Antimicrobial Activity of L. Extract on Pathogenic Bacteria Isolated from Otitis Externa of Dogs.

The present study investigated the antimicrobial activity, total phenolic content, and proanthocyanidin concentration of ethanolic extracts from fresh leaves of L. The extracts were phytochemically analyzed and evaluated for antimicrobial activity. The broth microdilution method was used to assess antimicrobial activity against pathogenic bacteria isolated from ear swabs taken from dogs with otitis externa. Many compounds were present in the ethanolic aqueous extracts, which exhibited a broad spectrum of antimicrobial activity. They showed strong antibacterial activity against standard clinical Gram-positive strains such as and Gram-negative strains such as . In our study, the obtained quantity of total phenolic compounds in the ethanol:water extract of leaves was 126.17 mg GAE/g. The proanthocyanidin concentration in the tested L. extracts was 15.39 mg PAC/g material. The high contents of total phenolics and proanthocyanidin indicated that these compounds contribute to antimicrobial activity. The antimicrobial activity of the tested L. extracts ranged from 1.47 to 63.75 µg/mL, starting with 1.47 µg/mL and 1.75 µg/mL against ATCC 25923 and ATCC 27853 strains, respectively. Likewise, L. ethanol extract demonstrated a bacteriostatic effect against clinical isolate with a median MIC of 23.25 µg/mL and MBC of 37.23 µg/mL; and bactericidal against ATCC 25923 with the median MIC of 20.33 µg/mL and MBC of 37.29 µg/mL. In the Gram-negative clinical and standard strains, the expressed MIC and MBC values were 24.234 and 20.53 µg/mL for MIC, and 37.30 and 37.02 µg/mL for MBC, respectively.