Anais do Congresso Paranaense de Microbiologia
IV Congress of Microbiology in Paraná

Enterococcus faecium is a Gram-positive bacterium, member of the gastrointestinal microbiota of healthy humans. In the last decades, this microorganism has been emerged as an important agent of healthcare infections (HAI), mainly due to the resistance to several antimicrobials. Biofilm formation is related to resistance to antimicrobials and environmental stresses, contributing to the persistence of microorganisms in different surfaces, including human host. Thus, the search and development of new substances with antimicrobial activity and low toxicity have been a major challenge for both researchers and pharmaceutical industry. Therefore, the aim of this study was to evaluate the in vitro activity of the oil-resin extracted from Copaifera martii against planktonic and sessile cells of vancomycin-resistant E. faecium (VREfm). The activity of C. martii oil on growth of planktonic VREfm cells was evaluated by minimum inhibitory concentration (MIC) determined by the broth microdilution method. VREfm established biofilm was treated with different concentrations of copaiba oil (1.0 – 0.03 mg/mL) and the metabolic activity of sessile cells were quantified by XTT-reduction assay after 24 hours of treatment. The oil-resin was able to inhibit planktonic and sessile cells growth of VREfm isolates and the reference strain E. faecium ATCC 6569. The minimum inhibitory concentration for planktonic cells was 0.06 mg / mL for all tested bacteria. After 24 hours of incubation in the presence of MIC, no colony forming unit was detected in any time-kill assay, indicating a bactericidal effect. In addition, reduction percentages from 35 to 83% and 80 to 99% in viability of VREfm sessile cells in the presence of MIC and 2 X MIC of copaiba oil were observed. Furthermore, the cytotoxicity of copaiba oil was tested in LLC-MK2 cells that was treated with different concentrations of copaiba oil (1.0 – 0.03 mg/mL). Only at the concentration of 0.5 mg/ml of copaiba oil there was 100% inhibition of cell viability, showing higher toxicity to VREfm strains. This study reports the antimicrobial activity of C. martii oil-resin on VREfm, indicating the potential to develop new control strategies for the infections caused by these bacteria.