| Congresso Brasileiro de Microbiologia 2023 | Resumo: 323-2 | ||||
Resumo:Colistin has been used as a last-line antimicrobial agent against infections caused mainly by multidrug-resistant pathogens. However, the increase of colistin resistance, especially those mediated by plasmids, has been noted in the last few years, raising concerns. The environment plays a key role in the evolution of antimicrobial resistance, serving as a reservoir and disseminator of clinically important multidrug-resistant (MDR) bacterial strains, including Escherichia coli. Therefore, we obtained and characterized mcr-1-carrying E. coli strains from surface waters and agricultural soils of Brazil. Between 2020 and 2022, E. coli strains were isolated from waters and soils using MacConkey agar supplemented with colistin (2 mg/L). These strains were screened for mcr-1 to mcr-10 genes and 21 of them (14 from waters and seven for soils) were positive for the mcr-1 gene. In addition to colistin resistance (MIC 4 to 8 mg/L), mcr-1-positive E. coli strains were also MDR, highlighting the resistance to extended-spectrum cephalosporins and fluoroquinolones. In this regard, four representative mcr-1-producing E. coli strains (two from waters and two from soils) were submitted to whole-genome sequencing using the Illumina MiSeq platform. Genomic analyzes were performed to determine epidemiologic typing, virulome, resistome, and plasmidome. Various sequence types (ST) were identified, highlighting the presence of international high-risk clones (e.g., ST10). Virulome analysis mainly showed genes related to adhesion, invasion, colonization, and siderophores. In addition to mcr-1.1 gene, E. coli strains also carried acquired antimicrobial resistance genes to β-lactams, fluoroquinolones, aminoglycosides, tetracyclines, folate pathway inhibitors, and phenicols. Mutations in the quinolone resistance determining regions of GyrA, ParC, and ParE were identified in fluoroquinolone-resistant E. coli strains. Several plasmid incompatibility (Inc) groups were detected, spotlighting those carrying the mcr-1.1 gene (i.e., IncX4 and IncI2). The plasmid sequences showed high nucleotide identity with others distributed worldwide at the human-animal-environment interface. Therefore, our results demonstrate the occurrence of the plasmid-mediated mcr-1 gene, as well as the coexistence of mcr-1 and blaCTX-M genes in E. coli strains from the Brazilian environmental sector. Palavras-chave: Environmental contamination, mcr-1, plasmid, soil, water Agência de fomento:This study was supported by FAPESP (2021/01655-7), CAPES (88887.519091/2020-00, 8887.824722/2023-00, and Finance Code 001), and CNPq (304905/2022-4, 308914/2019-8, 130086/2021-5, 141016/2021-3, and 150712/2022-7). | |||||