RESUMEN
Aim: The present study evaluated the antimicrobial efficacy of Chlorhexidine, Nisin and Linezolid and a control group (Normal saline ) against Enterococcus faecalis (EF). Methods: Human single rooted premolars with type I canal anatomy were instrumented with ProTaper using NaOCl as an irrigant. Supension of EF was inoculated into each root specimen and incubated. The medicaments were syringed into each root and incubated. After 24 hours, 8 samples per group (among the 4 groups) were retrieved. A hole was drilled on each root, and the dentinal shavings obtained were allowed to fall in brain-heart infusion (BHI) broth. Dilutions from the broth were plated and spread over blood agar. Colony-forming units (CFU) of EF was counted. The procedure was repeated after 72 hrs and 1 week. Results: In group Nisin, the mean CFU was 10.6250 at 24 hrs, 6.6250 at 72 hrs and 6.2500 after 1 week respectively (statistically significant). In group Chlorhexidine, mean CFU was found to be the lowest of 10.5000 at 24 hrs, with further gradual increase to 13.7500 at 72 hrs and further increase to 15.8750 by 1 week. Similarly, in group linezolid , the mean CFU was found to decrease from 49.0000 at 24 hrs to 29.8750 at 72hrs and then increase to 34.8750 in 1 week.