Comparison of antimicrobial activity of Mupirocin and Chlorhexidine against Enterococcus faecalis using agar diffusion test

Background: E. faecalis is a commonly recovered microbe in failing root canals. Due to limitations of currently popular endodontic irrigants, there is need to find novel antibacterial agents against E. Faecalis. Mupirocin is a broad spectrum antibiotic agent which is effective against gram positive organisms including MRSA. Purpose: The purpose of this study was to compare the antibacterial activity of Mupirocin with contemporary root canal irrigants (2% Chlorhexidine and 5% NaoCl) against Enterococcus faecalis. Materials and Methods: 6 serial dilutions of Mupirocin (1%, 0.5%, 0.25%, 0.125%, 0.0625%, 0.0312%) in sterile distilled water were obtained from 2% w/w Mupirocin ointment. The anti-bacterial efficacy of these Mupirocin dilutions, 2% chlorhexidine and 5% NaOCl was tested against E. faecalis ATCC 29212 strain using agar diffusion method. The zone of inhibition around the wells was measured in mm using a Vernier calliper. Results: The zone of inhibition of 0.0312% mupirocin (6th serial dilution) was comparable to 2% Chlorhexidine and hence this concentration of mupirocin was selected for comparision. The mean values for the zones of inhibition were 19.61, 21.83 and 8.67 mm respectively for 2% chlorhexidine, 0.0312% mupirocin and 5% NaOCl and the differences were statistically significant. (p<0.05) Conclusion: Based on our results, 0.0312% mupirocin may be preferable over 2% chlorhexidine as a final irrigant in the preparation of root canals.