Oxidative stress in Staphylococcus aureus as a mechanism of action of silver nanoparticles phytosynthesized with Bothriochloa laguroides.

TORANZO A; LUCERO-ESTRADA, CECILIA S. M.; PAEZ PL

Virtual

Congreso; SAMIGE - SAIB 2020; 2020

Thelarge increase in bacterial strains resistant to currently used antibiotics emphasizes the need for new approaches to treating infections Because silver nanoparticles ( have demonstrated antimicrobial activity, the development of new applications in this fieldmakes them an attractive alternative to antimicrobials The AgNPs could generate a condition of oxidative stress in bacterial cells due to an increase in reactive oxygen species ( these species are capable of causing damage at the level of bacterial macromoleculeswhich would lead to their death In previous works we saw that phytosynthesized AgNPs with aqueous extract of Bothriochloa laguroides had activity against Staphylococcus aureus in both planktonic and sessile cells The objective of this work was to determine if AgNPsphytosynthesized from the aqueous extract of B laguroides produce oxidative stress with the consequent oxidation of macromolecules in two strains of S aureus The ROS were determined by using the probe 6 carboxy 2 7 dichlorodihydrofluorescein diacetatediacetoxymethyl ester (H 2 DCFDA), the oxidation of lipids was determined by a colorimetric technique that uses thiobarbituric acid which reacts with aldehydes that are produced by lipid peroxidation, protein oxidation was quantified by a colorimetric technique thatinvolves the use of potassium iodide which reacts with oxidized proteins All these determinations were carried out at different times 0 1 2 and 3 h) both for the untreated strains ( and for those treated with different concentrations of AgNPs For the S aureusstrain 43300 (methicillin resistant) the increase in ROS with respect to the control was seen since 1 h incubation with contractions of AgNPs equivalent to the MIC and the supraMIC Regarding the S aureus strain 29213 (methicillin sensitive), the increase at MIC andsupraMIC concentrations was also seen at the time of incubation, reaching a maximum at 3 h Strain 43300 treated with MIC and supraMIC of AgNPs showed an increase in protein oxidation from the hour of incubation, this increase was greater at supraMIC concentrations,the increase was maintained until 3 h of incubation In strain 29213 the same behavior was observed as in strain 43300 The highest oxidation of lipids in both strains was observed at 3 h of incubation with a concentration of AgNPs higher than the MIC In this work it wasshown that AgNPs are capable of producing oxidation of bacterial macromolecules, which could be the cause of their antibacterial activity