Comparing the antibacterial efficacy and functionality of different commercial alcohol-based sanitizers

by Kaiyang Lim, Wei Yi Li, Afrah Dinata, En Ting Ho

The use of alcohol-based sanitizers has been recommended as an effective alternative to clean hands, especially in the case when hand washing is not doable. This is especially critical with the COVID-19 pandemic, where personal hygiene is an important factor to deter the spread of the virus. This study assesses and evaluates the differences in antibacterial efficacy and functionalities of five different commercial alcohol-based sanitizers with different formulations. All sanitizers were able to provide instant sanitization functionality, effectively killing 5x10⁵ CFU/mL of inoculated bacteria. However, comparing pure alcohol-based sanitizers against alcohol-based sanitizers with a secondary active ingredient demonstrated that the addition of a secondary active ingredient enhanced the effectiveness and functionalities of the sanitizers. Alcohol-based sanitizers with secondary active ingredients demonstrated a more rapid antimicrobial mode of action, eradicating all 10⁶ CFU/mL of bacteria within 15 seconds of contact, in contrast to the 30 min for purely alcohol-based sanitizers. The secondary active ingredient also provided additional anti-biofilm functionality to prevent opportunistic microbes from attaching and proliferating on the treated surface, leading to serious biofilm formation. On top of that, treatment of surfaces with alcohol-based sanitizers with secondary active ingredients also imparted prolonged antimicrobial protection to the surface lasting up to 24 h. On the other hand, purely alcohol-based sanitizers do not seem to possess such quality with the treated surface being vulnerable to microbial contamination within minutes after application. These results highlighted the benefits of adding a secondary active ingredient in sanitizer formulation. However, care needs to be taken to evaluate the type and concentration of antimicrobial agents chosen as the secondary active ingredient.