In vitro evaluation of the antimicrobial activity of a castor oil-based irrigant

The antimicrobial activity of irrigating solutions-Endoquil (castor oil det ergent), 2% chlorhexidine gluconate solution, and 0.5% NaOCl solution-was e valuated against Gram-positive cocci (Micrococcus luteus, Staphylococcus au reus, Enterococcus faecalis, Staphylococcus epidermidis, Streptococcus muta ns, and Streptococcus sobrinus), Gramnegative rods (Escherichia coli and Ps eudomonas aeruginosa), and the yeast Candida albicans. Activity was evaluat ed using the two-layer agar diffusion technique. The base layer was obtaine d by pouring 10.0 ml of Muller Hinton Medium or 10.0 ml of Brain Heart Infu sion agar in a Petri dish. After solidification a 5.0 ml seed layer of Mull er Hinton Medium or Brain Heart Infusion agar with inoculum (10(6)/ml) was added. Absorbent paper disks (6.0 mm in diameter) immersed in the solutions were placed at equidistant points. Plates were maintained at room temperat ure for 2 h for prediffusion of the solutions and incubated at 37 degreesC for 24 h. The candle jar system was used for the Brain Heart Infusion agar plates. All tests were performed in duplicate. After incubation the medium was optimized with 0.05 g% triphenyltetrazolium chlorate gel and inhibition halos were measured. All bacterial strains were inhibited by 2.0% chlorhex idine gluconate. Endoquil was effective against Grampositive microorganisms , and 0.5% NaOCl was effective only against S. aureus.