Antimicrobial activity of Malaysian Heterotrigona itama propolis against Enterococcus faecalis ATCC 4082: A study in endodontic applications

Abstract

Aims: The antimicrobial properties of Malaysian propolis towards Enterococcus faecalis (EF), the most prevalent pathogen in failed endodontics remained obscure. Moreover, methods in oral-propolis research, particularly in selecting the optimal antimicrobial susceptibility test, are still not standardised. This study was aimed to assess the Heterotrigona itama (HI) propolis antibacterial activity against EF ATCC 4082, isolated from pulpless teeth and compared it with calcium hydroxide [Ca(OH)2]. Methodology and results: The antimicrobial activity of HI propolis collected from Aasta Stingless Bee Honey Farm, Raub, Pahang, Malaysia, was tested against EF ATCC 4082 using disc diffusion, agar-well diffusion, broth microdilution methods, and scanning electron microscope (SEM) analysis. Calcium hydroxide [Ca(OH)2] and 5% dimethyl sulfoxide (DMSO) were positive and negative controls, respectively. Findings show that the agar-well diffusion method outperforms the disc diffusion method, with a statistically significant larger inhibition zone (Propolis: 10 +/- 0.000 mm, Ca(OH)2: 13.3 +/- 0.577 mm). Propolis (MIC: 6.25 mg/mL and MBC: 6.25 mg/mL) and Ca(OH)2 (MIC: 1.56 mg/mL and MBC: 1.56 mg/mL) effectively eliminated EF ATCC 4082 and their differences are not statistically significant. SEM analysis revealed the propolis at MBC value effectively lysed the EF ATCC 4082 cell wall compared to the Ca(OH)(2). Conclusion, significance and impact of study: The agar-well diffusion method is a more appropriate method in oralpropolis study. Propolis displayed promising antimicrobial properties, especially against EF and may be a good option for use as an intracanal medication in endodontics. Further tests requiring a longer period to investigate the prolonged antimicrobial effects, antibiofilm and anti-adherence properties, and effects against other EF strains and oral pathogens are suggested.