Additive action of royal jelly and honey against Staphylococcus aureus.

Four varieties of honey and one variety of freshly reaped royal jelly (RJ) were used to evaluate their additive action against Staphylococcus aureus (ATCC 29523). In a first step honey and RJ were used separately to determine their minimum inhibitory concentration (MIC) against the tested strain. In a second step, lower concentrations of honey than the MIC were added to lower concentrations of RJ than the MIC and then incorporated into media to determine the minimum additive inhibitory concentration. When tested separately, the MIC of the four varieties of honey ranged between 20% and 21% (vol/vol), and that of RJ was 2% (vol/vol). When used jointly, all honey varieties had a more than 50% decrease in MIC with 1% (vol/vol) RJ. A strong linear correlation was noted between the MIC decrease of all varieties of honey and RJ.