Evaluation of the Antibacterial Activity of Extracts of Betula Pendula (Silver Birch) Bark Against Uropathogenic Microorganisms

Abstract

The aim of this work was to evaluate the antibacterial activity of the aqueous and ethanolic extracts of Betula pendula (silver birch) bark against various microorganisms causing urinary tract infections.Material and methods. Aqueous and ethanol extracts of biologically active compounds from Betula pendula bark were tested against ten clinical uropathogenic strains (gram-positive bacteria — Kocuria rhizophila 1542, Staphylococcus simulans 5882, Enterococcus avium 1669, Enterococcus faecalis 5960, and Corynebacterium spp. 1638; gram-negative bacteria — Enterococcus cloacae, Morganella morganii 6392, Escherichia coli 1449, Seratia mansescens 6441, and Achromobacter xylosoxidans 4892). Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 25922 were used as reference standards for Gram-positive and Gram-negative microorganisms. The sensitivity of the experimental strains to the antibiotic was evaluated by the Kirby–Bauer disk diffusion method, while the antibacterial activity of the obtained extracts was evaluated using the agar diffusion method. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were also determined via the serial dilution method.Results. The bark of B.pendula contained 78.85% of dry matter. The volume yield of the aqueous (AE) and ethanol extract (EE) was 74.66% and 86.66% (v/v), respectively, while their mass yields were 6.59% and 10.65% (w/w). K.rizophilia 1542 and Corynebacterium spp. 1638 were the most resistant bacteria with a multidrug resistance index of 0.45. AE and EE were active against all microorganisms tested. MIC of AE ranged from 8 to 32 mg/ml, while MIC of EE ranged from 2 to 16 mg/ml.Conclusion. An aqueous extract of Betula pendula bark exhibits weak antimicrobial activity, while the ethanol extract exhibits a more pronounced antimicrobial activity, but has a bacteriostatic effect.