Image analysis method for evaluation of specific and non-specific hand contamination

Area of Science:

• Microbiology
• Food Safety
• Public Health

Background:

• Assessing hand contamination is crucial for preventing foodborne illnesses.
• Current methods for evaluating hand hygiene can be time-consuming and complex.

Purpose of the Study:

• To evaluate a novel image analysis technique for quantifying hand contamination.
• To determine the efficacy of hand washing procedures using this method.

Main Methods:

• Experimental contamination of hands with pure bacterial cultures (Escherichia coli, Listeria innocua, Pseudomonas flourescens) and raw food.
• Palm imprints on agar plates followed by incubation.
• Digital image analysis of bacterial colonies on agar plates.

Main Results:

• The image analysis method successfully monitored bacterial levels from 1 to 10(6) CFU cm(-2) palm for pure cultures.
• A linear correlation was established between image analysis data and bacterial counts (10(3) to 10(6) CFU cm(-2) palm) for raw chicken contamination.
• Sensitivity and specificity were influenced by the type of agar and contamination source.

Conclusions:

• Image analysis of palm imprints is a viable method for assessing food-related hand contamination.
• The technique is simple, partly automatable, and has a short sampling time, making it suitable for large field trials on hand hygiene.