Browsing by Author "Alvarez, Francisca P."

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    Environmental and anthropogenic factors associated with the likelihood of detecting Salmonella in agricultural watersheds
    (2022) Toro, Magaly; Weller, Daniel; Ramos, Romina; Diaz, Leonela; Alvarez, Francisca P.; Reyes-Jara, Angelica; Moreno-Switt, Andrea I.; Meng, Jianghong; Adell, Aiko D.
    Surface water is one of the primary sources of irrigation water for produce production; therefore, its contamination by foodborne pathogens, such as Salmonella, may substantially impact public health. In this study, we determined the presence of Salmonella in surface water and characterized the relationship between Salmonella detection and environmental and anthropogenic factors. From April 2019 to February 2020, 120 samples from 30 sites were collected monthly in four watersheds located in two different central Chile agricultural regions (N =1080). Water samples from rivers, canals, streams, and ponds linked to each watershed were obtained. Surface water (10 L) was filtrated in situ, and samples were analyzed for the presence of Salmonella. Salmonella was detected every month in all watersheds, with a mean detection percentage of 28% (0%-90%) across sampling sites, regardless of the season. Overall, similar detection percentages were observed for both regions: 29.1% for Metropolitan and 27.0% for Maule. Salmonella was most often detected in summer (39.8% of all summer samples tested positive) and least often in winter (14.4% of winter samples). Random forest analysis showed that season, water source, and month, followed by latitude and river, were the most influential factors associated with Salmonella detection. The influences of water pH and temperature (categorized as environmental factors) and factors associated with human activity (categorized as anthropogenic factors) registered at the sampling site were weakly or not associated with Salmonella detection. In conclusion, Salmonella was detected in surface water potentially used for irrigation, and its presence was linked to season and water source factors. Interventions are necessary to prevent contamination of produce, such as water treatment before irrigation.
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    Genomic characterisation of the population structure and antibiotic resistance of Salmonella enterica serovar Infantis in Chile, 2009-2022
    (2024) Pina-Iturbe, Alejandro; Diaz-Gavidia, Constanza; Alvarez, Francisca P.; Barron-Montenegro, Rocio; Alvarez-Espejo, Diana M.; Garcia, Patricia; Solis, Doina; Constenla-Albornoz, Rodrigo; Toro, Magaly; Olivares-Pacheco, Jorge; Reyes-Jara, Angelica; Meng, Jianghong; Bell, Rebecca L.; Moreno-Switt, Andrea I.
    Background Multidrug-resistant (MDR) Salmonella Infantis has disseminated worldwide, mainly linked to the consumption of poultry products. Evidence shows dissemination of this pathogen in Chile; however, studies are primarily limited to phenotypic data or involve few isolates. As human cases of Salmonella Infantis infections have substantially increased in recent years, this study aimed to characterise the genomic epidemiology and antimicrobialresistance profiles of isolates obtained from different sources, aiming to inform effective surveillance and control measures. Methods We sequenced 396 Salmonella Infantis genomes and analysed them with all publicly available genomes of this pathogen from Chile (440 genomes in total), representing isolates from environmental, food, animal, and human sources obtained from 2009 to 2022. Based on bioinformatic and phenotypic methods, we assessed the population structure, dissemination among different niches, and antimicrobial resistance (AMR) profiles of Salmonella Infantis in the country. Findings The genomic and phylogenetic analyses showed that Salmonella Infantis from Chile comprised several clusters of highly related isolates dominated by sequence type 32. The HC20_343 cluster grouped an important proportion of all isolates. This was the only cluster associated with pESI-like megaplasmids, and up to 12 acquired AMR genes/mutations predicted to result in an MDR phenotype. Accordingly, antimicrobial -susceptibility testing revealed a strong concordance between the AMR genetic determinants and their matching phenotypic expression, indicating that a significant proportion of HC20_343 isolates produce extended -spectrum beta-lactamases and have intermediate fluoroquinolone resistance. HC20_343 Salmonella Infantis were spread among environmental, animal, food, and human niches, showing a close relationship between isolates from different years and sources, and a low intra-source genomic diversity. Interpretation Our findings show a widespread dissemination of MDR Salmonella Infantis from the HC20_343 cluster in Chile. The high proportion of isolates with resistance to first -line antibiotics and the evidence of active transmission between the environment, animals, food, and humans highlight the urgency of improved surveillance and control measures in the country. As HC20_343 isolates predominate in the Americas, our results suggest a high prevalence of ESBL-producing Salmonella Infantis with intermediate fluoroquinolone resistance in the continent.
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    Integrative genome-centric metagenomics for surface water surveillance: Elucidating microbiomes, antimicrobial resistance, and their associations
    (2024) Huang, Xinyang; Toro, Magaly; Reyes-Jara, Angelica; Moreno-Switt, Andrea, I; Adell, Aiko; Oliveira, Celso J. B.; Bonelli, Raquel R.; Gutierrez, Sebastian; Alvarez, Francisca P.; Rocha, Alan Douglas de Lima; Kraychete, Gabriela B.; Chen, Zhao; Grim, Christopher; Brown, Eric; Bell, Rebecca; Meng, Jianghong
    Surface water ecosystems are intimately intertwined with anthropogenic activities and have significant public health implications as primary sources of irrigation water in agricultural production. Our extensive metagenomic analysis examined 404 surface water samples from four different geological regions in Chile and Brazil, spanning irrigation canals (n = 135), rivers (n = 121), creeks (n = 74), reservoirs (n = 66), and ponds (n = 8). Overall, 50.25 % of the surface water samples contained at least one of the pathogenic or contaminant bacterial genera (Salmonella: 29.21 %; Listeria: 6.19 %; Escherichia: 35.64 %). Furthermore, a total of 1,582 antimicrobial resistance (AMR) gene clusters encoding resistance to 25 antimicrobial classes were identified, with samples from Brazil exhibiting an elevated AMR burden. Samples from stagnant water sources were characterized by dominant Cyanobacteriota populations, resulting in significantly reduced biodiversity and more uniform community compositions. A significant association between taxonomic composition and the resistome was supported by a Procrustes analysis (p < 0.001). Notably, regional signatures were observed regarding the taxonomic and resistome profiles, as samples from the same region clustered together on both ordinates. Additionally, network analysis illuminated the intricate links between taxonomy and AMR at the contig level. Our deep sequencing efforts not only mapped the microbial landscape but also expanded the genomic catalog with newly characterized metagenome-assembled genomes (MAGs), boosting the classification of reads by 12.85%. In conclusion, this study underscores the value of metagenomic approaches in surveillance of surface waters, enhancing our understanding of microbial and AMR dynamics with far-reaching public health and ecological ramifications.
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    Isolation of Ciprofloxacin and Ceftazidime-Resistant Enterobacterales From Vegetables and River Water Is Strongly Associated With the Season and the Sample Type
    (FRONTIERS MEDIA SA, 2021) Diaz Gavidia, Constanza; Barria, Carla; Rivas, Lina; Garcia, Patricia; Alvarez, Francisca P.; Gonzalez Rocha, Gerardo; Opazo Capurro, Andres; Araos, Rafael; Munita, Jose M.; Cortes, Sandra; Olivares Pacheco, Jorge; Adell, Aiko D.; Moreno Switt, Andrea I.
    The dissemination of antibiotic-resistant bacteria (ARB) from water used for crop irrigation to vegetables is poorly studied. During a year, five farmer markets in a city in Central Chile were visited, and 478 vegetable samples (parsleys, corianders, celeries, lettuces, chards, and beets) were collected. Simultaneously, 32 water samples were collected from two rivers which are used to irrigate the vegetables produced in the area. Resistant Enterobacterales were isolated and identified. Colistin resistance gene mcr-1 and extended spectrum beta-lactamases (ESBL) were molecularly detected. The association of environmental factors was evaluated, with the outcomes being the presence of Enterobacterales resistant to four antibiotic families and the presence of multidrug resistance (MDR) phenotypes. Parsley, coriander, and celery showed the highest prevalence of resistant Enterobacterales (41.9% for ciprofloxacin and 18.5% for ceftazidime). A total of 155 isolates were obtained, including Escherichia coli (n = 109), Citrobacter sp. (n = 20), Enterobacter cloacae complex (n = 8), Klebsiella pneumoniae (n = 8), and Klebsiella aerogenes (n = 1). Resistance to ampicillin (63.2%) and ciprofloxacin (74.2%) was most frequently found; 34.5% of the isolates showed resistance to third-generation cephalosporins, and the MDR phenotype represented 51.6% of the isolates. In two E. coli isolates (1.29%), the gene mcr-1 was found and ESBL genes were found in 23/62 isolates (37%), with bla(CTX-M) being the most frequently found in 20 isolates (32%). Resistant Enterobacterales isolated during the rainy season were less likely to be MDR as compared to the dry season. Understanding environmental associations represent the first step toward an improved understanding of the public health impact of ARB in vegetables and water.
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    Perspective on Clinically-Relevant Antimicrobial Resistant Enterobacterales in Food: Closing the Gaps Using Genomics
    (FRONTIERS MEDIA SA, 2021) Diaz Gavidia, Constanza; Alvarez, Francisca P.; Munita, Jose M.; Cortes, Sandra; Moreno Switt, Andrea, I
    Antimicrobial resistance is one of the most important public health concerns-it causes 700,000 deaths annually according to the World Health Organization (WHO). Enterobacterales such as E. coli and Klebsiella pneumoniae, have become resistant to many relevant antimicrobials including carbapenems and extended spectrum cephalosporins. These clinically relevant resistant Enterobacterales (CRRE) members are now globally distributed in the environment including different food types (meats, produce, dairy). Unlike known foodborne pathogens, CRRE are not usually part of most food surveillance systems. However, numerous reports of CRRE highlight the importance of these bacteria in food and have been shown to contribute to the overall crisis of antimicrobial resistance. This is especially important in the context of carriage of these pathogens by immuno-compromised individuals. CRRE infections upon consumption of contaminated food could colonize the human gastrointestinal tract and eventually be a source of systemic infections such as urinary tract infections or septicemia. While different aspects need to be considered to elucidate this, whole genome sequencing along with metadata could be used to understand genomic relationships of CRRE obtained from foods and humans, including isolates from clinical infections. Once robust scientific data is available on the role of CRRE in food, countries could move forward to better survey and control CRRE in food.