Measuring residual activity of topical antimicrobials: is the residual activity of chlorhexidine an artefact of laboratory methods?

Residual activity of chlorhexidine gluconate (CHG) was evaluated by pretreating hands with CHG and then touching Staphylococcus aureus dried on to stainless steel discs. By this method, no reduction in bacteria was observed up to 15 min, suggesting that residual CHG does not offer protection against contamination with transient micro-organisms in clinical practice.