New sequential-touch method to determine bacterial contact transfer rate from finger to surface

Area of Science:

• Microbiology
• Infectious Disease Transmission
• Surface Science

Background:

• Infections can spread through surface contact.
• Accurate quantification of bacterial transfer from skin to surfaces is crucial for understanding transmission dynamics.

Purpose of the Study:

• To develop and validate a novel method for precisely evaluating the bacterial transfer rate from a human finger to a surface.
• To assess the efficacy of this new method using a model bacterium and resident microflora.

Main Methods:

• Utilized Staphylococcus aureus as a model organism to inoculate a thumb.
• Performed sequential touches between the contaminated thumb and clean microscope slides.
• Quantified bacteria on slides using in situ culture and colony-forming units (CFUs), fitting data to an exponential decay model.

Main Results:

• The average bacterial transfer rate for S. aureus was determined to be 12.9% under baseline conditions.
• CFU counts on glass surfaces demonstrated a good fit with the exponential decay function.
• Validation using resident microflora showed no significant difference in transfer rate compared to the standard strain.

Conclusions:

• The developed method accurately quantifies microbial transfer rates from fingers to surfaces.
• The new technique offers a low-workload approach for reliable bacterial transfer evaluation.
• Findings contribute to a better understanding of pathogen transmission via touch surfaces.