Germicidal efficacy of disinfectant based on sodium hypochlorite and essential oils

The use of natural substances with antimicrobial activity in combination with conventional antimicrobial agents is a promising strategy in the control of pathogenic bacteria. The aim of this study was to examine the antimicrobial activity of a disinfectant based on sodium hypochlorite and lavender, tea tree, peppermint and rosemary essential oils against Gram-positive (Bacillus cereus ATCC 11778, Staphylococcus epidermidis ATCC 12228) and Gram-negative (Pseudomonas aeruginosa ATCC 10145, Salmonella Typhimurium ATCC 14028) bacteria. Further, to evaluate the antimicrobial activity of essential oils and the disinfectant mixed in various combinations in order to detect synergistic or antagonistic effects and discuss these effects on the basis of an improved checkerboard technique. The results showed a synergistic and additive effect for most combinations of the disinfectant and essential oils with fractional inhibitory concentrations index (FICI) values of 0.375 and 1, respectively. The effectiveness of the disinfectant in combination with essential oils was also determined using the quantitative suspension test and results indicated the maximum germicidal effect after the exposure time of 5 min. Taking into account increased interest in the use of natural antimicrobial agents in recent years, the application of a combination of disinfectant with essential oils represents a significant strategy in the control of pathogenic bacteria.