CRIS

Permanent URI for this communityhttps://investigadores.udd.cl/handle/123456789/1

Browse

Settings

Author: search.filters.author.Juan A. UgaldeHas files: No

Search Results

Now showing 1 - 8 of 8
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Atmospheric Dispersal and Local Drivers Shape Snow and Air Microbial Communities in the Western Antarctic Peninsula
    (Wiley, 2026-05)
    ALCAMAN ARIAS, MARIA ESTRELLA  
    ;
    Ignacio Ramos‐Tapia
    ;
    Francisco Fuentes
    ;
    Roberto Bastías
    ;
    Carlos A. Manzano
    <jats:title>ABSTRACT</jats:title> <jats:p>Microbial communities in Antarctica's snow and atmosphere are critical for nutrient cycling and are highly sensitive to environmental change. We characterised the bacterial composition, diversity, and co‐occurrence network structure of surface snow and airborne microbiomes from two contrasting bays along the Western Antarctic Peninsula (WAP): Arturo Prat Base (APB; Chile Bay, Greenwich Island) and Yelcho Base (YB; South Bay, Doumer Island), sampled during consecutive austral summers (2022–2023). Surface snow and air samples were analysed using 16S rRNA gene sequencing, diversity indices, and network analyses to evaluate spatial and interannual dynamics. Proteobacteria and Bacteroidota dominated both environments, but community structures differed between sites: APB showed stronger local and anthropogenic signals near logistic stations, whereas YB reflected more stable deposition regimes and distant atmospheric inputs. Airborne communities displayed limited interannual variation and high compositional similarity between sites, consistent with atmospheric seeding by polar air masses. Co‐occurrence networks revealed denser, more structured interactions within snow communities, with keystone taxa linking snow and air, sustaining deposition–resuspension dynamics. These findings highlight that long‐range atmospheric transport and local conditions shape Antarctic microbial dynamics, providing insights for forecasting microbiome responses and assessing airborne health risks amid human activity and climate change in polar regions.</jats:p>
      1
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Pseudomonas gelidaquae sp. nov., an Antarctic bacterium with a distinctive Type III Secretion System, isolated from Fildes Bay, King George Island
    (Springer Science and Business Media LLC, 2025-09-24)
    Sebastián Higuera-Llantén
    ;
    María S. Pavlov
    ;
    Leandro P. de Sousa
    ;
    Felipe Vásquez-Ponce
    ;
    Juan Parás-Silva
      8Scopus© Citations 1
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Multispecies emergence of dual blaKPC/NDM carbapenemase-producing Enterobacterales recovered from invasive infections in Chile
    (American Society for Microbiology, 2025-01-31)
    QUESILLE VILLALOBOS, ANA MARIA  
    ;
    Camila Solar
    ;
    Jose R. W. Martínez
    ;
    RIVAS JIMENEZ, LINA MARIA  
    ;
    Valeria Quiroz
    Carbapenemase-producing carbapenem-resistant Enterobacterales (CP-CRE) represent a significant global threat. The emergence of dual CP-CRE is particularly alarming, as they can potentially compromise the efficacy of newer antibiotics, further decreasing therapeutic alternatives. Herein, we report the emergence of multiple species of CP-CRE recovered from invasive infections in Chile that simultaneously harbor and provide an in-depth genomic characterization of these worrisome pathogens. We collected carbapenem-resistant Enterobacterales (CRE) isolates from invasive infections over a 4-year period, across 11 healthcare centers in Chile. Bacterial species and the presence of carbapenemase genes were confirmed using MALDI-TOF and PCR assays, respectively. Antimicrobial susceptibility testing was conducted through disk diffusion and broth microdilution methods. Dual CP-CRE isolates were subjected to short- and long-read whole genome sequencing to perform a detailed genomic characterization of the isolates and of the mobile genetic elements harboring the enzymes. From a total of 1,335 CRE isolates, we observed an increase in the prevalence of CP-CRE, from 11% in 2019 to 38% in 2022. A total of 11 dual CP-CRE isolates were recovered, all of them harboring
    Scopus© Citations 10  15
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Whole-genome sequencing reveals changes in genomic diversity and distinctive repertoires of T3SS and T6SS effector candidates in Chilean clinical Campylobacter strains
    (2023)
    Assaf Katz
    ;
    Lorena Porte  
    ;
    WEITZEL, THOMAS  
    ;
    Carmen Varela
    ;
    Cristina Muñoz-Rehbein
    <jats:p><jats:italic>Campylobacter</jats:italic> is the leading cause of bacterial gastroenteritis worldwide and an emerging and neglected pathogen in South America. This zoonotic pathogen colonizes the gastrointestinal tract of a wide range of mammals and birds, with poultry as the most important reservoir for human infections. Apart from its high morbidity rates, the emergence of resistant strains is of global concern. The aims of this work were to determine genetic diversity, presence of antimicrobial resistance determinants and virulence potential of <jats:italic>Campylobacter</jats:italic> spp. isolated from patients with acute gastrointestinal disease at ‘Clinica Alemana’, Santiago de Chile. The study considered the isolation of <jats:italic>Campylobacter</jats:italic> spp., from stool samples during a 20-month period (January 2020 to September 2021). We sequenced (NextSeq, Illumina) and performed an in-depth analysis of the genome sequences of 88 <jats:italic>Campylobacter jejuni</jats:italic> and 2 <jats:italic>Campylobacter</jats:italic> coli strains isolated from clinical samples in Chile. We identified a high genetic diversity among C. je<jats:italic>juni</jats:italic> strains and the emergence of prevalent clonal complexes, which were not identified in our previous reports. While ~40% of strains harbored a mutation in the gyrA gene associated with fluoroquinolone resistance, no macrolide-resistance determinants were detected. Interestingly, gene clusters encoding virulence factors such as the T6SS or genes associated with long-term sequelae such as Guillain-Barré syndrome showed lineage-relatedness. In addition, our analysis revealed a high degree of variability regarding the presence of fT3SS and T6SS effector proteins in comparison to type strains 81-176, F38011, and NCTC 11168 and 488. Our study provides important insights into the molecular epidemiology of this emerging foodborne pathogen. In addition, the differences observed regarding the repertoire of fT3SS and T6SS effector proteins could have an impact on the pathogenic potential and transmissibility of these Latin American isolates, posing another challenge in characterizing the infection dynamics of this emergent and neglected bacterial pathogen.</jats:p>
      29Scopus© Citations 8
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Reduced microbial diversity of the nasopharyngeal microbiome in household contacts with latent tuberculosis infection
    (2023)
    Cinthya Ruiz-Tagle
    ;
    Juan A. Ugalde
    ;
    Rodrigo Naves
    ;
    ARAOS BRALIC, RAFAEL IGNACIO  
    ;
    Patricia García
    <jats:title>Abstract</jats:title><jats:p>The upper respiratory tract is an obliged pathway for respiratory pathogens and a healthy microbiota may support the host's mucosal immunity preventing infection. We analyzed the nasopharyngeal microbiome in tuberculosis household contacts (HHCs) and its association with latent tuberculosis infection (TBI). A prospective cohort of HHCs was established and latent TBI status was assessed by serial interferon-γ release assay (IGRA). Nasopharyngeal swabs collected at baseline were processed for 16S rRNA gene sequencing. The 82 participants included in the analysis were classified as: (a) non-TBI [IGRA negative at baseline and follow-up, no active TB (n = 31)], (b) pre-TBI [IGRA negative at baseline but converted to IGRA positive or developed active TB at follow-up (n = 16)], and (c) TBI [IGRA positive at enrollment (n = 35)]. Predominant phyla were <jats:italic>Actinobacteriota</jats:italic>, <jats:italic>Proteobacteria</jats:italic>, <jats:italic>Firmicutes</jats:italic> and <jats:italic>Bacteroidota</jats:italic>. TBI group had a lower alpha diversity compared to non-TBI (p<jats:sub>adj</jats:sub> = 0.04) and pre-TBI (p<jats:sub>adj</jats:sub> = 0.04). Only TBI and non-TBI had beta diversity differences (p<jats:sub>adj</jats:sub> = 0.035). Core microbiomes’ had unique genera, and genus showed differential abundance among groups. HHCs with established latent TBI showed reduced nasopharyngeal microbial diversity with distinctive taxonomical composition. Whether a pre-existing microbiome feature favors, are a consequence, or protects against <jats:italic>Mycobacterium tuberculosis</jats:italic> needs further investigation.</jats:p>
    Scopus© Citations 3  3
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Role of the multi-drug efflux systems on the baseline susceptibility to ceftazidime/avibactam and ceftolozane/tazobactam in clinical isolates of non-carbapenemase-producing carbapenem-resistant Pseudomonas aeruginosa
    (2022)
    María José Contreras-Gómez
    ;
    José R. W. Martinez
    ;
    RIVAS JIMENEZ, LINA MARIA  
    ;
    Juan A. Ugalde
    ;
    Roberto Riquelme-Neira  
    <jats:p>Carbapenem-resistant <jats:italic>Pseudomonas aeruginosa</jats:italic> (CRPA) is one of the pathogens that urgently needs new drugs and new alternatives for its control. The primary strategy to combat this bacterium is combining treatments of beta-lactam with a beta-lactamase inhibitor. The most used combinations against <jats:italic>P. aeruginosa</jats:italic> are ceftazidime/avibactam (CZA) and ceftolozane/tazobactam (C/T). Although mechanisms leading to CZA and C/T resistance have already been described, among which are the resistance-nodulation-division (RND) efflux pumps, the role that these extrusion systems may play in CZA, and C/T baseline susceptibility of clinical isolates remains unknown. For this purpose, 161 isolates of non-carbapenemase-producing (Non-CP) CRPA were selected, and susceptibility tests to CZA and C/T were performed in the presence and absence of the RND efflux pumps inhibitor, Phenylalanine-arginine β-naphthylamide (PAβN). In the absence of PAβN, C/T showed markedly higher activity against Non-CP-CRPA isolates than observed for CZA. These results were even more evident in isolates classified as extremely-drug resistant (XDR) or with difficult-to-treat resistance (DTR), where CZA decreased its activity up to 55.2% and 20.0%, respectively, whereas C/T did it up to 82.8% (XDR), and 73.3% (DTR). The presence of PAβN showed an increase in both CZA (37.6%) and C/T (44.6%) activity, and 25.5% of Non-CP-CRPA isolates increased their susceptibility to these two combined antibiotics. However, statistical analysis showed that only the C/T susceptibility of Non-CP-CRPA isolates was significantly increased. Although the contribution of RND activity to CZA and C/T baseline susceptibility was generally low (two-fold decrease of minimal inhibitory concentrations [MIC]), a more evident contribution was observed in a non-minor proportion of the Non-CP-CRPA isolates affected by PAβN [CZA: 25.4% (15/59); C/T: 30% (21/70)]. These isolates presented significantly higher MIC values for C/T. Therefore, we conclude that RND efflux pumps are participating in the phenomenon of baseline susceptibility to CZA and, even more, to C/T. However, the genomic diversity of clinical isolates is so great that deeper analyzes are necessary to determine which elements are directly involved in this phenomenon.</jats:p>
      1Scopus© Citations 7
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Scopus© Citations 7  1
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Scopus© Citations 14  2