RESUMO
Objectives: We investigated the amino acid substitutions in the GES family of ESBLs that were most likely to be involved in the evolution of carbapenemase activity. Methods: To identify the substitutions that are functionally important, we analysed the evolutionary history of the GES ß-lactamases using an alignment and phylogeny to identify sites in GES that show evidence of positive selection and the selected phenotypes. Results and Conclusions: Data indicate that the substitutions G170S and G243A are associated with carbapenemase activity. The substitutions Q43E, E104K and T237A are most likely associated with ESBL activity.
RESUMO
OBJECTIVES: Pseudomonas aeruginosa is one of the leading causes of healthcare-associated infections globally. High-risk carbapenemase-encoding P. aeruginosa clones are disseminating in many regions. The aim of this study was to learn more about the lineages and mechanisms of resistance of P. aeruginosa circulating in Peru. METHODS: A total of 141 carbapenemase-producing isolates recovered from hospitalized and ambulatory patients in Lima were sequenced and analyzed to infer their lineages through whole-genome sequence typing (wgST) and to identify their antimicrobial resistance genes. RESULTS: wgST identified nine sequence types (STs); ST111 and ST357 were the most frequently encountered (44.0% and 38.3%, respectively), followed by ST179 (8.5%), with the remaining six detected only sporadically. Among ST357 isolates, 96.3% carried the novel blaIMP-93 allele, whereas the remainder harbored blaIMP-74. 74.2% of ST111 isolates co-harbored blaIMP-18 and blaVIM-2, while the rest carried either of these genes individually. All other ST lineages carried a single carbapenemase, which was either blaIMP-16, blaIMP-74, or blaVIM-2. CONCLUSION: Our study shows that the high-risk P. aeruginosa clones ST357, which harbors the novel blaIMP-93, and ST111, which carries blaIMP-18 and blaVIM-2, have apparently become endemic in the region.
Assuntos
Infecções por Pseudomonas , Pseudomonas aeruginosa , Humanos , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Carbapenêmicos , Testes de Sensibilidade Microbiana , Peru , Pseudomonas aeruginosa/genética , Infecções por Pseudomonas/epidemiologia , Infecções por Pseudomonas/tratamento farmacológicoRESUMO
BACKGROUND: The community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) epidemic in the United States is attributed to the spread of the USA300 clone. An epidemic of CA-MRSA closely related to USA300 has occurred in northern South America (USA300 Latin-American variant, USA300-LV). Using phylogenomic analysis, we aimed to understand the relationships between these 2 epidemics. METHODS: We sequenced the genomes of 51 MRSA clinical isolates collected between 1999 and 2012 from the United States, Colombia, Venezuela, and Ecuador. Phylogenetic analysis was used to infer the relationships and times since the divergence of the major clades. RESULTS: Phylogenetic analyses revealed 2 dominant clades that segregated by geographical region, had a putative common ancestor in 1975, and originated in 1989, in North America, and in 1985, in South America. Emergence of these parallel epidemics coincides with the independent acquisition of the arginine catabolic mobile element (ACME) in North American isolates and a novel copper and mercury resistance (COMER) mobile element in South American isolates. CONCLUSIONS: Our results reveal the existence of 2 parallel USA300 epidemics that shared a recent common ancestor. The simultaneous rapid dissemination of these 2 epidemic clades suggests the presence of shared, potentially convergent adaptations that enhance fitness and ability to spread.