| Congresso Brasileiro de Microbiologia 2023 | Resumo: 727-1 | ||||
Resumo:Methicillin-resistant Staphylococcus aureus (MRSA) is one of the main healthcare associated multidrug-resistant bacteria in the world. They are capable of forming biofilm, an important virulence factor that makes them difficult to combat, since they are protected from the immune system and antimicrobials action. Thus, given the serious infections caused and the lack of effective antimicrobials for treatment, antimicrobial alternatives capable of interfering in biofilm formation process have been sought. In this sense, polypyrrole is a promising synthetic polymer, which has been demonstrating potential activity against gram-positive and gram-negative bacteria, as well as yeast. Therefore, the aim was to evaluate polypyrrole antimicrobial activity, alone or in combination with oxacillin, and its antibiofilm effect on MRSA strains. For this, 10 clinical isolates of MRSA and strains of the American Type Culture Collection (ATCC) 25923 (sensitive to methicillin) and 33591 (resistant to methicillin) of S. aureus were used. Initially, the bacteria were cultivated in tryptic soy agar at 37 ºC for 24 h, they were used for the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of polypyrrole and oxacillin, through microdilution in broth method. The combinatorial effect between polypyrrole and oxacillin was evaluated using the checkerboard method. Bacteria biofilm production was quantified by the adherence to polyethylene microplates method, and staining with gentian violet. Additionally, the interference of different concentrations of polypyrrole was evaluated, both in the biofilm formation process (1/2 to 1/64 of the MIC) and in the consolidated biofilm (MIC value at 1/8 of the MIC). Polypyrrole showed antimicrobial activity against all samples, with inhibition between 62.5 to 125 μg/mL and bactericidal action at 62.5 μg/mL. For oxacillin, the inhibitory and bactericidal concentration ranged from 500 to 1,000 μg/mL. All samples showed a synergistic effect between polypyrrole and oxacillin, with emphasis on the resistance reversion observed for ATCC 33591. Regarding biofilm production, 100% of the isolates were able to produce this structure and were characterized as moderate (66 .67%) to strong (33.33%) producers. Polypyrrole interfered on biofilm formation process in 91.66% of the samples, changing its classification for non or weak producers, however, there was no interference for consolidated biofilm. Thus, it can be concluded that polypyrrole, in addition to presenting intrinsic activity against clinical isolates of MRSA, has a potential synergistic effect with oxacillin and an effect against the biofilm formation, bringing advantages for the treatment of infections caused by these multiresistant bacteria. Palavras-chave: antimicrobial polymer, biofilm, combination therapy, PPy Agência de fomento:Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES). Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco. HU-UNIVASF/EBSERH. | |||||