Cross-contamination in dishwashers.

Dishwashers are used in central hospital kitchens and ward kitchens to provide clean crockery. Soil recipes based on international standards were tested in order to evaluate the performance of a general dishwasher. In normal use of dishwashers, adherent soils are left on the crockery before cleaning. Different adherent soils, both with and without bacterial contamination, were used to show the effectiveness of the dishwasher to remove this type of soil. It was shown that contamination will occur from the dishwater to crockery with adherent soil. These results demonstrate the importance of cleaning soiled surfaces of crockery mechanically in the dishwashing process. Otherwise cross-contamination, and thereby the spread of infections, may occur.