Potencial antibacteriano de nanopartículas de prata associadas ou não a quitosana e às drogas antimicrobianas

Abstract

Silver is known for its antibacterial activity and has been shown to be effective as a potential alternative in the context of bacterial resistance to drugs, particularly in the form of nanoparticles (AgNPs). Our objectives were to evaluate the susceptibility of bacteria against AgNPs and representative survey of synergistic or antagonistic when combined with chitosan (QIT) and antimicrobials for human therapeutic use. A total of eight reference strains were evaluated of Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, S. epidermidis and Enterococcus faecalis. The susceptibility patterns were determined by broth microdilution method, according to the CLSI guidelines. The minimum inhibitory concentration (MIC90) of AgNPS to the samples tested was 64μg/mL, while for the combination AgNPs-QIT was 16μg/mL. Considering only antimicrobial activity of QIT, the MIC90 was 16 mg / mL. Among the antimicrobials (meropenem, amikacin, gentamicin, levofloxacin, rifampicin, sulfamethoxazole- trimethoprim, tetracycline, and vancomycin and oxacillin, these only to Gram positive), while the MIC for each bacterial strain is in accordance to the reference CLSI, significant decrease was observed for all tested drugs when combined with AgNPs-QIT. In general, association of AgNPs with QIT or with antimicrobial drugs showed higher inhibitory potential, which may be related to the stability of the polymer associated AgNPs or positive interaction of nanoparticles with antibiotics. The Checkerboard assay was then performed to establish antagonistic or synergistic effects in each combination. The possibility of interaction of AgNPs and QIT with existing antimicrobials is highly relevant and reinforces the recommendations of the literature on the reformulation of traditional antimicrobial use, as well as research into new drugs and strategies to overcome the growing phenomenon of bacterial resistance to antimicrobials.