Antibacterial activity and mechanism of action of some Iranian honeys compared to manuka honey against multidrug-resistant respiratory and urinary infections

Abstract

Increasing antibiotic resistance among bacterial pathogens requires the identification of alternative therapeutic agents, especially the natural ones. The importance of honey in health care was document from the oldest medical literature. Currently, the antimicrobial properties of honey, especially for the prevention of resistant strains, has been considered. However, from mechanistic insights, this activity has received less attention. In this study, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of 6 Iranian honey samples in comparison with Manuka honey against reference strains of Staphylococcus aureus ATCC 29737, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumonia ATCC 10031, Escherichia coli ATCC 10536 and 22 multidrug-resistant clinical strains of respiratory and urinary infections were determined. The survival of bacteria and their ability to produce biofilm in the presence of a bactericidal concentration of honey were monitored. The effect of the most powerful honey and Manuka on the structure of reference strains of the Staphylococcus aureus and Pseudomonas aeruginosa was investigated using Field Emission Scanning Electron Microscopy (FESEM) and flow cytometry analysis. Exposure of bacteria to the studied honey generally resulted in high antimicrobial and anti-biofilm activity of Iranian honey compared to Manuka honey. Using SEM, division inhibition accompanied by loss of structure and marked changes in cell shape and surface were observed in the presence of honey. Analysis of flow cytometric charts revealed synchronous increasing and decreasing in the size of honey-treated strains. Present results indicated that Iranian honey samples possess the potential to be an effective inhibitor of multi-drug resistant strains.