Browsing by Author "Silva, Adriana"
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- Comprehensive typing and genetic analysis of L. monocytogenes isolates: implication for food safety and antibiotic resistance surveillancePublication . Silva, Adriana; Silva, Vanessa; Borges, Vítor; Coelho, Anabela; Batista, Rita; Esteves, Alexandra; Igrejas, Gilberto; Saraiva, Cristina; Gomes, João Paulo; Poeta, PatríciaListeria species are commonly found in various environments and contaminated food, with livestock serving as a significant source of foodborne pathogens. Among these species, Listeria monocytogenes (L. monocytogenes) is particularly noteworthy as it can affect both livestock and humans. Antibiotics are frequently used in food animals for disease treatment and prevention on a large scale. This practice can lead to the selection of antibiotic-resistant bacterial strains, which can then spread to humans through the food chain. Consequently, L. monocytogenes, a ubiquitous foodborne pathogen, has been associated with global outbreaks of foodborne illnesses. To address this concern, the aim of the study was to conduct comprehensive typing and genetic analysis of 13 L. monocytogenes isolates obtained from food and food-processing environments.Among the 13 L. monocytogenes isolates, eight sequence types (ST) were identified: two isolates were identified as belonging to ST9; one as ST155; four as ST3, two as ST121, one as ST8; one as ST87; one as ST1; and one new ST belonging to CC121. Core-genome clustering analysis of L. monocytogenes was made to assess the genetic relatedness among the isolates. The core genome Multilocus Sequence Typing (cgMLST) analysis revealed three genetic clusters of high closely related isolates (≤7 allelic differences (ADs)): cluster 1. Regarding L. monocytogenes typing, ST3 was the most prevalent among the isolates, found in 4 isolates, followed by ST9 and ST121. Some of these isolates, like ST1, ST9 and ST87, were previously associated with human clinical cases. We used Whole Genome Sequencing (WGS) alongside epidemiological data to link strains to human illnesses and potential food sources. Through cgMLST analysis, we identified genetic clusters of closely related isolates, all linked to the same producers. This approach helped us pinpoint common sources of contamination and gain insights into the transmission dynamics of L. monocytogenes in the context of food safety and public health. The escalating antibiotic resistance in Listeria species, particularly in L. monocytogenes, emphasizes the need for heightened surveillance and improved hygiene practices in the food industry to curb the spread of antibiotic resistance and ensure food safety.
- COVID-19 vaccine effectiveness among healthcare workers: a hospital-based cohort studyPublication . Gaio, Vânia; Santos, Ana João; Amaral, Palmira; Faro Viana, João; Antunes, Isabel; Pacheco, Vânia; Paiva, Artur; Pinto Leite, Pedro; Antunes Gonçalves, Lígia; Araújo, Lucília; Silva, Adriana; Matias Dias, Carlos; Kislaya, Irina; Nunes, Baltazar; Machado, AusendaObjectives: Healthcare workers (HCWs) were the first to be prioritised for COVID-19 vaccination. This study aims to estimate the COVID-19 vaccine effectiveness (VE) against SARS-CoV-2 symptomatic infection among HCWs in Portuguese hospitals. Design: Prospective cohort study. Setting and participants: We analysed data from HCWs (all professional categories) from three central hospitals: one in the Lisbon and Tagus Valley region and two in the central region of mainland Portugal, between December 2020 and March 2022. VE against symptomatic SARS-CoV-2 infection was estimated as one minus the confounder adjusted HRs by Cox models considering age group, sex, self-reported chronic disease and occupational exposure to patients diagnosed with COVID-19 as adjustment variables. Results: During the 15 months of follow-up, the 3034 HCWs contributed a total of 3054 person-years at risk, and 581 SARS-CoV-2 events occurred. Most participants were already vaccinated with a booster dose (n=2653, 87%), some are vaccinated with only the primary scheme (n=369, 12.6%) and a few remained unvaccinated (n=12, 0.4%) at the end of the study period. VE against symptomatic infection was 63.6% (95% CI 22.6% to 82.9%) for HCWs vaccinated with two doses and 55.9% (95% CI -1.3% to 80.8%) for HCWs vaccinated with one booster dose. Point estimate VE was higher for individuals with two doses taken between 14 days and 98 days (VE=71.9%; 95% CI 32.3% to 88.3%). Conclusion: This cohort study found a high COVID-19 VE against symptomatic SARS-CoV-2 infection in Portuguese HCWs after vaccination with one booster dose, even after Omicron variant occurrence. The small sample size, the high vaccine coverage, the very low number of unvaccinated individuals and the few events observed during the study period contributed to the low precision of the estimates.
- Efetividade da vacina contra a COVID-19: implementação de estudo de coorte em profissionais de saúde dos hospitais em PortugalPublication . Gaio, Vânia; Silva, Adriana; Amaral, Palmira; Viana, João Faro; Antunes, Isabel; Gonçalves, João; Gonçalves, Lígia A.; Leite, Pedro; Machado, Ausenda; Project Research GroupNum contexto de pandemia, os profissionais de saúde dos hospitais são considerados um grupo de elevado risco para a infeção por SARS-CoV-2 sendo um grupo prioritário para a vacinação. Apesar dos bons resultados da eficácia das vacinas nos ensaios clínicos, são muitos os fatores que podem influenciar a sua eficácia no mundo real (efetividade). Com base num desenho de estudo de coorte prospetivo, desenvolveu-se um projeto cujo objetivo foi avaliar a efetividade da vacina contra a COVID-19 em profissionais de saúde no ambiente hospitalar. Foram recrutados 2367 profissionais de saúde e o seguimento do estudo ocorreu até abril de 2022. A maioria reportou ser enfermeiro (39.8%), do sexo feminino (80,7%) e do grupo etário 40-49 anos (29,5%). Verificou-se ainda que 95,3% dos participantes tinham vacinação completa. Adicionalmente, 3,1% dos profissionais reportou ter tido infeção por SARS-CoV-2 antes da vacinação e 2,8% reportou infeção após vacinação completa. Numa altura em que praticamente toda a população se encontra vacinada contra a COVID-19 é essencial a existência de estudos para o apoio à decisão política na gestão da pandemia e das medidas de saúde pública que possam ser necessárias de implementar.
- First report of linezolid-resistant cfr-positive methicillin-resistant Staphylococcus aureus in humans in PortugalPublication . Silva, Vanessa; Almeida, Francisco; Silva, Adriana; Correia, Susana; Carvalho, José António; Castro, Ana Paula; Ferreira, Eugénia; Manageiro, Vera; Caniça, Manuela; Igrejas, Gilberto; Poeta, PatríciaLinezolid and vancomycin are the most reliable therapeutic agents to treat complicated soft tissue infections caused by multidrug-resistant methicillin-resistant Staphylococcus aureus (MRSA) strains. However, despite the fact that the prevalence of linezolid-resistant MRSA strains (LR-MRSA) remains overall low, in the past few years resistance to linezolid has been reported among human patients worldwide, imposing a public-health concern, in particular when associated with a mobile gene such as cfr [1]. The aim of this study was to identify LR-MRSA isolates recovered from infected diabetic foot ulcers and to characterise their antimicrobial resistance profiles and genetic lineage. (...)
- Listeria monocytogenes from Food Products and Food Associated Environments: Antimicrobial Resistance, Genetic Clustering and Biofilm InsightsPublication . Silva, Adriana; Silva, Vanessa; Gomes, João Paulo; Coelho, Anabela; Batista, Rita; Saraiva, Cristina; Esteves, Alexandra; Martins, Ângela; Contente, Diogo; Diaz-Formoso, Lara; Cintas, Luis M.; Igrejas, Gilberto; Borges, Vítor; Poeta, PatríciaListeria monocytogenes, a foodborne pathogen, exhibits high adaptability to adverse environmental conditions and is common in the food industry, especially in ready-to-eat foods. L. monocytogenes strains pose food safety challenges due to their ability to form biofilms, increased resistance to disinfectants, and long-term persistence in the environment. The aim of this study was to evaluate the presence and genetic diversity of L. monocytogenes in food and related environmental products collected from 2014 to 2022 and assess antibiotic susceptibility and biofilm formation abilities. L. monocytogenes was identified in 13 out of the 227 (6%) of samples, 7 from food products (meat preparation, cheeses, and raw milk) and 6 from food-processing environments (slaughterhouse-floor and catering establishments). All isolates exhibited high biofilm-forming capacity and antibiotic susceptibility testing showed resistance to several classes of antibiotics, especially trimethoprim-sulfamethoxazole and erythromycin. Genotyping and core-genome clustering identified eight sequence types and a cluster of three very closely related ST3 isolates (all from food), suggesting a common contamination source. Whole-genome sequencing (WGS) analysis revealed resistance genes conferring resistance to fosfomycin (fosX), lincosamides (lin), fluoroquinolones (norB), and tetracycline (tetM). In addition, the qacJ gene was also detected, conferring resistance to disinfecting agents and antiseptics. Virulence gene profiling revealed the presence of 92 associated genes associated with pathogenicity, adherence, and persistence. These findings underscore the presence of L. monocytogenes strains in food products and food-associated environments, demonstrating a high virulence of these strains associated with resistance genes to antibiotics, but also to disinfectants and antiseptics. Moreover, they emphasize the need for continuous surveillance, effective risk assessment, and rigorous control measures to minimize the public health risks associated to severe infections, particularly listeriosis outbreaks. A better understanding of the complex dynamics of pathogens in food products and their associated environments can help improve overall food safety and develop more effective strategies to prevent severe health consequences and economic losses.
- Resistome, Virulome, and Clonal Variation in Methicillin-Resistant (MRSA) in Healthy Swine Populations: A Cross-Sectional StudyPublication . Silva, Vanessa; Silva, Adriana; Barbero, Raquel; Romero, Mario; Del Campo, Rosa; Caniça, Manuela; Cordeiro, Rui; Igrejas, Gilberto; Poeta, PatriciaThis cross-sectional study investigates the methicillin-resistant (MRSA): its prevalence, antimicrobial resistance, and molecular characteristics in healthy swine populations in central Portugal. A total of 213 samples were collected from pigs on twelve farms, and MRSA prevalence was assessed using selective agar plates and confirmed via molecular methods. Antimicrobial susceptibility testing and whole genome sequencing (WGS) were performed to characterize resistance profiles and genetic determinants. Among the 107 MRSA-positive samples (83.1% prevalence), fattening pigs and breeding sows exhibited notably high carriage rates. The genome of 20 isolates revealed the predominance of the ST398 clonal complex, with diverse types identified. Antimicrobial susceptibility testing demonstrated resistance to multiple antimicrobial agents, including penicillin, cefoxitin, and tetracycline. WGS analysis identified a diverse array of resistance genes, highlighting the genetic basis of antimicrobial resistance. Moreover, virulence gene profiling revealed the presence of genes associated with pathogenicity. These findings underscore the significant prevalence of MRSA in swine populations and emphasize the need for enhanced surveillance and control measures to mitigate zoonotic transmission risks. Implementation of prudent antimicrobial use practices and targeted intervention strategies is essential to reducing MRSA prevalence and safeguarding public health. Continued research efforts are warranted to elucidate transmission dynamics and virulence potential, ultimately ensuring food safety and public health protection.
- Unveiling Antibiotic Resistance, Clonal Diversity, and Biofilm Formation in Isolated from Healthy Swine in PortugalPublication . Silva, Adriana; Silva, Vanessa; Dapkevicius, Maria de Lurdes Enes; Azevedo, Mónica; Cordeiro, Rui; Pereira, José Eduardo; Valentão, Patrícia; Falco, Virgílio; Igrejas, Gilberto; Caniça, Manuela; Poeta, PatríciaEscherichia coli, a commensal microorganism found in the gastrointestinal tract of human and animal hosts, plays a central role in agriculture and public health. Global demand for animal products has promoted increased pig farming, leading to growing concerns about the prevalence of antibiotic-resistant E. coli strains in swine populations. It should be noted that a significant portion of antibiotics deployed in swine management belong to the critically important antibiotics (CIA) class, which should be reserved for human therapeutic applications. This study aimed to characterize the prevalence of antibiotic resistance, genetic diversity, virulence characteristics, and biofilm formation of E. coli strains in healthy pigs from various farms across central Portugal. Our study revealed high levels of antibiotic resistance, with resistance to tetracycline, ampicillin, tobramycin, and trimethoprim-sulfamethoxazole. Multidrug resistance is widespread, with some strains resistant to seven different antibiotics. The ampC gene, responsible for broad-spectrum resistance to cephalosporins and ampicillin, was widespread, as were genes associated with resistance to sulfonamide and beta-lactam antibiotics. The presence of high-risk clones, such as ST10, ST101, and ST48, are a concern due to their increased virulence and multidrug resistance profiles. Regarding biofilm formation, it was observed that biofilm-forming capacity varied significantly across different compartments within pig farming environments. In conclusion, our study highlights the urgent need for surveillance and implementation of antibiotic management measures in the swine sector. These measures are essential to protect public health, ensure animal welfare, and support the swine industry in the face of the growing global demand for animal products.
- Vaccine effectiveness against symptomatic SARS-CoV-2 infection in adults aged 65 years and older in primary care: I-MOVE-COVID-19 project, Europe, December 2020 to May 2021Publication . Kissling, Esther; Hooiveld, Mariette; Sandonis Martín, Virginia; Martínez-Baz, Iván; William, Naoma; Vilcu, Ana-Maria; Mazagatos, Clara; Domegan, Lisa; de Lusignan, Simon; Meijer, Adam; Machado, Ausenda; Brytting, Mia; Casado, Itziar; Murray, Josephine-L.K.; Belhillil, Sylvie; Larrauri, Amparo; O’Donnell, Joan; Tsang, Ruby; de Lange, Marit; Rodrigues, Ana Paula; Riess, Maximilian; Castilla, Jesús; Hamilton, Mark; Falchi, Alessandra; Pozo, Francisco; Dunford, Linda; Cogdale, Jade; Jansen, Tessa; Guiomar, Raquel; Enkirch, Theresa; Burgui, Cristina; Sigerson, Debbie; Blanchon, Thierry; Martínez Ochoa, Eva María; Connell, Jeff; Ellis, Joanna; van Gageldonk-Lafeber, Rianne; Kislaya, Irina; Rose, Angela M.C.; Gomez, Verónica; Nunes, Baltazar; Roquette, Rita; Silva, Adriana; Melo, Aryse; Costa, Inês; Verdasca, Nuno; Conde, Patrícia; Valenciano, Marta; I-MOVE-COVID-19 primary care study teamThe I-MOVE-COVID-19 network collates epidemiological and clinical information on patients with coronavirus disease (COVID-19), including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virological characterisation in 11 European countries [1]. One component of I-MOVE-COVID-19 is the multicentre vaccine effectiveness (VE) study at primary care/outpatient level in nine European study sites in eight countries. We measured overall and product-specific COVID-19 VE against symptomatic SARS-CoV-2 infection among those aged 65 years and older. We also measured VE by time since vaccination.