Browsing by Author "Ríos, Rafael"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
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(2025) Martínez, Jose; Alcalde, Manuel; Jara, Estefanía; Reyes, Jinnethe; Carvajal, Lina; Rincon, Sandra; Ríos, Rafael; Diaz, Lorena; Quesille, Ana; Riquelme, Roberto; Rivas Jiménez, Lina María; Moustafa, Ahmed; Hanson, Blake; Undurraga, Eduardo; Olivares, Jorge; García, Patricia; Araos Bralic, Rafael Ignacio; Planet, Paul; Arias, César; Munita, Jose M.El Staphylococcus aureus resistente a la meticilina (SARM) es una importante amenaza para la salud pública. La propagación global del SARM se caracteriza por sucesivas oleadas de clones epidémicos que dominan regiones geográficas específicas. Se cree que la adquisición de genes que codifican la resistencia a metales pesados (GMMP) es una característica clave en la divergencia geográfica del SARM. Sin embargo, la relación causa-efecto entre la presencia de GMMP y la divergencia de los clones de SARM aún no se ha dilucidado. En este estudio, evaluamos el papel que los GMMP pudieron haber desempeñado en la divergencia evolutiva del linaje ST5-SCC mec I del SARM en Latinoamérica. Realizamos una caracterización genómica de 113 aislamientos clínicos de SARM de seis centros de salud latinoamericanos, incluyendo 53 aislamientos recolectados en dos ciudades de Chile (Santiago y Concepción). Encontramos un plásmido (pSCL4752) que alberga genes de resistencia al arsénico, cadmio y mercurio en el 65% ( n = 71) de los aislados ST5-SCC mec I. También observamos una divergencia geográfica asociada a la presencia de pSCL4752 en aislados chilenos, con una mayor frecuencia en aislados de Concepción (88%) en comparación con Santiago (29%). Curiosamente, un análisis de reloj molecular reveló que esta divergencia se produjo tras el terremoto y tsunami de magnitud 8,8 Mw que azotó la zona de Concepción en 2010. Además, nuestros resultados demuestran que la presencia de pSCL4752 puede ser beneficiosa o perjudicial para los aislados ST5-SCC mec I, dependiendo de la disponibilidad ambiental de estos metales pesados. Nuestros resultados sugieren que la divergencia del linaje ST5-SCC mec I MRSA en América Latina podría haber sido fomentada por desastres ambientales e influenciada por la presencia/ausencia de HMRG albergados en un plásmido. IMPORTANCIA El Staphylococcus aureus resistente a la meticilina (MRSA) es una de las principales causas de infecciones potencialmente mortales en todo el mundo y una creciente preocupación para la salud pública. El aumento de bacterias resistentes a los antibióticos, como el MRSA, a menudo está vinculado a adaptaciones genéticas que mejoran su supervivencia. Nuestra investigación arroja luz sobre cómo los cambios ambientales, como los desencadenados por un desastre natural, pueden influir en la evolución y la propagación geográfica de un linaje de MRSA altamente resistente en América Latina. Identificamos un plásmido que porta genes de resistencia al arsénico, cadmio y mercurio, el cual se asoció con la divergencia geográfica del ST5-SCC mec.Se ha identificado un linaje de SARM con diferencias notables en su prevalencia entre las regiones afectadas por un gran terremoto y tsunami. Al vincular los eventos ambientales con la evolución del patógeno, nuestro estudio destaca el papel de las presiones ecológicas en la propagación del SARM. Estos hallazgos subrayan la necesidad de integrar el monitoreo ambiental en las estrategias de salud pública para comprender mejor el desafío global de la resistencia a los antimicrobianos.Publication Molecular mechanisms leading to ceftolozane/tazobactam resistance in clinical isolates of Pseudomonas aeruginosa from five Latin American countries(2022) Cadena, Elsa de la; Mojica, María F.; Ríos, Rafael; García-Betancur, Juan Carlos; Díaz, Lorena; Reyes, Jinnethe; Hernández-Gómez, Cristhian; Radice, Marcela; Gales, Ana C.; Castañeda Méndez, Paulo; Munita, José; Pallares, Cristian José; Martínez Solís, José Rodrigo Waldemar; Villegas, María VirginiaObjectives: Identify molecular mechanisms responsible for the in vitro non-susceptibility to ceftolozane/tazobactam (TOL) in a group of 158 clinical isolates of Pseudomonas aeruginosa from five Latin American countries collected before the introduction of TOL into the clinical practice. Methods: Clinical isolates of P. aeruginosa (n = 504) were collected between January 2016 and October 2017 from 20 hospitals located in Argentina, Brazil, Chile, Colombia, and Mexico. Minimum inhibitory concentrations (MICs) to TOL were determined by standard broth microdilution and interpreted according to CLSI breakpoints. Initially, production of carbapenemases in TOL non-susceptible isolates was assessed by Rapidec® followed by qPCR to detect bla KPC, bla NDM-1, bla VIM, and bla IMP. Illumina® WGS was performed for isolates in which non-susceptibility to TOL was not mediated by carbapenemases. Results: A total of 158 (31.3%) isolates were non-susceptible to TOL. In 74 (46.8%) of these isolates, non-susceptibility to TOL was explained by the production of at least one carbapenemase. WGS revealed that some isolates carried ESBLs, mutated bla PDC and ampD, associated with decreased susceptibility to TOL. Conclusion: Substitutions found in PDC and carbapenemase production were the most common presumed mechanisms of resistance to TOL detected in this study. This study shows that epidemiological surveillance is warranted to monitor the emergence of novel mechanisms of resistance to TOL that might compromise its clinical utility.Publication Multiomics characterization of methicillin-resistant Staphylococcus aureus (MRSA) isolates with heterogeneous intermediate resistance to vancomycin (hVISA) in Latin America(2023) Castro, Betsy E.; Ríos, Rafael; Carvajal, Lina P.; Vargas, Mónica L.; Cala, Mónica P.; León, Lizeth; Hanson, Blake; Dinh, An Q.; Ortega-Recalde, Oscar; Seas, Carlos; Munita, José; Arias, Cesar A.; Rincón, Sandra; Reyes, Jinnethe; Díaz, LorenaBackground: Heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) compromise the clinical efficacy of vancomycin. The hVISA isolates spontaneously produce vancomycin-intermediate Staphylococcus aureus (VISA) cells generated by diverse and intriguing mechanisms. Objective: To characterize the biomolecular profile of clinical hVISA applying genomic, transcriptomic and metabolomic approaches. Methods: 39 hVISA and 305 VSSA and their genomes were included. Core genome-based Bayesian phylogenetic reconstructions were built and alterations in predicted proteins in VISA/hVISA were interrogated. Linear discriminant analysis and a Genome-Wide Association Study were performed. Differentially expressed genes were identified in hVISA-VSSA by RNA-sequencing. The undirected profiles of metabolites were determined by liquid chromatography and hydrophilic interaction in six CC5-MRSA. Results: Genomic relatedness of MRSA associated to hVISA phenotype was not detected. The change Try38 →His in Atl (autolysin) was identified in 92% of the hVISA. We identified SNPs and k-mers associated to hVISA in 11 coding regions with predicted functions in virulence, transport systems, carbohydrate metabolism and tRNA synthesis. Further, capABCDE, sdrD, esaA, esaD, essA and ssaA genes were overexpressed in hVISA, while lacABCDEFG genes were downregulated. Additionally, valine, threonine, leucine tyrosine, FAD and NADH were more abundant in VSSA, while arginine, glycine and betaine were more abundant in hVISA. Finally, we observed altered metabolic pathways in hVISA, including purine and pyrimidine pathway, CoA biosynthesis, amino acid metabolism and aminoacyl tRNA biosynthesis. Conclusions: Our results show that the mechanism of hVISA involves major changes in regulatory systems, expression of virulence factors and reduction in glycolysis via TCA cycle. This work contributes to the understanding of the development of this complex resistance mechanism in regional strains.