| Congresso Brasileiro de Microbiologia 2023 | Resumo: 510-1 | ||||
Resumo:In recent years, the spread of pathogenic microorganism resistance to antimicrobial agents has created serious problems for public health. Among these pathogens, we can mention some species of Enterococcus, which, although many of them being commensals, can also act as opportunistic pathogens in some specific cases. Nosocomial infections by these bacteria are also frequently reported. The acquisition of virulence factors, resistance to antibiotics and ability to translocate from the gastrointestinal tract to other tissues and organs are factors that make the treatments frequently unsuccessful. Considering the antimicrobial potential of biogenic silver nanoparticles (AgNPs), the aim of this study was to evaluate the activity of these compounds on Enterococcus faecalis and Enterococcus faecium, as well as on their biofilms. Silver nanoparticles were synthesized using Fusarium oxysporum biomass, with an average size of 22 nm. Reference strains (two of E. faecalis and one of E. faecium) and clinical isolates (six of E. faecalis and three of E. faecium) were submitted to sensitivity tests to AgNPs through broth microdilution assays. The minimum inhibitory concentrations (MIC100) and minimum bactericidal concentrations (MBC100) were then determined, being characterized by the capability of inhibiting 100% of the bacterial growth or microbial inactivation, respectively. The inhibitory activity of AgNPs on biofilm formation and on the disruption of consolidated biofilms were also evaluated. Scanning electron microscopy (SEM) was used to observe morphological changes after the treatment with the AgNPs. The biogenic nanoparticles showed 100% bacteriostatic effect for all reference strains and clinical isolates, with the exception of one clinical isolate of E. faecium, at concentrations ranging from 31.25 to 125 ug/mL. Regarding the bactericidal effect, only two strains of E. faecium were not 100% inactivated by AgNPs. All reference strains and clinical isolates analyzed were moderate biofilm producers. AgNPs were able to interfere with the formation of biofilm by Enterococcus, with a maximum of 55% interference for E. faecalis, and 40% for E. faecium. In the consolidated biofilm, interference levels ranged from 20 to 40% for both species, respectively. SEM analyzes proved the antibacterial activity of AgNPs through significant morphological changes in the treated bacteria. Thus, AgNPs proved to be an antimicrobial agent with significant bacteriostatic and bactericidal activity on reference strains and clinical isolates of E. faecalis and E. faecium, as well as showing inhibition of biofilm formation and disruption of formed biofilm. These results may support the development of new antimicrobial drugs based on AgNPs. Palavras-chave: Antimicrobials, Microbial biofilm, Nanomaterials, Nanotechnology Agência de fomento:Fundação de Amparo à Pesquisa e Extensão (FAPEX) | |||||