Publication:

Reconstruction of the evolution of the Chilean-Cordobes clone of methicilin resistant: Staphylococcus aureus in Latin America

The global dissemination of methicillin-resistant Staphylococcus aureus (MRSA) is associated with the emergence and establishment of clones in specific geographic areas. The MRSA Chilean-Cordobes clone (ChC) predominated widely throughout several countries of Latin America, but during the mid-2000s the USA300-SAE clone quickly replaced the ChC in Colombia and Ecuador. Most notably, this replacement was not observed in Peru or Chile, where the ChC remains as the most frequent clone. Here, we aimed to perform a phylogenomic reconstruction of the evolution of the ChC in Latin America and to estimate the effect on the fitness of genetic features that are particular to the ChC clone from Chile. To achieve this aim, we sequenced 925 genomes of MRSA strains from Latin America. First, we performed whole genome sequencing and confirmed that the ChC clone remains the most frequent clone in our country. However, this lineage has been gradually replaced, in a nontypical MRSA clonal replacement event, by new emerging clones (ST105-SCCmecII and ST72-SCCmecVI). Then, we explore the impact of heavy metal resistance genes in the evolution of the ChC clone and provide evidence to suggest a possible link between the release of high quantities of heavy metals in the aftermath of an environmental disaster and the divergent evolution of the ChC in Latin America. Finally, we found evidence that the Sau1 restriction modification system plays a key role in the genomic evolution of the Chilean-Cordobes clone in Latin America by increasing the acquisition of foreign DNA. Overall, these results have the potential to greatly enhance our understanding of MRSA dissemination and contribute to improved approaches for combating this pathogen in Chile and Latin America.