Browsing by Author "Oliveira, Ricardo Jorge Dinis"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- An overview of the recent advances in antimicrobial resistancePublication . Oliveira, Manuela; Antunes, Wilson; Mota, Salete; Carvalho, Áurea Madureira; Oliveira, Ricardo Jorge Dinis; Silva,Diana Dias daAntimicrobial resistance (AMR), frequently considered a major global public health threat, requires a comprehensive understanding of its emergence, mechanisms, advances, and implications. AMR’s epidemiological landscape is characterized by its widespread prevalence and constantly evolving patterns, with multidrug-resistant organisms (MDROs) creating new challenges every day. The most common mechanisms underlying AMR (i.e., genetic mutations, horizontal gene transfer, and selective pressure) contribute to the emergence and dissemination of new resistant strains. Therefore, mitigation strategies (e.g., antibiotic stewardship programs—ASPs—and infection prevention and control strategies—IPCs) emphasize the importance of responsible antimicrobial use and surveillance. A One Health approach (i.e., the interconnectedness of human, animal, and environmental health) highlights the necessity for interdisciplinary collaboration and holistic strategies in combating AMR. Advancements in novel therapeutics (e.g., alternative antimicrobial agents and vaccines) offer promising avenues in addressing AMR challenges. Policy interventions at the international and national levels also promote ASPs aiming to regulate antimicrobial use. Despite all of the observed progress, AMR remains a pressing concern, demanding sustained efforts to address emerging threats and promote antimicrobial sustainability. Future research must prioritize innovative approaches and address the complex socioecological dynamics underlying AMR. This manuscript is a comprehensive resource for researchers, policymakers, and healthcare professionals seeking to navigate the complex AMR landscape and develop effective strategies for its mitigation.
- Mapping of key bacterial species for Postmorteminterval calculationPublication . Ferreira, Ana Cláudia; Barbosa, Daniel J.; Campos, Carla; Oliveira, Ricardo Jorge Dinis; Freitas, Ana R.Estimation of the PostmortemInterval (PMI), the time elapsed since death, is one of the most challenging issues in forensic sciences. Most studies focus on extensive bacterial sequencing, but culture-based experiments for higher taxonomic resolution remain scarce. We aimed to analyze total bacterial counts and map Enterococcus faecalis, Staphylococcus aureusand Escherichia coliin different organs and timepoints. Male C57BL/6J SPF mice underwent three independent assays during 11 postmortemtimepoints. Feces and organs (n=10: intestine/stomach/skeletical muscle/liver/spleen/kidney/bladder/lungs/ brain/heart) were collected and resuspended in buffered peptone water, then plated onto enriched nonselective and selective culture media (n=4). Following routine aerobic incubation, Colony Forming Units (CFU) per gram/tissue or per mL/sample were quantified for total/individual bacterial loads. Species were identified by MALDI-TOF MS and statistics were done in GraphPad-Prism v.10.0.1. Species (n=44) from 13 families and 3 phyla were identified, with notable consistency in the presence of Staphylococcus xylosus, E. faecalis, and E. coliacross all experiments. Particular families were consistently identified across all organs, including Enterococcaceae and Enterobacteriaceae mostly in the later stages of decomposition, and Bacillaceae resisting often until the last timepoint, whereas Staphylococcaceae was variably detected. The early and substantial contamination observed in skeletal muscle, stomach, and intestine, makes them unsuitable for PMI calculations. E. faecalisappeared promising as a potential biomarker for kidney, liver, and, possibly, brain invasion at later timepoints, whereas E. faecalisand E. coliin the bladder, and E. coliin the spleen and heart, warrant further investigation for similar biomarker potential. This is one of the first quantitative cultural studies assessing how time elapsing postmortem affects the growth/evolution of key bacterial species, with E. faecalisand E.coliemerging as promising traceable biomarkers in real postmortem contexts. While recognizing the limitations of not considering the complex microbiota network, our pilot study brings an easy species-specific approach and offers a baseline for future human-oriented investigations.
- Optimization of the derivatization procedure for the separation of the stereoisomers of 1,3-dimethylamylamine (1,3-DMAA) by gas chromatography - preliminary dataPublication . Almeida, Maria Mexia de; Silva, Diana Dias da; Oliveira, Ricardo Jorge Dinis; Ribeiro, Cláudia; Dias da Silva, Diana Cristina1,3-Dimethylamylamine (1,3-DMAA),also known as methylhexanamine, is a central nervous system stimulant with structural similarities with amphetamines and therefore presenting over-lapping biological and detrimental effects [1]. Despite being banned, the presence of 1,3-DMAA in dop-ing controls and dietary supplements continues to be of significant concern. This molecule has two stere-ogenic centres and thus four stereoisomers [2]. It is widely recognized that enantiomers may exhibit dif-ferent biological activity, including pharmacokinetics, pharmacodynamics, and toxicity. Consequently, the development of analytical methods for enantioselective separation of 1,3-DMAA is crucial for an accurate determination of the risks associated with each of these stereoisomers. To develop an indirect method by gas chromatography coupled to mass spectrometry (GC-MS) for the separation and identification of the stereoisomers of the 1,3-DMAA. 1,3-DMAA was regenerated with sodium hydroxide, extracted with 0.1% triethylamine in hexane and then derivatized using the enantiomeric pure reagent (R)-(-)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride ((R)-MTPA-Cl). Subsequently, the sample was evaporated, reconstituted in anhydrous ethyl acetate, and analyzed by GC-MS. The chroma-tographic conditions were established using a capillary column containing 5% diphenyl-95% dime-thylpolysiloxane (30 m × 0.25 mm × 0.25 μm), an injector temperature set to 280 ºC, with a temperature ramp starting at 140 ºC and increasing up to 215 ºC at a flow rate of 1 mL/min to a total run of 12.32 min. Results: As preliminary data indicate, the derivatization procedure allowed the formation of 4 diastere-omers of 1,3-DMAA. The chromatographic conditions were optimised, allowing for the separation of the four diastereomers within 12 min. Derivatization and chromatographic conditions were established for enantioselective separation of 1,3-DMAA by GC-MS. Further validation of the method will be crucial for understanding the diastereomers' differential pharmacokinetics and pharmacodynamics, and consequently, the perils associated with their presence in food supplement samples.
- Sequencing technologies in forensic microbiology: current trends and advancementsPublication . Oliveira, Manuela; Dias da Silva, Diana Cristina; Marszałek, Kamila; Kowalski, Michał; Frolova, Alina; Łabaj, Paweł P.; Branicki, Wojciech; Carvalho, Áurea Madureira; Silva, Diana Dias da; Oliveira, Ricardo Jorge DinisForensic microbiology is a subject of interest and research development across the forensic community. Studies of pathogen outbreaks, biocrime or bioterrorism attacks, and analyses of crime scenes fall within this field. Significant progress has been made in evolving DNA sequencing technologies in recent decades. These newly emerged transformative tools have become available to both biomedicine and forensics. Based on the published literature, this review provides an overview of the current trends and developments of NGS (next-generation sequencing) technologies applied to forensic microbiology. These new methods present numerous advantages over traditional sequencing technology and are useful in several practical applications within this forensic field. This article then examines the main challenges and limitations of this technology in forensics, providing a comprehensive review of NGS technology capabilities in expanding the precision and effectiveness of microbial forensic investigations—with the aim of inspiring scientists, forensic experts, lawyers, public health professionals, and policymakers alike to approach this newly powerful sequencing tool appropriately.