| Congresso Brasileiro de Microbiologia 2023 | Resumo: 866-1 | ||||
Resumo:Gram-negative bacilli, both enterobacteria and non-fermenters, are the main responsible for infections in snakes. The bacterial isolates from snake infections may exhibit a multidrug resistance profile through β-lactamases production and biofilm-forming ability, as well as other mechanisms. Silver nanoparticles have already been proven in the literature as having antimicrobial activity and antibiofilm formation, due to chemical, physical and biological
changes and their volume-surface relationship. This study was carried out to determine antimicrobial susceptibility pattern and biofilm formation of 37 bacterial strains isolated from snakes with pathologies, including Alcaligenes xylosidans, Escherichia coli, Enterobacter cloacae, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus vulgaris, Providencia rettgeri, Pseudomonas aeruginosa, Aeromonas hydrophilia, Stenotrophomonas maltophilia, Burkholderia cepacea, Ochrobactrum antrhropi, Delftia acidovorans and Acinetobacter junii as well as the antimicrobial activities of silver nanoparticles (Np McAg 5;2) against twelve strains. The strains were tested with the disc diffusion method (Kirby-Bauer)
and representative isolates were subjected to the disk-approximation test with antibiotics. The biofilm formation was verified by through crystal violet assay and was quantified using ELISA plate reader at 595 nm. The antimicrobial and antibiofilm activities of silver nanoparticles were
investigated. The isolates showed high sensitivity to Aztreonam, Ceftazedime, Cefepime, Ertapenem, Gentamicin and Levofloxacin (72.9% to 97.22%), with lower susceptibility to Imipinem, Cefotaxin and Tetracycline (56.75% to 65.16%). Five strains (13.5%) showed multidrug resistance and 91.67% of the selected twelve tested clinical strains were producers of extended spectrum β-lactamase. Nine strains (28.13%) showed intermediary biofilm formation (OD with values between 0.598 and 0.961) and nine strains showed a superior potential (1.002 to 2.276). Five strains treated with silver nanoparticles diluted twenty times showed 74.32% to 92.78% of growth inhibition and 36.94% to 100% of biofilm formation
inhibition at a dilution of eighty times. These results demonstrated the variation in the pattern of resistance, ranging from a high level of sensitivity to multidrug-resistant strains. Biofilm formation capacity is an important factor for bacterial persistence in the host, in the environment and for resistance to antibiotics. We concluded that monitoring antibiotic resistance provides data for more appropriate antibiotic therapy and resistance control in
infections caused by Gram-negative bacilli. Furthermore, silver nanoparticles were effective in inducing bacterial death and inhibiting biofilm formation in most of the tested strains, proving to be an important treatment alternative to be studied. Palavras-chave: Antimicrobial, Biofilm, Gram-negative, Nanoparticles, Silver Agência de fomento:Fundação Butantan, FAPESP | |||||