Potential of Raw MANUKA Honey in Combating Gram-Negative Clinical Isolates

Abstract

Background: The global rise of antimicrobial resistance threatens the efficacy of conventional antibiotics, particularly against multidrug-resistant pathogens. Natural alternatives such as honey, especially Manuka honey, have shown promising antimicrobial properties. Objective: This study evaluated the antibacterial activity of raw Manuka honey against clinical isolates of Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae, and compared its efficacy to ciprofloxacin. Methods: A total of 150 clinical isolates were obtained from blood samples at Civil Hospital Karachi. Antibacterial activity of Manuka honey at various concentrations was assessed using agar well diffusion, broth micro dilution assays. Ciprofloxacin served as the reference antibiotic. Results: Manuka honey exhibited concentration-dependent antibacterial activity. Undiluted honey showed substantial inhibition zones: 24.6 mm for E. coli, 24 mm for P. aeruginosa, and 23 mm for K. pneumoniae. MIC and MBC values indicated E. coli was the most susceptible, with full inhibition and bactericidal effect at 80% concentration. P. aeruginosa and K. pneumoniae required 100% honey for complete inhibition and killing. Conclusion: Raw Manuka honey demonstrated broad-spectrum antibacterial activity, particularly against E. coli, and showed partial effectiveness against isolates of Klebsiella pneumoniae and Pseudomonas aeruginosa. These findings suggest its potential as a natural antimicrobial agent where high concentrations can be maintained.