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    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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    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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    Multisite Detection of Tn
    <i>1549</i>
    -Mediated
    <i>vanB</i>
    Vancomycin Resistance in Multidrug-Resistant Enterococcus faecalis ST6 in Texas and Florida
    (2023)
    Shelby R. Simar
    ;
    Truc T. Tran
    ;
    Kirsten B. Rydell
    ;
    Diana Panesso
    ;
    German A. Contreras
    <jats:p> In the United States, <jats:italic>vanB</jats:italic> -mediated resistance in enterococci is rare. We characterized three sequence type (ST) 6, vancomycin-resistant <jats:named-content content-type="genus-species">Enterococcus faecalis</jats:named-content> isolates causing bacteremia in unique patients in spatiotemporally distinct settings. </jats:p>
      7  1Scopus© Citations 3
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    New Perspectives on Antimicrobial Agents: Long-Acting Lipoglycopeptides
    (2022)
    Truc T. Tran
    ;
    Sara Gomez Villegas
    ;
    Samuel L. Aitken
    ;
    Susan M. Butler-Wu
    ;
    Alex Soriano
    <jats:p>The long-acting lipoglycopeptides (LGPs) dalbavancin and oritavancin are semisynthetic antimicrobials with broad and potent activity against Gram-positive bacterial pathogens. While they are approved by the Food and Drug Administration for acute bacterial skin and soft tissue infections, their pharmacological properties suggest a potential role of these agents for the treatment of deep-seated and severe infections, such as bloodstream and bone and joint infections.</jats:p>
      5Scopus© Citations 29
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    Detection of heterogeneous vancomycin intermediate resistance in MRSA isolates from Latin America
    (2020)
    Betsy E Castro
    ;
    Maritza Berrio
    ;
    Monica L Vargas
    ;
    Lina P Carvajal
    ;
    Lina V Millan
    <jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Vancomycin is a common first-line option for MRSA infections. The heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) phenotype is associated with therapeutic failure. However, hVISA isolates are usually reported as vancomycin susceptible by routine susceptibility testing procedures.</jats:p></jats:sec><jats:sec><jats:title>Objectives</jats:title><jats:p>To detect and characterize the hVISA phenotype in MRSA isolates causing infections in nine Latin American countries.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>We evaluated a total of 1189 vancomycin-susceptible MRSA isolates recovered during 2006–08 and 2011–14. After an initial screening of hVISA using glycopeptide-supplemented agar strategies, the detection of hVISA was performed by Etest (GRD) and Macro-method (MET). Isolates deemed to be hVISA were subjected to population analysis profile/AUC (PAP/AUC) and WGS for further characterization. Finally, we interrogated alterations in predicted proteins associated with the development of the VISA phenotype in both hVISA and vancomycin-susceptible S. aureus (VSSA) genomes.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>A total of 39 MRSA isolates (3.3%) were classified as hVISA (1.4% and 5.6% in MRSA recovered from 2006–08 and 2011–14, respectively). Most of the hVISA strains (95%) belonged to clonal complex (CC) 5. Only 6/39 hVISA isolates were categorized as hVISA by PAP/AUC, with 6 other isolates close (0.87–0.89) to the cut-off (0.9). The majority of the 39 hVISA isolates exhibited the Leu-14→Ile (90%) and VraT Glu-156→Gly (90%) amino acid substitutions in WalK. Additionally, we identified 10 substitutions present only in hVISA isolates, involving WalK, VraS, RpoB and RpoC proteins.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>The hVISA phenotype exhibits low frequency in Latin America. Amino acid substitutions in proteins involved in cell envelope homeostasis and RNA synthesis were commonly identified. Our results suggest that Etest-based methods are an important alternative for the detection of hVISA clinical isolates.</jats:p></jats:sec>
      3  1Scopus© Citations 14
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      1Scopus© Citations 36
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    Scopus© Citations 31  2
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    Scopus© Citations 14  2