Monitoring Substratum Hygiene Using an Everyday Complex Organic Soil: The Human Fingerprint

Human fingerprint residue is an example of a specific and complex organic-material/microorganism soil which is often present in a variety of environments that are required to be hygienic. When applied onto surfaces a fingerprint may affect cleanability and influence bacterial retention, alter topography and in some cases, may even compromise the aesthetic qualities of the material. One of the most common modes of cross contamination in hygienic environments is via the human hand but this soil/microorganism matrix is rarely studied in controlled conditions. Modifications were made to published sweat and sebum standard formulations to allow a gram positive organism (Staphylococcus aureus) and a gram negative representative (Escherichia coli) to survive in a synthetic fingerprint soil for subsequent hygienic assessment of a range of surfaces. Alongside this, a method has been developed for depositing a range of organic soils in specific quantities and arrangements (e.g., the synthetic fingerprint soil in a fingerprint pattern) onto a range of substrata to allow surfaces to be more accurately assessed for cleanability.