Antimicrobial properties of local Kelulut honey against selected oral pathogens

There are limited reports on the antimicrobial properties of Kelulut honey against oral pathogens. Hence, this study aimed to determine the antimicrobial properties of local Kelulut honeys obtained from the Malaysian Agriculture Research and Development Institute (MARDI) and Tangkak, Johor, Malaysia. The samples were mixed with sterile deionised water to obtain series of honey concentrations and evaluated against Streptococcus mutans, Staphylococcus aureus, Candida albicans and Candida tropicalis using agar well diffusion method. Bacteria S. mutans and S. aureus were grown anaerobically on Mueller-Hinton agar and incubated at 37°C for 24 hours, while fungi, C. albicans and C. tropicalis were grown on Sabouraud Dextrose agar at 25°C for 48 hours. Cultures were prepared in triplicates and adjusted to 0.5 McFarland standard (1 x 108 CFU/ml). Wells (6 mm diameter) were made on the agar, and 60 µl of honey at concentrations of 2.5, 2.0, 1.5, 1.0 and 0.75 g/ml were added onto each well. Sterile deionised water was used as negative control, and 0.2% chlorhexidine as positive control. Upon incubation, the zones of inhibition were measured using a digital calliper. Both Kelulut honeys exhibited zones of inhibition against S. mutans at 2.5, 2.0 and 1.5 g/ml whereas for S. aureus, the inhibition was noticed only at 2.5 and 2.0 g/ml. No inhibition zones were observed against C. albicans and C. tropicalis at any concentration. This study showed that both Kelulut honeys exhibited antibacterial properties against S. mutans and S. aureus but did not exhibit antifungal activity against C. albicans and C. tropicalis.