Microcalorimetric investigation on the antimicrobial activity of honey of the stingless bee Trigona spp. and comparison of some parameters with those obtained with standard methods

The ever-increasing report of drug resistance by bacteria and side effects of certain pharmaceutical products are leading to aversion to some synthetic drugs and resurgence of the use of alternative therapies, such as apitherapy i.e. therapy with bee products. Honey of the stingless bee, Trigona spp., is used in Ethiopia as a panacea against dozens of ailments and considered to be superior to honeybee honey. The kinetics of antibacterial actions of two stingless bee honey samples obtained from Ethiopia were investigated using a flow calorimetric method. Four Gram-positive and two Gram-negative bacterial species were tested in vitro. The minimal inhibitory concentration (MIC) values from the calorimetric experiments were compared with those obtained from petridish and spectrophotometric methods. The calorimetric method displayed antimicrobial activities of weak honey concentrations that could not be detected with standard microbiological methods. Calorimetric results also indicated that lower concentrations of honey have bacteriostatic where as higher concentrations show bactericidal actions. The MIC values obtained from the calorimetric method were several folds lower than those from the petridish and spectrophotometric methods, showing the very high sensitivity of the former one. Both honey samples have broad-spectrum antimicrobial actions against both Gram-positive and Gram-negative bacteria.