ANTIBACTERIAL ACTIVITY OF MEDICINAL PLANTS AGAINST MULTIDRUG-RESISTANT BACTERIA

The main cause of increasing of infectious diseases cases is due to multidrug-resistant microorganisms emergence, particularly Pseudomonas aeruginosa and Staphylococcus aureus, responsible for most of hospital-acquired infections and millions deaths related. Despite development of new antibiotics, control of these microorganisms is not always successful.  Several plant extracts have demonstrated antimicrobial effects and may be used as an alternative therapy for these infections. Aiming to evaluate antibacterial activity of extracts from Eleutherine plicata (marupazinho), Geissospermum vellosii (pau-pereira) and Portulaca pilosa (amor crescido) against multidrug-resistant bacteria, samples of Oxacillin-Resistant Staphylococcus aureus (ORSA) and multidrug-resistant P. aeruginosa (MDR P. aeruginosa) isolated from human clinical processes were tested. The antibacterial activity was determined by disk diffusion method and minimum inhibitory concentration (MIC) by microdilution method.  Extracts and fractions were tested at concentrations of 500, 250, 125, 62.5, 31.2 and 16.2 µg/mL dissolved in DMSO 10%. E. plicata and G. vellossi have shown activity against ORSA at MIC of 125 µg/L, whilst P. pilosa have shown action on MDR P. aeruginosa at MIC of 250 µg/mL. Results suggest the extracts of E. plicata, G. velossi and P. pilosa have antimicrobial activity with potential use as phytoterapic drugs or for further research on new antimicrobial drugs.