The effect of an antibacterial washing-up liquid in reducing dishwater aerobic plate counts.

Aims: To assess any significant differences in the aerobic plate count (APC) of catering dishwaters following the use of a traditional, nonantibacterial or an antibacterial washing-up liquid.

Methods And Results: A dishwashing trial was undertaken within a commercial restaurant of 6 weeks duration (3 weeks with each washing-up liquid in a randomized, weekly pattern). Five replicate samples were taken from the dishwater at the end of the washing-up operation, on three separate occasions each day corresponding to mid-morning, lunchtime and mid-afternoon meal preparations.

Conclusions: The antibacterial product was shown to significantly reduce the APC by an average log10 reduction of 1.81 CFU ml(-1) (98.5%) as compared with the traditional product. APC were lower for each of the three weekly time periods for the antibacterial product. Continued use of the antibacterial product did not decrease the APC of the dishwater, though with the traditional product, dishwater counts increased throughout the trial week.

Significance And Impact Of The Study: Antibacterial washing-up liquids, with proven activity in controlling levels of microorganisms in dishwaters, could play a significant role in reducing the risk of cross-contamination between washed articles during washing-up operations.