In vitro antimicrobial efficacy of two medical grade honey formulations against common high‐risk meticillin‐resistant staphylococci and Pseudomonas spp. pathogens

Abstract

Background Antimicrobial resistance is a problem in human and animal healthcare. Honey may be used for its wound healing properties and antimicrobial effects. Objective To investigate the antimicrobial activity of two commercially available medical grade honeys (MGHs) against Staphylococcus spp. and Pseudomonas spp. isolates. Methods and materials Two formulations, MGH1 (40% w/v honey) and MGH2 (80% w/v Manuka honey), were tested in vitro for minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) against 11 Staphylococcus and 11 Pseudomonas isolates at low [1.5 × 104 colony forming units (cfu)/well] and high (1.5 × 106 cfu/well) concentrations of inoculum, representing systemic and cutaneous bacterial loads during infection, respectively. Results MGH2 showed a lower MIC against staphylococci than MGH1, although this was not statistically significant. MGH1 had stronger bactericidal effects against staphylococci than MGH2, although this effect was statistically significant only at the higher bacterial concentration (P < 0.01). For Pseudomonas spp., MGH1 had significantly higher antimicrobial activity (both MIC and MBC) than MGH2 against all isolates tested and at both bacterial concentrations (P < 0.05). Conclusions and clinical importance Both MGHs were effective in vitro against common cutaneous pathogens including meticillin‐resistant staphylococci and Pseudomonas species. The higher efficacy of the MGH1 formulation against Pseudomonas and its consistent effects against staphylococci, while containing only half of the amount of honey compared to MGH2, invites further investigation of the mechanisms and clinical applications of MGH1.

Medical-Grade Honey Kills Antibiotic-Resistant Bacteria and Prevents Amputation in Diabetics with Infected Ulcers: A Prospective Case Series

“…A direct in vitro comparison study of L-Mesitran Soft and Medihoney against multiple (antibiotic-resistant) strains of staphylococci and Pseudomonas spp. pathogens showed that L-Mesitran had a more robust antimicrobial activity, despite containing half the concentration of honey [ 11 ]. This may have been caused by the difference in the type of honey, as there can be a 100-fold difference in antimicrobial activity between honey types [ 26 ]; alternatively, it may have been caused by the supplements added to L-Mesitran Soft [ 11 ].…”

“…pathogens showed that L-Mesitran had a more robust antimicrobial activity, despite containing half the concentration of honey [ 11 ]. This may have been caused by the difference in the type of honey, as there can be a 100-fold difference in antimicrobial activity between honey types [ 26 ]; alternatively, it may have been caused by the supplements added to L-Mesitran Soft [ 11 ]. Other studies demonstrated that L-Mesitran Soft has a stronger antimicrobial activity than its raw honey, which supports that the supplements added to the formulation, such as vitamins C and E, enhance the antimicrobial activity [ 11 , 12 , 13 ].…”

“…Since the antimicrobial activity of MGH is based on multiple mechanisms, microorganisms are not capable of developing resistance toward MGH [ 10 ]. Interestingly, smart honey formulations have added supplements such as vitamins C and E to further enhance the antimicrobial activity of raw honey [ 11 , 12 , 13 ]. MGH decreases the bacterial load, while it additionally prevents the invasion of new pathogens by forming a physical barrier when applied to the wound.…”

Treating severe wounds in pediatrics with medical grade honey: A case series

“…Several studies have demonstrated that the supplements in L-Mesitran enhance the antimicrobial properties of its raw honey 20,21 and is more potent than Manuka-based Medihoney. 22…”

Clinical Significance of Manuka and Medical-Grade Honey for Antibiotic-Resistant Infections: A Systematic Review

“…A range of inhibition can be observed for both Manuka honey and medical-grade honey against a variety of Staphylococcus aureus isolates, with all MICs being 20% or less [31][32][33]35,[37][38][39][40][41][42]45,46]. For Manuka honey, the Comvita Manuka 5+ exhibited the lowest MIC for almost all Manuka honey types tested against S. aureus ( Figure 1A).…”