Atividade antimicrobiana de calcogenoésteres contra células planctônicas e biofilmes de Staphylococcus spp.

Abstract

Biofilms are described as microbial communities adhered to a surface and inserted into an extracellular polymeric matrix produced by themselves, being associated with increased antimicr obial resistance. Faced with this problem, the discovery of new molecules that have an antimicrobial effect is essential to overcome the current problems of antibiotic resistance. Thus, the aim of the present study was to evaluate the effect of compounds f rom the class of organochalcogens, the chalcogenoesters (selenoesters), on planktonic cells and biofilm of Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis ATCC 12228; the compounds were named S501, N1 and N2. To determine the antibacterial activity, the compounds were diluted in concentrations ranging from 250 to 7.8 μ g/mL and distributed in 96 well polystyrene plates, with each bacterial suspension adjusted (1 x 10 6 CFU/mL) in TSB medium, then incubated for 24 hours at 37°C. The susceptibil ity of the microorganism to the compounds was evaluated using minimal inhibitory concentration (MIC) and minimal bactericidal concentration (CBM) tests. The antibiofilm activity was evaluated by biomass quantification using the crystal violet staining meth od and by quantifying the number of viable cells in the biofilm by counting colony forming units (CFU). The results showed that S501, N1 and N2 presented MIC of 62.5, 125 and 62.5 μ g/mL, respectively, for S. aureus , whereas S501 and N1 presented MIC of 62.50, 125 μ g/m L , respectively, for S. epidermidis . All compounds inhibited the formation of biomass, standing out S501 and N1 that reduced about 80%. In addition, the number of viable cells in the biofilm was reduced, standing out S501 that at the concentration of 250 μ g/mL generated a reduction of 1.6 log 10 when compared to the control. Therefore, it is concluded that the tested chalcogenoesters may represent a potential alternative f or the prevention of biofilms involving S. aureus and S. epidermidis , however, further studies are needed to clarify the mechanisms of action of the studied compounds.