Antimicrobial activity of nanoemulsion on cariogenic Streptococcus mutans.
OBJECTIVE
To assess antimicrobial activities of nanoemulsion (NE) to control the adhesion and biofilm formation by Streptococcus mutans by in vitro.


METHODS
In vitro antimicrobial susceptibility of nanoemulsion was determined as per National Committee for Clinical Laboratory Standards guidelines and agar diffusion, serial dilution technique for the determination of minimum inhibitory concentration and minimum bactericidal concentration (MIC/MBC). Efficacy was tested by kinetics of killing, biofilm assay and scanning electron microscopy.


RESULTS
: NE concentrations ranging from 1:100 to 1:10,000 dilutions were effective against S. mutans as shown through MIC/MBC assays. NE showed antimicrobial activity against planktonic cells at high dilutions, confirmed by time kill studies. 4-day-old S. mutans biofilms were treated with NE; subsequent reductions of bacterial cell counts were noticed with decreasing dilutions. Staining of NE-treated biofilms with LIVE/DEAD BacLight resulted in dead cell areas of up to 48% in 1 min, 84% at 1h and significant (<0.05) increases in dead cell counts at all time points. Damage to cell membranes and cell walls of S. mutans by NE was demonstrated using scanning electron microscopy (SEM).


CONCLUSIONS
These results suggest that nanoemulsion has effective antibacterial activity against S. mutans and may be a useful medication in the prevention of dental caries.
Department of Comprehensive Dentistry, MC 7919, USA. ramalingamk@uthscsa.edu
Ramalingam
R
Karthikeyan
Bennett T
BT
Amaechi
H Ralph
HR
Rawls
Valerie A
VA
Lee
D000704:Analysis of Variance; D058491:Bacterial Load; D018441:Biofilms / Q000187:drug effects*; D002594:Cetylpyridinium / Q000494:pharmacology; D003731:Dental Caries / Q000382:microbiology*; D004655:Emulsions / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures; D017830:Octoxynol / Q000494:pharmacology; D013024:Soybean Oil / Q000494:pharmacology; D013194:Staining and Labeling; D013295:Streptococcus mutans / Q000187:drug effects*
D004655:Emulsions; D013024:Soybean Oil; D017830:Octoxynol; D002594:Cetylpyridinium