Time to relook at formulationsrecommended for hand sanitizers formulations -An in vitro study

Purpose: The world health organization (WHO) in 2009 in their consensus recommendation on hand hygiene has suggested two formulations of hand sanitizers which are also the basis of main components of most commercial and medical grade hand sanitizers today.We evaluated the in vitro antimicrobial efficacy of ten different hand sanitizers (seven commercial including herbal (sanitizer 1, 2, 3, 4, 5, 9, and 10) and three of medical grade (sanitizers 6, 7 and 8). Method: The efficacy of hand sanitizers was checked against five ATCC strains: Staphylococcus aureus, Staphylococcus hemolyticus, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecalis. Experiment was performed in three parts. The first part was performed in triplicate to see the zone of inhibition for each sanitizer. The second part was performed to see the duration of action of each hand sanitizer and third part (in triplicates) was performed to see the efficacy of active components individually (alcohol and disinfectant in different dilutions).Results: Sanitizers with ethanol and chlorhexidine as main ingredients (6 and 8) showed zone of inhibition for all tested gram positive and negative bacteria. Sanitizer 7 (propanol and mecetronium ethyl sulphate as main components) showed zone of inhibition for all tested bacteria except Pseudomonas aeruginosa. Other hand sanitizers did not show any zone of inhibition after incubation for 24 hours at 37oC. For second part hand sanitizer 6inhibited growth for all bacteria at all-time points (15, 30, 45 and60 seconds) and Sanitizer 8(ethanol and chlorhexidine as main components) showed growth inhibition only after 15seconds. Other hand sanitizers did not show any growth inhibition. For the third part, all dilutions of ethanol and propanol (60%, 70% and 80%) were unable to inhibit growth of any ATCC strain. Disinfectant 2.5v/v chlorhexidine was able to inhibit all five bacteria.0.2 gm mecetronium ethyl sulphate showed inhibition for all except Pseudomonas aeruginosa. Conclusion: Hand sanitizers with alcohol only as their main ingredient were unable to inhibit growth of ATCC strains. Hand sanitizers with both alcohol and disinfectant performed better .These findings preludes for further in vivo studies to validate 2009-WHO hand sanitizer preparations and suggest modifications.