Comparing the Antimicrobial Actions of Greek Honeys from the Island of Lemnos and Manuka Honey from New Zealand against Clinically Important Bacteria

Abstract

Honey is a natural food that has a long history as a traditional medicine because of its many biological characteristics, including antimicrobial, antioxidant, anti-tumor and anti-inflammatory properties. In this study, the antimicrobial actions of eight different honeys from Lemnos island (north-eastern Greece) plus manuka honey (from New Zealand, UMF 30+, licensed in many countries as topical medical preparation) were evaluated against ten clinically relevant bacteria, including five Gram-positive (Staphylococcus aureus, S. epidermidis, Enterococcus faecalis, Listeria monocytogenes and Bacillus cereus) and five Gram-negative (Salmonella enterica serovars Enteritidis and Typhimurium, Escherichia coli O157:H7, Vibrio parahaemolyticus and Pseudomonas aeruginosa). To achieve this, an agar-well diffusion assay measured the diameter of inhibition zones (mm) of two selected concentrations for each honey (25 and 12.5% v/v). The minimum inhibitory and bactericidal concentrations (MIC and MBC) of each sample were also calculated and compared against two representative bacterial species (S. Typhimurium and S. aureus) using microdilution and agar spot methods, respectively. The pH, water activity, and pollen-grain content of each honey were also determined. Results revealed that all the Lemnos honeys presented antibacterial action, which for some samples was superior to that of manuka, highlighting their potential for exploitation as natural antimicrobial systems for use in foods and medicine.

An In Vitro Study of Different Types of Greek Honey as Potential Natural Antimicrobials against Dental Caries and Other Oral Pathogenic Microorganisms. Case Study Simulation of Oral Cavity Conditions

“…The pH of honey is between 3.2 and 4.5 [26,27,38,70]. This acidity is low enough to inhibit the growth of most microorganisms of the ones tested here [26,27,38,[70][71][72]. Although statistically significant differences were observed among the pH values off the different honey types, it was not possible to conclude any positive (or negative) statistically significant effect of these differences on the antimicrobial action either in well diffusion experiments or in MIC estimates.…”

“…The second antimicrobial reason of honey is the pH values. The pH of honey is between 3.2 and 4.5 [26,27,38,70]. This acidity is low enough to inhibit the growth of most microorganisms of the ones tested here [26,27,38,[70][71][72].…”

“…Artificial honey was prepared by dissolving 3 g sucrose, 15 g maltose, 81 g D-fructose, and 67 g D-glucose in 34 mL sterile water and stored in sterile bottles (all sugars were supplied by Sigma-Aldrich) [20,37]. This dilution of sugars represents the proportions of the four predominant sugars in natural honey samples [38]. AM HEALTH Manuka Health MGO™550+ (25+) (Lower Hutt, New Zealand) was used as a positive control.…”

A Review on the Antimicrobial Effect of Honey on Salmonella and Listeria monocytogenes: Recent Studies

“…The study concluded that environmental conditions, flower species and geographical location of flower sources are responsible for the variability in the antimicrobial activity of honey. Gkoutzouvelidou et al, (2021) investigated an inquiry encompassing eight honey samples sourced from Lemnos Island, in addition to one Manuka honey sample. The objective was to assess their antimicrobial potential against Listeria monocytogenes bacteria.…”