| Congresso Brasileiro de Microbiologia 2023 | Resumo: 5-1 | ||||
Resumo:Proteus mirabilis is a well-known opportunistic pathogen in urinary tract infections, particularly in catheter-associated urinary tract infections, whose biofilm plays an important role in pathogenicity and persistence on the uroepithelium surface. Associated with biofilm production, increasing reports of multidrug-resistant (MDR), extended-spectrum &beta-lactamase (ESBL)-producing and carbapenem-resistant (CR) P. mirabilis uropathogenic strains have become a clinical concern. In the effort to mitigate this challenge, a potential solution relies on the use of silver nanoparticles (AgNP) as an alternative antimicrobial, especially synthesized by biological methods (or green synthesis) due to their low carbon footprint and no hazards production. Based on these data, this study aimed to biosynthesize AgNP using a commercial strain of Escherichia coli, characterize its properties, hemotoxic activity, antibacterial and antibiofilm activity against a MDR ESBL-producing CR P. mirabilis uropathogenic strain. For this purpose, AgNP biosynthesis was performed by adding an aqueous solution of AgNO3 to the cell-free supernatant of Escherichia coli ATCC® 25922™. AgNP formation, size, polydispersity index (PDI) and ζ-potential were determined by UV-VIS spectrophotometry, DLS and ELS technique. The hemolytic activity against human erythrocytes, CC50 value and selectivity index (SI) were quantified in order to assess human safety. MDR ESBL-producing meropenem-resistant P. mirabilis uropathogenic strain LBUEL-H1 was submitted to broth microdilution to determine the AgNP minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Ratio MBC:MIC was evaluated in order to classificate this AgNP as bactericidal or bacteriostatic. Biofilm inhibitory and destructive activity was evaluated at 1x, 2x and 4x MIC value and quantified through violet crystal staining method and MTT-reduction colorimetric assay, respectively. AgNP displayed absorbance peaks at 415 nm, average size of 100.2 nm, ζ-potential of -27 mV and PDI of 0.24, indicating its formation, nanometric nature, colloidal stability and monodispersity. Hemolytic activity at 6.6875 μg/mL, 13.375 μg/mL, 26.75 μg/mL, 53.5 μg/mL and 107 μg/mL were <0.0003%. The CC50 value was 535.01 μg/mL and SI >80, being possible to classificate this AgNP as both non-hemotoxic and bioselective. The MIC and MBC values against LBUEL-H1 were 6.6875 μg/mL and 13.375 μg/mL, respectively. The MBC:MIC ratio was 2, classifying this bioactive as bactericidal. Through crystal violet staining, it was observed that AgNP inhibited 8% of biofilm formation at 1x MIC and 100% at both 2x and 4x MIC concentrations. At the same concentrations, the MTT-reduction colorimetric assay revealed a decrease in biofilm cell viability by 81%, 84%, and 92%, suggesting that these AgNP were able to penetrate the mature biofilm, a naturally recalcitrant structure to antimicrobials diffusion. These results suggest that using E. coli ATCC® 25922™ cell-free supernatant as a reducing and stabilizing agent has the potential to produce stable AgNP with excellent antibacterial and antibiofilm activity, as well as high biocompatibility with human erythrocytes. Consequently, this data opens up new opportunities for biomedical applications in preventing or controlling the growth of multidrug-resistant bacterial pathogens.
Palavras-chave: Alternative antimicrobial, Hemotoxicity, Multidrug resistance, Nanobiotechnology Agência de fomento:Universidade Estadual de Londrina | |||||