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      2
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    Copper-Modified Cellulose Paper: A Comparative Study of How Antimicrobial Activity Is Affected by Particle Size and Testing Standards
    (MDPI AG, 2025-01-08)
    Sara Ramírez
    ;
    Fabian Zúñiga
    ;
    Alejandra Amenábar
    ;
    CONTRERAS CORREA, PAULINA DEL PILAR  
    ;
    Viviana Benavides
    This study aims to provide evidence that when testing cellulose paper modified with copper particles (CuPs), the particle size and the analysis method influence the antimicrobial activity observed by this material. Commercial CuPs of nanometric size (2.7 nm, CuNPs) and micrometric size (2.5 µm, CuMPs) were used to modify cellulose paper sheets. CuPs were incorporated during the pulp disintegration phase (stage 1) of the sheet formation process, according to the ISO 5269-1:2005 standard. Modified paper sheets retained 16% and 14% of CuNPs and CuMPs, respectively. Additionally, CuPs were distributed randomly on the fiber surfaces, often forming aggregates. Finally, the antimicrobial activity of the modified paper sheets was evaluated using ISO 20645:2004 and ISO 20743:2013. The results showed that the antimicrobial activity assessed using each standard method is conditioned by the mechanism of action of the CuPs and, therefore, by their size. It was concluded that ISO 20645:2004 is suitable for evaluating the antibacterial effect of paper/CuNPs, as nanoparticles diffuse from the paper and are released into the culture medium. In contrast, ISO 20743:2013 can be used for both CuNP- and CuMP-based paper, as it evaluates the antibacterial effect based on the direct interaction between the copper particle and the bacteria.
    Scopus© Citations 2  14
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    Excess burden of antibiotic-resistant bloodstream infections: evidence from a multicentre retrospective cohort study in Chile, 2018–2022
    (2024)
    Kasim Allel
    ;
    Anne Peters
    ;
    Hassan Haghparast-Bidgoli
    ;
    Maria Spencer-Sandino
    ;
    Jose Conejeros
    Scopus© Citations 2  4
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    Dissecting the Mechanisms of Linezolid Resistance in a Drosophila melanogaster Infection Model of Staphylococcus aureus
    (2013)
    Lorena Diaz
    ;
    Dimitrios P. Kontoyiannis
    ;
    Diana Panesso
    ;
    Nathaniel D. Albert
    ;
    Kavindra V. Singh
    Scopus© Citations 12  2
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    Piomiositis en niños: Reporte de 2 casos
    (2013)
    Felipe Cavagnaro
    ;
    Jaime Rodríguez
    ;
    M. Eugenia Arancibia
    ;
    Bárbara Walker
    ;
    Aníbal Espinoza
      3Scopus© Citations 3
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      7Scopus© Citations 16
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    Dynamics of the MRSA Population in a Chilean Hospital: a Phylogenomic Analysis (2000–2016)
    (2023)
    José R. W. Martínez
    ;
    Paul J. Planet
    ;
    Maria Spencer-Sandino
    ;
    RIVAS JIMENEZ, LINA MARIA  
    ;
    Ahmed M. Moustafa
    <jats:p> Methicillin-resistant <jats:named-content content-type="genus-species">Staphylococcus aureus</jats:named-content> (MRSA) is a major public health pathogen that disseminates through the emergence of successful dominant clones in specific geographic regions. Knowledge of the dissemination and molecular epidemiology of MRSA in Latin America is scarce and is largely based on small studies or more limited typing techniques that lack the resolution to represent an accurate description of the genomic landscape. </jats:p>
    Scopus© Citations 6  4
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    Type I collagen hydrogels as a delivery matrix for royal jelly derived extracellular vesicles
    (2020)
    Orlando J. Ramírez
    ;
    Simón Alvarez
    ;
    Pamina Contreras-Kallens
    ;
    Nelson P. Barrera
    ;
    Sebastian Aguayo
      7Scopus© Citations 34
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    Multiomics characterization of methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) isolates with heterogeneous intermediate resistance to vancomycin (hVISA) in Latin America
    (2022)
    Betsy E Castro
    ;
    Rafael Rios
    ;
    Lina P Carvajal
    ;
    Mónica L Vargas
    ;
    Mónica P Cala
    <jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>Heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) compromise the clinical efficacy of vancomycin. The hVISA isolates spontaneously produce vancomycin-intermediate Staphylococcus aureus (VISA) cells generated by diverse and intriguing mechanisms.</jats:p> </jats:sec> <jats:sec> <jats:title>Objective</jats:title> <jats:p>To characterize the biomolecular profile of clinical hVISA applying genomic, transcriptomic and metabolomic approaches.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>39 hVISA and 305 VSSA and their genomes were included. Core genome-based Bayesian phylogenetic reconstructions were built and alterations in predicted proteins in VISA/hVISA were interrogated. Linear discriminant analysis and a Genome-Wide Association Study were performed. Differentially expressed genes were identified in hVISA-VSSA by RNA-sequencing. The undirected profiles of metabolites were determined by liquid chromatography and hydrophilic interaction in six CC5-MRSA.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Genomic relatedness of MRSA associated to hVISA phenotype was not detected. The change Try38 → His in Atl (autolysin) was identified in 92% of the hVISA. We identified SNPs and k-mers associated to hVISA in 11 coding regions with predicted functions in virulence, transport systems, carbohydrate metabolism and tRNA synthesis. Further, capABCDE, sdrD, esaA, esaD, essA and ssaA genes were overexpressed in hVISA, while lacABCDEFG genes were downregulated. Additionally, valine, threonine, leucine tyrosine, FAD and NADH were more abundant in VSSA, while arginine, glycine and betaine were more abundant in hVISA. Finally, we observed altered metabolic pathways in hVISA, including purine and pyrimidine pathway, CoA biosynthesis, amino acid metabolism and aminoacyl tRNA biosynthesis.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Our results show that the mechanism of hVISA involves major changes in regulatory systems, expression of virulence factors and reduction in glycolysis via TCA cycle. This work contributes to the understanding of the development of this complex resistance mechanism in regional strains.</jats:p> </jats:sec>
      1Scopus© Citations 8  3
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    Socioeconomic factors associated with antimicrobial resistance of Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli in Chilean hospitals (2008–2017)
    (2020)
    Kasim Allel
    ;
    Patricia García
    ;
    Jaime Labarca
    ;
    MUNITA SEPULVEDA, JOSE MANUEL  
    ;
    Magdalena Rendic
    To identify socioeconomic factors associated with antimicrobial resistance of Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli in Chilean hospitals (2008–2017).</p> <p><bold>Methods.</bold> We reviewed the scientific literature on socioeconomic factors associated with the emergence and dissemination of antimicrobial resistance. Using multivariate regression, we tested findings from the literature drawing from a longitudinal dataset on antimicrobial resistance from 41 major private and public hospitals and a nationally representative household survey in Chile (2008–2017). We estimated resistance rates for three priority antibiotic–bacterium pairs, as defined by the Organisation for Economic Co-operation and Development; i.e., imipenem and meropenem resistant P. aeruginosa, cloxacillin resistant S. aureus, and cefotaxime and ciprofloxacin resistant E. coli.</p> <p><bold>Results.</bold> Evidence from the literature review suggests poverty and material deprivation are important risk factors for the emergence and transmission of antimicrobial resistance. Most studies found that worse socioeconomic indicators were associated with higher rates of antimicrobial resistance. Our analysis showed an overall antimicrobial resistance rate of 32.5%, with the highest rates for S. aureus (40.6%) and the lowest for E. coli (25.7%). We found a small but consistent negative association between socioeconomic factors (income, education, and occupation) and overall antimicrobial resistance in univariate (p &lt; 0.01) and multivariate analyses (p &lt; 0.01), driven by resistant P. aeruginosa and S. aureus.</p> <p><bold>Conclusion.</bold> Socioeconomic factors beyond health care and hospital settings may affect the emergence and dissemination of antimicrobial resistance. Preventing and controlling antimicrobial resistance requires efforts above and beyond reducing antibiotic consumption.
      3Scopus© Citations 29