First-hand nicotine/tobacco exposure on Streptococcus Mutans biofilm and effects of sodium chloride, potassium chloride and potassium iodide salts

Abstract

Objective: The aim of this study is to investigate the effects of first hand nicotine exposure on Streptococcus mutans biofilm formation and the inhibitory effects of sodium chloride (NaCl), potassium chloride (KCl) and potassium iodide (KI) salts. This study examined bacterial growth with varying concentrations of NaCl, KCl and KI salts and nicotine levels consistent with primary levels of nicotine exposure. Design: A preliminary experiment was done to investigate the most likely effective concentration of NaCl, KCl and KI. Then, a 24-hour culture of S. mutans UA159 in microtiter plates was treated with nicotine (0-32 mg/ml) in Tryptic Soy broth supplemented with 1.0-percent sucrose (TSBS) simulating first hand exposure with and without 0.45 M of NaCl, 0.23 M of KCl and 0.113 M of KI. A spectrophotometer was used to determine total growth and planktonic growth. The biofilm was fixed, stained with crystal violet dye and the absorbance measured to determine biofilm formation. Results: The presence of 0.45 M of NaCl, 0.23 M of KCl and 0.113 M of KI significantly inhibited (p<0.05) first hand nicotine-induced S. mutans biofilm formation by 52 percent%, 79.7 percent, and 64.1 percent, respectively. Similar results were obtained for planktonic growth. Conclusion: These results provided more evidence regarding the negative effects of nicotine and also demonstrated the positive influence of these salts in reducing nicotine-induced biofilm formation, which needs be confirmed by in-vivo studies.