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Author: search.filters.author.Carmen VarelaSubject: search.filters.subject.genome analysis

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    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
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    Genomic analysis of the diversity, antimicrobial resistance and virulence potential of clinical Campylobacter jejuni and Campylobacter coli strains from Chile
    (2021)
    Veronica Bravo
    ;
    Assaf Katz
    ;
    PORTE TORRE, LORENA ISABEL  
    ;
    WEITZEL, THOMAS  
    ;
    Carmen Varela
    <jats:p><jats:italic>Campylobacter jejuni</jats:italic> and <jats:italic>Campylobacter coli</jats:italic> are the leading cause of human gastroenteritis in the industrialized world and an emerging threat in developing countries. The incidence of campylobacteriosis in South America is greatly underestimated, mostly due to the lack of adequate diagnostic methods. Accordingly, there is limited genomic and epidemiological data from this region. In the present study, we performed a genome-wide analysis of the genetic diversity, virulence, and antimicrobial resistance of the largest collection of clinical <jats:italic>C</jats:italic>. <jats:italic>jejuni</jats:italic> and <jats:italic>C</jats:italic>. <jats:italic>coli</jats:italic> strains from Chile available to date (n = 81), collected in 2017–2019 in Santiago, Chile. This culture collection accounts for more than one third of the available genome sequences from South American clinical strains. cgMLST analysis identified high genetic diversity as well as 13 novel STs and alleles in both <jats:italic>C</jats:italic>. <jats:italic>jejuni</jats:italic> and <jats:italic>C</jats:italic>. <jats:italic>coli</jats:italic>. Pangenome and virulome analyses showed a differential distribution of virulence factors, including both plasmid and chromosomally encoded T6SSs and T4SSs. Resistome analysis predicted widespread resistance to fluoroquinolones, but low rates of erythromycin resistance. This study provides valuable genomic and epidemiological data and highlights the need for further genomic epidemiology studies in Chile and other South American countries to better understand molecular epidemiology and antimicrobial resistance of this emerging intestinal pathogen.</jats:p>
    Scopus© Citations 23  4
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    Genomic Analysis of Chilean Strains of Campylobacter jejuni from Human Faeces
    (2019)
    Arturo Levican
    ;
    Ignacio Ramos-Tapia
    ;
    Isabel Briceño
    ;
    Francisco Guerra
    ;
    Benjamin Mena
    <jats:p><jats:italic>Campylobacter</jats:italic>spp., especially<jats:italic>C. jejuni</jats:italic>, are recognized worldwide as the bacterial species that most commonly cause food-related diarrhea.<jats:italic>C. jejuni</jats:italic>possesses many different virulence factors, has the ability to survive in different reservoirs, and has shown among isolates the emergence of Antimicrobial Resistance (AMR). Genome association analyses of this bacterial pathogen have contributed to a better understanding of its pathogenic and AMR associated determinants. However, the epidemiological information of these bacteria in Latin American countries is scarce and no genomic information is available in public databases from isolates in these countries. Considering this, the present study is aimed to describe the genomic traits from representative<jats:italic>Campylobacter</jats:italic>spp. strains recovered from faecal samples of patients with acute diarrhoea from Valparaíso, Chile.<jats:italic>Campylobacter</jats:italic>spp. was detected from the faeces of 28 (8%) out of 350 patients with acute diarrhoea, mainly from young adults and children, and 26 (93%) of the isolates corresponded to<jats:italic>C. jejuni</jats:italic>. 63% of the isolates were resistant to ciprofloxacin, 25.9% to tetracycline, and 3.5% to erythromycin. Three isolates were selected for WGS on the basis of their<jats:italic>flaA</jats:italic>-RFLP genotype. They belonged to the multilocus sequence typing (MLST) clonal clomplex (CC) 21(PUCV-1), CC-48 (PUCV-3), and CC-353 (PUCV-2) and presented several putative virulence genes, including the Type IV and Type VI Secretion Systems, as well as AMR-associated genes in agreement with their susceptibility pattern. On the basis of the wgMLST, they were linked to strains from poultry and ruminants. These are the first genomes of Chilean<jats:italic>C. jejuni</jats:italic>isolates available in public databases and they provide relevant information about the<jats:italic>C. jejuni</jats:italic>isolates associated with human infection in this country.</jats:p>
      28Scopus© Citations 18