Potencial antimicrobiano de complexos de cobre em Campylobacter jejuni

Abstract

Campylobacter jejuni is the most important pathogen involved in foodborne gastroenteritis worldwide. Their control becomes more difficult with the accentuated increase in antimicrobial resistance and acquisition of sessile form. It is known that development of new antibacterial agents has not kept up with the development of bacterial resistance mechanisms, which demands intense research for products with new action mechanisms that are not recognized by the bacteria. Currently, studies have demonstrated the high efficacy of copper (Cu) complexes in the treatment of cancer cells and as a new antimicrobial strategy. Thus, our study aimed to evaluate the efficacy of two types of copper complexes ([Cu(BTA)(Phen)ClO4] and [Cu(BTA)(Phen)NO3]), generically called CBP-01 and CBP-02, as a biocidal agent for free and sessile forms in C. jejuni, and to determine the Minimum Inhibitory Concentration (MIC) of the compound necessary to eliminate the pathogen. Fourteen strains of C. jejuni, isolated by the Ministry of Agriculture, Livestock and Supply (2017), were tested under the action of copper compounds in free and sessile forms by the MIC technique and visualized in Scanning Electron Microscopy (SEM) for ultrastructural analysis. All strains were susceptible to the action of the compounds, and the MIC determined for the planktonic form was lower when compared to the sessile form, with strain dependent values. For the complex CBP-01, the planctonic form was inhibited with an average concentration of 13.02 μM, while the sessile form required a higher concentration, average 107.5 μM. For compound CBP-02, the inhibitory concentration required for the planktonic form was 196.9 μM, significantly higher than that required for compound CBP-01 in the same form, and 259.4 μM for the sessile form. For CBP 01, 10/14 were controlled at values lower than 200 μM and 6/14 were inhibited at concentration equivalent to 400 μM with CBP-02. On SEM, biofilms treated with the CBP-01 compound at concentrations 100 and 400 μM showed signs of cell apoptosis or disintegration, matrix degeneration, absence of pores and bacterial exposure, most evident at the highest concentration tested. Overall, CBP-01 (perchlorate) showed higher efficacy, but both synthesized complexes showed good antibacterial activity and high susceptibility to the planktonic form and are therefore promising candidates for use in the control of C. jejuni in the medical and veterinary fields.