| Congresso Brasileiro de Microbiologia 2023 | Resumo: 24-1 | ||||
Resumo:The Enterobacteriaceae family stands out clinically as opportunistic bacteria that have emerged as pathogens that cause Healthcare-associated Infections (HAI), which have mechanisms of resistance to beta-lactam antimicrobials. Previous studies have reported the possibility that oxidative stress is aligned with antimicrobial resistance. Microorganisms have an antioxidant protection system as a defense mechanism against free radicals. Free radicals whose unpaired electron is centered around oxygen atoms are called ROS (reactive oxygen species), which can originate from exogenous oxidizing agents such as menadione, which have the potential to increase oxygen levels in cells bacterian. ROS, which can cause cell death and inhibit the regeneration of reducing equivalents and compounds required for the activity of the regulon systems of Escherichia coli SoxRS which are composed of genes encoded by derived resistance products. This study aims to analyze whether Escherichia coli strains of clinical origin are resistant to beta-lactam antimicrobials induced via menadione. In the proposed experiment, cells were analyzed from overnight growth in Luria-Bertani (LB) medium. Twenty-six strains of the E. coli species of fecal (rectal swab) and urinary origin from clinical material were evaluated, based on samples from the Strains sector of the Bacteriology Laboratory (HUPE-UERJ). Strains of the wild species E. coli AB1157 and the triple mutant BW535 (xth-, nth- and nfo-) were selected under the action of menadione for evaluation of DNA repair and production of oxidative lesions in the repair pathways to base the excision of the damage oxidative (BER). For the experiment, all strains were cultivated in Luria-Bertani (LB) medium at 37°C with agitation at 150 rpm for 18h. After this first cultivation, a new sowing is carried out in LB medium at 37°C with agitation at 150 rpm until reaching the optimal density (OD) of 0.5 on the Mac Farland scale. Subsequently, the strains were supplemented with different concentrations of menadione (12.5, 25, 50, 100μM), added with 2 μL of CuCl2 at 5 μM and incubated for 30 minutes to evaluate DNA repair and the production of oxidative lesions. Then, the susceptibility profile to antimicrobial agents (AST) was determined, according to the Kirby Bauer method. When performing AST before menadione treatment, all strains tested were resistant to cephalothin (1st generation cephalosporin) and only one strain was resistant to ceftriaxone (3rd generation cephalosporin) and cefepime (4th generation cephalosporin), in addition to to be resistant to carbapenems. Preliminary results indicated that the bacterial strains tested with menadione at a lower concentration (12.5μM) had a reduced number of bacterial colonies. As it is a lipossoluble compound, it can alter the fluidity and modulate the permeability of the cell's plasmatic membrane. In enterobacteria, porins facilitate the entry of nutrients and other elements such as antimicrobials into the cell, causing the loss of functional porins, enabling resistance. It is concluded that the E. coli strains showed acquired resistance, response to oxidative stress induced by menadione and intrinsic resistance to certain beta-lactam antimicrobials used. Palavras-chave: Enterobacteriaceae , Menadione, Oxidative stress, Resistance Agência de fomento:Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro -FAPERJ | |||||