A laboratory model for the investigation of contact transfer of micro-organisms

The model was based on grasping a fabric-covered bottle contaminated with a strain of Staphylococcus saprophyticus, then grasping a sterile fabric-covered bottle and counting the organisms transferred. When the donor fabric was moist 10% of the available cells passed onto the hands, but this fell to 0.05% when the inoculum dried. Transfer from wet hands to the fabric amounted to 85%, but in the complete model only 0.06% of the available cells were transferred. The model was used to assess simple methods of degerming the hands. Washing the hands reduced transfer by 95%, while washing in 70% alcohol reduced transfer by 99.99%. Lesser procedures investigated included applying 0.2 ml of 80% ethanol to the hands, which reduced transfer by 93%.