Atividade antimicrobiana in vitro de extratos hidroalcoólicos de <i>Psidium guajava</i> L. sobre bactérias gram-negativas

Abstract

Este estudio tiene como objetivo probar in vitro por los métodos de difusión en disco de papel las susceptibilidades de bacterias Gran-negativas (Escherichia Coli, Pseudomonas Aeruginosa, Shigella spp, Proteus spp, Klebsiella spp, Salmonella spp) a los extractos hidroalcohólicos de hojas y ramas de Psidium guajava (goiabeira vermelha) y determinar su CMI en medio sólido. Se verificó que, expeptuando Klebsiella spp, todas las bacterias testeadas fuero inhibidas por los dos extractos utilizados, siendo que los extractos de hoja presentaron menor actividad para la Salmonella spp (17,3mm) y los extractos de rama fueron mas activos para Proteus spp (18,3mm). La CMI varió de 1,8 a 2,4 mg/mL en extracto de hoja y de 1,2 a 2,4 mg/mL en el extracto de rama. Para la Shigella spp y Pseudomonas Aeruginosa, la CMI fue de 1,2/mL en el extracto de rama. No hubo diferencias estadísticamente significantes entre los dos tipos de extractos, tanto en los tets antimicrobianos como en los valores de CMI.

In vitro antimicrobial activity of hydro-alcoholic extracts of Psidium guajava L. against gram-negative bacteria. The aim of this study was to test in vitro by a standardized single disk method the susceptibility of gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella spp, Proteus spp, Klebsiella spp, Salmonella spp) in relation to hydro-alcoholic extracts of leaf and branch of Psidium guajava L. (known as goiabeira vermelha). A second aim was to determine the Minimum Inhibitory Concentration (MIC) in a solid medium. Except for Klebsiella spp, all tested bacteria were inhibited by both extracts. Leaf extract proved to be more active against Salmonella spp (17.3 mm) while branch extract showed better results against Proteus spp 18.3 mm). Minimum Inhibitory Concentration varied from 1.8 up to 2.4 mg/mL of leaf extract whereas for branch extract it varied from 1.2 up to 2.4 mg/mL. For Shigella spp and Pseudomonas aeruginosa MIC values were 1.2 mg/mL of branch extract. In general, no statistically significant differences were observed between both extracts when testing antimicrobial activity and MIC.