Purpose: To evaluate the effectiveness of detergent and sanitizers and combinations of both in their ability to remove attached STECS from stainless steel (SS) and polyurethane coupons.
Methods: Using a STEC cocktail (one strain from each serogroup), cells were allowed to attach and grow on SS and polyurethane coupons for 24 h at 25°C. Coupons were rinsed to remove loosely attached cells and treated with detergent (detergent/water), sanitizer (water/sanitizer), bleach (water/bleach), detergent/sanitizer, detergent/bleach, control (water only), or no treatment. Coupons were immersed into the solutions for 5 min for each step and a concentration of 200 ppm for sanitizer and bleach. STEC cells were removed from the coupons, serial dilutions were made in BPW and plated onto Tryptic Soy Agar, incubated at 37°C for 24 h, and counted. Counts were converted to log CFU/cm2 before statistical analysis.
Results: A significant (P < 0.0001) treatment effect occurred, with quaternary ammonium, bleach, and combinations of both with detergents being the most effective treatments. All treatments significantly reduced STECs when compared to the untreated coupons (14 log CFU/cm2). Log reductions ranged from a 5 log CFU/cm2 difference observed on coupons treated with detergent, to a 12 log CFU/cm2 reduction with bleach only.
Significance: These results show that a complete cleaning and sanitation program is important to processing plants and food service establishments to reduce the amount of STECs that could attach and grown on surfaces such as SS and polyurethane. Proper sanitary methods are important to processing plants, food establishments, and food markets.