Antimicrobial assay of combination surfactant irrigant regimen on vancomycin‑resistant Enterococcus faecalis. An in vitro direct contact test

Manikandan Ravinanthanan, Mithra N. Hegde, Veena A. Shetty, Suchetha Kumari


Background: Vancomycin‑resistant enterococci (VRE) are on the rise globally in primary
intraradicular infections and resistant to most intracanal irrigants and medicaments. The aim of this
study was to evaluate the efficacy of irrigants and identify a cost‑effective regimen to eradicate VRE.
Materials and Methods: In this in vitro study irrigants were categorized as primary and surfactant
groups with individual concentrations consisting of 10 samples each. Primary irrigants; sodium
hypochlorite (NaOCl), chlorhexidine (CHX), and iodine potassium iodide (IKI) were prepared
in concentrations of 5%, 2.5%, 2%, and 1%. Surfactants cetrimide (CTR) and sodium dodecyl
sulfate (SDS) were prepared in concentrations of 0.25%, 0.5%, 1%, and 2%. Biopure MTAD was
chosen as the control group. ATCC 51299 (VRE) was evaluated for antimicrobial susceptibility to
the above irrigants by direct contact test for 5 min. The effect of each test irrigant was determined
by calculating the percentage kill of viable bacteria by spectrophotometer. Statistical analysis was
done by means of a one‑way ANOVA and Mann–Whitney U‑test (P < 0.05 consider significant).
Results: About 2.5% and 5% CHX were significant over mixture of tetracycline, acid and detergent
(MTAD) (P < 0.05). 5% CHX could achieve 100% elimination while 2.5% CHX and 5% IKI had
99.90%. 2% CHX and 2.5% IKI had 99% effective kill percentage. All concentrations of NaOCl
were ineffective (90%) as compared to MTAD (95%). CTR (0.5%, 1% and 2%) and SDS (2%) were
significant (P < 0.05) over MTAD. Combination surfactant regimens of 2% CHX +0.5% CTR and 2%
CHX +1% SDS achieved 99.90% eradication potential and were significant (P < 0.05) over MTAD.
Conclusion: Surfactant regimens were highly effective and superior to MTAD. CTR and SDS by
their organic solvent property enhanced the antibacterial action of CHX.
Key Words: Enterococci, root canal irrigants, vancomycin

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