In vitro effects of Eugenia pyriformis Cambess., Myrtaceae: Antimicrobial activity and synergistic interactions with Vancomycin and Fluconazole

The Eugenia pyriformis Cambess. species, Myrtaceae, also known by the popular name as uvaia was evaluated for its antimicrobial activity. Broth microdilution method was used to determine the Minimum Inhibitory Concentration (MIC) against selected pathogenic strains of bacteria, and fungi. Checkerboard method was used to evaluate the synergistic interactions of E. pyriformis with Vancomycin and Fluconazole. The leaf and stem crude extract showed for Gram-positive strains MIC values of 125 and 250 µg/ml and for leveduriform fungi MIC values ranging from 7.81 to 62.5 µg/ml. Ethyl acetate, hydroalcoholic fractions, and leaf acetonic extract showed MIC values between 62.5 and 125 µg/ml for Gram-positive strains. The ethyl acetate fraction and leaf acetonic extract showed MIC values ranging from 7.81 to 62.5 µg/ml for leveduriform fungi; the stem acetonic extract MIC value was 62.5 µg/ml against Gram-positive strains and MIC value of 7.81 µg/ml for leveduriform fungi. The combination of E. pyriformis with Vancomycin and Fluconazole showed synergistic activity for strains of Enterococcus faecalis, Candida albicans, Candida krusei and Candida parapsilosis with fractional inhibitory concentration indices (FICI) below of 0.5. The extracts and fractions of this medicinal plant were able to inhibit the growth of bacteria and fungi in vitro.   Key words: Eugenia pyriformis Cambess, antimicrobial activity, synergistic interaction.