamers against SEA. The SELEX protocol employed magnet...
Development of an aptamer-based biosensor for the detection of food toxins
Oliveira, Ricardo; Pinho, Eva; Azevedo, Nuno Filipe; Almeida, CarinaAccording to the last EFSA/ECDC report, bacterial toxins are the second leading causative agent (17.0%) of foodborne outbreaks in Europe [1]. Aptasensors, as biosensors that use aptamers are called, are seen as a simple, rapid and cost-effective assay format with high suitability for point-of-care testing, allowing a sensitive and mostly qualitative detection of analytes [2]. In this work, DNA aptamers previous...
Improving aptamer performance with nucleic acid mimics: de novo and post-SELEX ...
Oliveira, Ricardo; Pinho, Eva; Sousa, Ana Luísa; DeStefano, Jeffrey J.; Azevedo, Nuno Filipe; Almeida, CarinaAptamers are structural single-stranded oligonucleotides generated in vitro to bind to a specific target molecule. Aptamers versatility can be enhanced with nucleic acid mimics (NAMs) during or after a selection process, also known as systematic evolution of ligands by exponential enrichment (SELEX). We address advantages and limitations of the technologies used to generate NAM aptamers, especially the applicab...
Development of a novel peptide nucleic acid probe for the detection of Legionel...
Nácher-Vázquez, Montserrat; Barbosa, Ana; Armelim, Inês; Azevedo, Andreia Sofia; Almeida, Gonçalo Nieto; Pizarro, Cristina; Azevedo, Nuno FilipeLegionella are opportunistic intracellular pathogens that are found throughout the environment. The Legionella contamination of water systems represents a serious social problem that can lead to severe diseases, which can manifest as both Pontiac fever and Legionnaires’ disease (LD) infections. Fluorescence in situ hybridization using nucleic acid mimic probes (NAM-FISH) is a powerful and versatile technique fo...
Modelling aptamers with nucleic acid mimics (NAM): from sequence to three-dimen...
Oliveira, Ricardo; Pinho, Eva; Sousa, Ana Luísa; Dias, Oscar; Azevedo, Nuno Filipe; Almeida, Carina Manuela FernandesAptamers are single-stranded oligonucleotides, formerly evolved by Systematic Evolution of Ligands by EXponential enrichment (SELEX), that fold into functional three-dimensional structures. Such conformation is crucial for aptamers ability to bind to a target with high affinity and specificity. Unnatural nucleotides have been used to develop nucleic acid mimic (NAM) aptamers with increased performance, such as ...
Development of a Novel Peptide Nucleic Acid Probe for the Detection of Legionel...
Nácher-Vázquez, Montserrat; Barbosa, Ana; Armelim, Inês; Azevedo, Andreia Sofia; Almeida, Gonçalo Nieto; Pizarro, Cristina; Azevedo, Nuno FilipeLegionella are opportunistic intracellular pathogens that are found throughout the environment. The Legionella contamination of water systems represents a serious social problem that can lead to severe diseases, which can manifest as both Pontiac fever and Legionnaires' disease (LD) infections. Fluorescence in situ hybridization using nucleic acid mimic probes (NAM-FISH) is a powerful and versatile technique fo...
Exploring the antibiotic resistance profile of clinical Klebsiella pneumoniae i...
Oliveira, Ricardo; Castro, Joana; Silva, Sónia Carina; Oliveira, Hugo Alexandre Mendes; Saavedra, Maria José; Azevedo, Nuno Filipe; Almeida, CarinaWhile antibiotic resistance is rising to dangerously high levels, resistance mechanisms are spreading globally among diverse bacterial species. The emergence of antibiotic-resistant Klebsiella pneumoniae, mainly due to the production of antibiotic-inactivating enzymes, is currently responsible for most treatment failures, threatening the effectiveness of classes of antibiotics used for decades. This study asses...
Prevalence of Staphylococcus aureus and staphylococcal enterotoxins in raw milk...
Oliveira, Ricardo; Pinho, Eva; Almeida, Gonçalo; Azevedo, Nuno Filipe; Almeida, Carina Manuela FernandesStaphylococcus aureus and its enterotoxins (SEs) are a serious and costly concern for milk industry and public health [1]. This work aimed to characterize the prevalence of S. aureus and enterotoxins in raw milk collected in the main dairy basin region of Portugal mainland. The presence of S. aureus was confirmed in 53% of refrigerated raw milk samples collected from the bulk tank of 100 dairy farms according t...