Ação cicatrizante e atividade antibacteriana a estirpes de Staphylococcus resistentes do extrato etanólico de Psidium guajava

Abstract

The use of medicinal plants is a human therapeutic resource dated years before the Christian era being the popular knowledge a vehicle for spreading the efficiency of such herbal medicines which will serve technological generations in the development of new low-cost drugs and lower residual impact. The objective of this research was to evaluate the antimicrobial activity and healing of Psidium guajava on strains of Staphylococcus. Four strains of Staphylococcus sciuri (SsI, SsII, SsIII and SsIV), one of Staphylococcus xylosus (Sx) as well as the control strain Staphylococcus aureus (Sa) were compared to the P. guajava extract and antibiotics. For infection control tests 20 Wistar mice were used, all males, separated into 4 groups of 5 mice each. The leaves of the plant were crushed to obtain the extract and 10, 50, 120, 210, 330, 400, 480, 530, 650 and 900 μL/ml treatments. Its toxicity was evaluated by DL-50. The resistance profile and antimicrobial activity were evaluated by the disk-diffusion method, the control of infection and healing were recorded after the subcutaneous application of the extract and the positive control (antibiotic). Only the treatments with 650 and 900 uL/mL were considered toxic with LD-50 values over 50%. All strains were sensitive to the extract with inhibition halos over 20 mm. They were considered to be resistant to oxacillin antibiotics and penicillin G strains SsII, Sx and SsIV and the immuno-histochemistry evaluation showed that in the groups of animals that received the extract as a treatment there was re-epithelialisation with denser collagen fibers as compared to other groups. Thus there is a great therapeutic potential of P. guajava as a promising natural resource for the development of more affordable drugs to the population and low residual impact.