What is left to justify the use of chlorhexidine in hand hygiene?

The CDC guideline for hand hygiene describes chlorhexidine gluconate as an agent with "substantial residual activity". But not all studies support this claim. In both suspension tests (e.g. EN 13727) and tests under practical conditions (e.g. EN 1500) it is crucial to neutralize any residual activity in the sampling fluid in order to make sure that the agent does not continue to damage surviving cells after exposure. The neutralization step must also be validated. If this is not done the efficacy may be significantly overestimated, and the healthcare professional may rely on data which do not represent the true efficacy of an agent. A review of eight studies which are cited to support "substantial residual activity" show that none of them were performed with validated neutralization. Seven of them do not demonstrate any residual activity for chlorhexidine gluconate. Only in one study some residual activity is described but the validity of the study design does not allow make this claim as no neutralizing agents were used at all. The benefits of using an active agent must outweigh any risks in order to justify its use. If no real benefits are left for chlorhexidine gluconate in hand hygiene, all the risks count even more such as skin irritation, allergic reactions including anaphylactic shock, and acquired bacterial resistance. Unless there is new and valid evidence to clearly support a benefit of using chlorhexidine gluconate in hand hygiene, healthcare workers should prefer formulations without this agent.