The synergy between Sri Lankan bee honey and silver nanoparticles on pathogenic bacteria

Abstract

The study was to assess the antimicrobial activity of A1-silver-nanoparticles (A1AgNPs) in combination with Sri Lankan bee-honey (SLBH) on medically important Gram-negative and positive bacteria. The A1AgNPs were synthesized following the reduction of silver nitrates by sodium citrate. Using SLBH 20 % (v⁄v) stock solution, a dilution series from 1 % (v⁄v) intervals between 0 % and 10 % were made. The agar plates that contain A1AgNPs and SLBH were separately inoculated using bacterial suspension. Each organism's fractional inhibitory concentration index (ΣFIC) was calculated to assess the synergy. The minimum inhibitory concentration (MIC) of A1AgNPs for E. coli (6.7 ± 0.48), Shigella dysenteriae (6.66 ± 0.51), P. vulgaris (7.16 ± 0.4), P. aeruginosa (7.1 ± 0.33) and Salmonella Typhimurium (7.8 ± 0.83) were given in v/v%. Once the addition of equal volumes of A1AgNPs and SLBH, the spectrum of activity of the A1AgNPs improved from Gram-negative spectrum to Gram-positive, including MRSA (MIC 4.31 ± 0.47). Also, MIC values were further reduced, indicating a synergistic activity between the A1AgNPs and SLBH and E. coli, S. dysenteriae, P. vulgaris, P. aeruginosa, and Salmonella Typhimurium ΣFIC was 0.48, 0.48, 0.48, 0.48, and 0.44, respectively. In the future, SLBH can be used as a base for synthetic A1AgNPs to treat pathogenic bacteria.