Antimicrobial Activity of Litsea, Lemon and Rosemary Essential Oils and Their Combinations Against Healthcare and Sportswear Infection-Related Pathogens

Axillary odour, athlete’s foot, eczema and infected wounds, are all conditions that are caused by organisms such as Staphylococcus aureus, Staphylococcus epidermidis, Trichophyton rubrum, Escherichia coli and Pseudomonas aeruginosa. Antimicrobial textiles such as wound dressings if rendered antimicrobial may go some way in combating such diseases and it is becoming increasingly important to consider the environment when selecting consumer goods such as textiles, as problems such as toxicity and other health hazards have led to processing of textiles by more eco-friendly methods. Essential oils (EOs) are now being explored as natural antimicrobials (Kavanaugh and Ribbeck 2012). Ten EOs were screened by the disc diffusion method against S. aureus, P. aeruginosa, E. coli, S. epidermidis and T. rubrum. The Minimum Inhibitory Concentrations (MIC), Minimum Bactericidal Concentrations (MBC) and Fractional Inhibitory Concentrations (FICs) of Litsea, Lemon and Rosemary EOs were determined using the microdilution method. Litsea oil was most effective, with an average zone of inhibition (ZoI) of 47 mm, 20 mm, 53 mm, 43 mm and 90 mm (complete inhibition) against S. aureus, P. aeruginosa, E. coli, S. epidermidis and T. rubrum respectively. Lemon and Rosemary were the only other EOs effective against P. aeruginosa (ZoI 21 and 24 mm respectively), as well as inhibiting the other microorganisms. S. aureus was the most susceptible bacterial organism, being inhibited by all EOs tested; P. aeruginosa in turn was the most resistant. The MIC and MBC of Litsea, Lemon and Rosemary EOs (the most effective EOs against all tested organisms) were determined. Litsea EO gave the lowest MICs and MBCs against all microorganisms, ranging from 0.6-10.4 mg/ml and 1.2-20.8 mg/ml respectively. The organisms were least susceptible to Lemon EO with MIC and MBC concentrations of 10.1-40.4 mg/ml and 20.2-40.4 mg/ml respectively. Synergistic interactions between the 3 EOs were observed for E. coli only (FIC index = 0.5); for the other organisms, interactions were either antagonistic or antimicrobial but not synergistic. Essential oils are promising natural antimicrobials which can inhibit the growth of Gram-positive and Gram-negative bacteria as well as dermatophytes; and therefore, are good microencapsulation core material candidates for use in functional antimicrobial textiles that are eco-friendly and may effectively be used to alleviate skin conditions and malodour