Enhancement of bactericidal effect of Chlorhexidine using choline augmentation as a natural additive

•Multiple recent studies confirm the detrimental effects of long-term usage of Chlorhexidine on health and the environment.•The capacity of Choline in reducing the amount of Chlorhexidine required for antibacterial activity was investigated.•The interaction of Chlorhexidine and Choline was revealed as synergistic activity.•The activity of Chlorhexidine in the presence of interfering substances was preserved up to 20% more when it was combined with choline.•Choline can be suggested for augmentation of Chlorhexidine formulations leading to reduction in the excess environmental release of this antiseptic agent. The long-term use of Chlorhexidine (CHG) at high concentrations has detrimental effects on health and the environment. This research was aimed to evaluate the antibacterial capacity of CHG in the presence of choline as a natural additive to reduce the amount CHG required for the activity. The newly obtained formulation was evaluated for its stability and efficiency under physicochemical stresses. The checkerboard test was also performed to evaluate the type of CHG-additive interaction in a combinational state. The MIC of CHG was reduced up to five-fold in combination with choline at the concentration of 50mg/L and five log cfu/mL at 3 minutes of exposure. Chlorhexidine activity in combination with choline was preserved 20% more in the presence of interfering substances. The activity between CHG and choline was demonstrated as synergistic with FICI of 0.375. At sub MIC concentrations of both CHG (≤20 mg/L) and choline (≤6 mg/L) the observed interaction was synergy. While the significant interaction at high concentrations for both compounds was indifferent manner. The lysis effect of the CHG 20 mg/L was diminished in the presence of choline. Our suggested CHG formulation demonstrated rapid antimicrobial efficacy which can be a useful adjunct to infection control strategies currently employed in healthcare facilities. In conclusion, CHG can be combined with natural compounds as additives for enhanced synergistic antimicrobial activity.