Synergistic Effects of Honeys and Commonly Used Antibiotics on Gram Positive Bacteria

Abstract

Searching for new antimicrobial agents are very interesting, especially after increasing bacterial resistance to commonly used antibiotics. This study aimed to investigate the growth inhibitory effect of sidr and sommor honeys and to evaluate the synergistic effects of various honey concentrations and five antibiotics on gram-positive bacteria in vitro using agar well diffusion and disk diffusion techniques. This is the first time for studying the antibacterial activity and synergistic effect of sommor honey against bacteria. The results indicated that sidr and sommor honeys had antibacterial activity against the clinical isolates and reference strains of S. aureus and Strept. pyogenes. The reference strains were more susceptible to sidr honey than sommor honey while the clinical isolates were more susceptible to sommor honey than sidr honey. The highest growth inhibitory effect was showed for 80% sommor honey concentration against Strept. pyogenes with IZD 35.33±0.33mm. Increasing honey concentrations either alone or in combination with antibiotics was significantly increased (P<0.05) the growth inhibition of the tested bacteria. The synergistic effects of honeys with antibiotics were significantly (P<0.05) different among the tested gram-positive bacteria. The highest synergistic effect was observed against Strept. pyogenes clinical isolate when sidr and sommor honeys combined with ofloxacin, pipracillin, amoxicillin + clavulanic acid and sulphamethoxazole + trimethoprim. Sidr and sommor honeys were effective antibacterial agents and can be used in combination with antibiotics for limitation of drug resistance and treatment of gram positive bacterial infections especially S. aureus and Strept. pyogenes.