Pharmaceutica Analytica Acta

Abstract

Comparative Antimicrobial Activity of Tea Tree Oil (Melaleuca Oil) and Common Topical Antimicrobials against Bacteria Associated With Wound and Topical Infections

Bhoj R Singh, Prasanna Vadhana, Monika Bhardwaj, Vinodh Kumar OR, Dharmendra K Sinha and Shiv Varan Singh

Tea Tree Oil (TTO) is a popular herbal antimicrobial for topical application against many microbes. This study was conducted to determine a spectrum of antimicrobial activity of TTO against bacteria often associated with topical infections and wound infection in human and animals. A total of 550 strains of bacteria and one strain of Candida albicans were tested for their sensitivity to TTO and eight antibiotics including polymyxin B sulfate, gentamicin, nitrofurantoin, tetracycline, chloramphenicol, co-trimoxazole, ciprofloxacin, and novobiocin. Gentamicin was the most effective antibiotic followed by chloramphenicol, ciprofloxacin, nitrofurantoin and polymyxin B inhibiting 87.1%, 84.8%, 76.8%, 75% and 72.8% strains, respectively. Tea tree oil (at 1 μL/ mL) could inhibit the growth of 20.5% strains. Except all strains of Streptobacillus, Sphingomonas, Cytophaga and Brahmnella, 71.4% Brucella, 60% Bordetella and 53.1% Aeromonas species (46.9%), only a few strains of other genera were sensitive to TTO. Only 20.5% strains were sensitive to TTO and multiple drug resistance (MDR) was positively correlated to their resistance to TTO, as 50%, 25%, 12%, 6% and 5% of the strains resistant to 0, 1-2, 3-4, 5-6 and 7-8 antimicrobial drugs, respectively were sensitive to TTO. Sensitivity of bacteria to TTO was positively correlated (p, ≤0.05) with their sensitivity to novobiocin (r, 0.24), tetracycline (r, 0.22), gentamicin (r, 0.21), ciprofloxacin (r, 0.17), nitrofurantoin (r, 0.16), and chloramphenicol (r, 0.14) while correlation was insignificant (p, >0.05) with sensitivity to co-trimoxazole (r, 0.10) and polymyxin B (r, 0.12). Minimum inhibitory concentration (MIC) of TTO varied from 0.001% to >0.512% (v/v) for different strains. The study revealed that TTO is a broad-spectrum antimicrobial active on 26 out of 44 genera of bacteria is a less promising antimicrobial than antibiotics on MDR strains. The study concluded that resistance to TTO, antibiotics and other antimicrobials in bacteria of clinical origin go hand in hand.