Transfer of bacteria from fabrics to hands and other fabrics: development and application of a quantitative method using Staphylococcus aureus as a model

Aims: To develop and apply a quantitative protocol for assessing the transf er of bacteria fi om bleached and undyed fabrics of 100% cotton and 50% cot ton + 50% polyester (poly cotton) to fingerpads or other pieces of fabric. Methods and Results: Test pieces of the fabrics were mounted on custom-made stainless steel carriers to give a surface area of 1 cm in diameter, and e ach piece seeded with about 10(5) cfu of Staphylococcus aureus from an over night broth culture; the inoculum contained job fetal bovine serum as the s oil load. Transfer from fabric to fabric nus performed by direct contact us ing moist and dry fabrics. Transfers from fabrics to fingerpads of adult vo lunteers were tested using moist, dry and re-moistened pieces of the fabric s, with or without friction during the contact. Bacterial transfer from fab rics to moistened fingerpads nas also studied, All the transfers were condu cted under ambient conditions at an applied pressure of 0.2 kg cm(-2) After the transfer, the recipient fingerpads or fabric pieces were eluted, the e luates spread-plated, along with appropriate controls, on tryptic so agar a nd the percentage transfer calculated after the incubation of the plates fo r 24 h at 37 degreesC. Conclusions: Bacterial transfer from moist donor fabrics using recipients w ith moisture was always higher than that to and from dry ones. Friction inc reased the level of transfer from fabrics to fingerpads by as much as fivef old. Bacterial transfer from poly cotton was consistently. higher when comp ared with that from all-cotton material. Significance and Impact of the Study: The data generated should help in the development of better models to assess the role fabrics may. pla! as vehic les for infectious agents. Also, the basic design of the reported methodolo gy lends itself to work with other types of human pathogens.