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    Item type:Publication,
    Geographic divergence of methicillin-resistant Staphylococcus aureus ST5-SCCmecI in the aftermath of a major earthquake and tsunami: impact of a plasmid harboring heavy metal resistance genes
    (American Society for Microbiology, 2025-04-09)
    Jose R. W. Martínez
    ;
    Manuel Alcalde-Rico
    ;
    Estefanía Jara-Videla
    ;
    Jinnethe Reyes
    ;
    Lina P. Carvajal
    (MRSA) is a major public health menace. The global spread of MRSA is characterized by successive waves of epidemic clones dominating specific geographical regions. The acquisition of genes encoding resistance to heavy metals (HMRGs) is thought to be a key feature in the geographic divergence of MRSA. However, the cause-effect relationship between the presence of HMRGs and the divergence of MRSA clones remains to be clarified. In this study, we assessed the role that HMRGs may have played in the evolutionary divergence of the MRSA ST5-SCC <jats:italic>mec</jats:italic> I lineage in Latin America. We conducted a genomic characterization of 113 MRSA clinical isolates from six Latin American healthcare centers, including 53 isolates collected from two cities in Chile (Santiago and Concepción). We found a plasmid (pSCL4752) harboring arsenic, cadmium, and mercury resistance genes in 65% ( <jats:italic>n</jats:italic> = 71) of the ST5-SCC <jats:italic>mec</jats:italic> I isolates. We also observed a geographic divergence associated with the presence of pSCL4752 in Chilean isolates, with a higher frequency in isolates from Concepción (88%) compared to Santiago (29%). Interestingly, a molecular clock analysis revealed that this divergence occurred in the aftermath of an 8.8 Mw earthquake and tsunami that struck the Concepción area in 2010. Moreover, our results demonstrate that the carriage of pSCL4752 can be beneficial or detrimental for ST5-SCC <jats:italic>mec</jats:italic> I isolates, depending on the environmental availability of these heavy metals. Our results suggest that the divergence of the ST5-SCC <jats:italic>mec</jats:italic> I MRSA lineage in Latin America could have been fostered by environmental disasters and influenced by the presence/absence of HMRGs harbored in a plasmid. </jats:p> <jats:sec> <jats:title>IMPORTANCE</jats:title> <jats:p> Methicillin-resistant <jats:italic>Staphylococcus aureus</jats:italic> (MRSA) is a major cause of life-threatening infections worldwide and a growing public health concern. The rise of antibiotic-resistant bacteria, such as MRSA, is often linked to genetic adaptations that enhance their survival. Our research sheds light on how environmental changes, such as those triggered by a natural disaster, can influence the evolution and geographic spread of a highly resistant MRSA lineage in Latin America. We identified a plasmid carrying genes for resistance to arsenic, cadmium, and mercury, which was associated with the geographic divergence of the ST5-SCC <jats:italic>mec</jats:italic> I MRSA lineage, with striking differences in its prevalence between regions affected by a major earthquake and tsunami. By linking environmental events to pathogen evolution, our study highlights the role of ecological pressures in the spread of MRSA. These findings emphasize the need to integrate environmental monitoring into public health strategies to better understand the global challenge of antimicrobial resistance.
      4
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    Item type:Publication,
    Isolation of Ciprofloxacin and Ceftazidime-Resistant Enterobacterales From Vegetables and River Water Is Strongly Associated With the Season and the Sample Type
    (2021)
    Constanza Díaz-Gavidia
    ;
    Carla Barría
    ;
    ;
    Patricia García
    ;
    Francisca P. Alvarez
    <jats:p>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 <jats:italic>mcr-1</jats:italic> and extended spectrum β-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 <jats:italic>Escherichia coli</jats:italic> (<jats:italic>n</jats:italic>=109), <jats:italic>Citrobacter</jats:italic> sp. (<jats:italic>n</jats:italic>=20), <jats:italic>Enterobacter cloacae</jats:italic> complex (<jats:italic>n</jats:italic>=8), <jats:italic>Klebsiella pneumoniae</jats:italic> (<jats:italic>n</jats:italic>=8), and <jats:italic>Klebsiella aerogenes</jats:italic> (<jats:italic>n</jats:italic>=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 <jats:italic>E. coli</jats:italic> isolates (1.29%), the gene <jats:italic>mcr-1</jats:italic> was found and ESBL genes were found in 23/62 isolates (37%), with <jats:italic>bla</jats:italic><jats:sub>CTX-M</jats:sub> 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.</jats:p>
      1Scopus© Citations 28
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    Scopus© Citations 21  2
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    Real-World Performance of Susceptibility Testing for Ceftolozane/Tazobactam against Non-Carbapenemase-Producing Carbapenem-Resistant Pseudomonas aeruginosa
    (2022) ;
    Manuel Alcalde-Rico
    ;
    José R. W. Martínez
    ;
    María Victoria Moreno
    ;
    Pamela Rojas
    <jats:p> Ceftolozane/tazbactam (C/T) is a potent anti-pseudomonal agent that has clinical utility against infections caused by non-carbapenemase, producing-carbapenem-resistant <jats:named-content content-type="genus-species">Pseudomonas aeruginosa</jats:named-content> (non-CP-CR-PA). Accurate, precise, and reliable antimicrobial susceptibility testing (AST) is crucial to guide clinical decisions. </jats:p>
      19Scopus© Citations 2
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    Item type:Publication,
    A Multicenter Study To Evaluate Ceftaroline Breakpoints: Performance in an Area with High Prevalence of Methicillin-Resistant Staphylococcus aureus Sequence Type 5 Lineage
    (2019)
    Ayesha Khan
    ;
    Lina M. Rivas
    ;
    Maria Spencer
    ;
    Rodrigo Martinez
    ;
    Marusella Lam
    <jats:p> Ceftaroline (CPT) is a broad-spectrum agent with potent activity against methicillin-resistant <jats:named-content content-type="genus-species">Staphylococcus aureus</jats:named-content> (MRSA). The sequence type 5 (ST5) Chilean-Cordobés clone, associated with CPT nonsusceptibility, is dominant in Chile, a region with high rates of MRSA infections. </jats:p>
      1Scopus© Citations 7  1