Antibacterial Interactions between Two Monofloral Honeys and Topical Antiseptics, Including Essential Oils
Honey has long been recognized for its antibacterial properties and its potential as a treatment for superficial bacterial infections. However, little is known about how honey interacts with other topically applied antibacterial agents, such as antiseptics or essential oils. In this study, the authors investigated the interactions between two types of monofloral honey (marri and manuka) and several antiseptic agents, including benzalkonium chloride, chlorhexidine digluconate, silver nitrate, tea tree oil, and eucalyptus oil. The authors performed checkerboard assays and calculated fractional inhibitory concentration indices (FICIs) to determine the interactions between the honey and the antiseptics.
The authors prepared solutions of marri honey, manuka honey, and each antiseptic agent at different concentrations. They inoculated the wells of a microtitre plate with two strains of bacteria, ATCC® 43300 and ATCC® 27853, and incubated the plates for 24 hours. They visually inspected the plates and determined the minimum inhibitory concentration (MIC) for each combination of honey and antiseptic. They also measured the optical density of each well to quantify bacterial growth.
The authors found that most combinations of honey and antiseptic had additive or indifferent interactions, with FICI values ranging from 0.5 to 2. However, they observed an antagonistic relationship between chlorhexidine digluconate and both marri honey and manuka honey. They also found that tea tree oil combined with marri honey had a synergistic effect against one of the bacterial strains. Time-kill studies confirmed the antibacterial activity of the honey-antiseptic combinations.
These findings suggest that honey does not interfere with the antimicrobial activity of most topically applied antiseptics. However, there may be an antagonistic effect between honey and chlorhexidine digluconate. The authors speculate that this antagonism may be due to the complex and multifactorial mechanisms of action of both honey and chlorhexidine digluconate. Further research is needed to understand the specific mechanisms of these interactions and to determine their clinical relevance.
In conclusion, this study demonstrates that honey has additive or indifferent interactions with most topically applied antiseptics, indicating that honey may be suitable for combination therapy with these agents for the treatment of superficial bacterial infections. However, caution should be taken when combining honey with chlorhexidine digluconate, as an antagonistic effect was observed. Further research is needed to fully elucidate the mechanisms of these interactions and to explore the potential benefits of combination therapy with honey and antiseptics.
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