Antimicrobial activity of honey from the stingless bee Trigona carbonaria determined by agar diffusion, agar dilution, broth microdilution and time-kill methodology

Aims: The aim of this study was to determine the spectrum of antimicrobial activity of 11 samples of stingless bee honey compared to medicinal, table and artificial honeys. Methods and Results: Activity was assessed by agar diffusion, agar dilution, broth microdilution and time-kill viability assays. By agar dilution, minimum inhibitory concentration (MIC) ranges were 4% to > 10% (w/v) for Gram-positive bacteria, 6% to > 16% (w/v) for Gram-negative bacteria and 6% to > 10% (w/v) for Candida spp. By broth microdilution, all organisms with the exception of Candida albicans and Candida glabrata were inhibited at < 32% (w/v). Geometric MIC (w/v) means for stingless bee honeys ranged from 7 center dot 1% to 16 center dot 0% and were 11 center dot 7% for medicinal honey and 26 center dot 5% for table honey. Treatment of organisms with 20% (w/v) stingless bee honey for 60 min resulted in decreases of 1-3 log for Staphylococcus aureus, > 3 log for Pseudomonas aeruginosa and < 1 log for C. albicans. Similar treatment with each control honey resulted in decreases of < 1 log for all organisms. Conclusions: Stingless bee honey has broad-spectrum antibacterial activity although activity against Candida was limited. Stingless bee honey samples varied in activity and the basis for this remains to be determined. Significance and Impact of the Study: Stingless bee honey had similar activity to medicinal honey and may therefore have a role as a medicinal agent.