Effectiveness and Durability of a Quaternary Ammonium Compounds-Based Surface Coating to Reduce Surface Contamination

Abstract

Foodborne diseases are of major concern as they have a significant impact on public health, both socially and economically. The occurrence of cross-contamination of food in household kitchens is a serious threat and the adoption of safe food practices is of paramount importance. This work aimed to study the effectiveness and durability of a commercial quaternary ammonium compound-based surface coating which, according to the manufacturer, retains its antimicrobial activity for 30 days, and is suitable for all types of hard surfaces for the prevention and/or control of cross-contamination. For that, its antimicrobial efficacy, killing contact time and durability on three different surfaces-polyvinyl chloride, glass, and stainless-steel-against three pathogens-Escherichia coli ATCC 25922, Acinetobacter baumannii ESB260 and Listeria monocytogenes Scott A-were tested according to the current antimicrobial treated surfaces efficacy test (ISO22196:2011). The results showed that the antimicrobial coating was effective against all pathogens with a reduction of >5.0 log CFU/cm² in less than one minute for the three surfaces, but its durability was less than one week on all surfaces cleaned in the usual manner. Additionally, trace amounts (≤0.2 mg/kg) of the antimicrobial coating, which may migrate into food when contacting the surface, did not show cytotoxicity to human colorectal adenocarcinoma cells. The suggested antimicrobial coating has the potential to significantly reduce surface contamination, ensure surface disinfection and reduce the likelihood of cross-contamination in domestic kitchens, although it is less durable than suggested. The use of this technology in household settings is an attractive complement to the existing cleaning protocols and solutions that are already in place.

Keywords: antimicrobial activity; contact surfaces; foodborne pathogens; quaternary ammonium compounds.

Figure 1

Contact killing time for A. baumannii ESB260 (Ab); E. coli ATCC 25922 (Ec) and L. monocytogenes Scott A (Lm). Recovery of bacteria immediately after inoculation (T0) and after 24 h incubation (T24) on untreated surface. Recovery of bacteria immediately after inoculation (C1 min), after 10 min (C10 min), 20 min (C20) and 24 h incubation (C24 h) on each treated surface. The results are means based on data from three replicates, and standard deviations are indicated by error bars. Equivalent lowercase letters mean no significant differences between each condition (p > 0.05). The dotted line indicates the detection limit of the enumeration technique.

Figure 2

Recovery of bacteria immediately after inoculation (T0) and after 24 h incubation (T24) on untreated surfaces; and after 24 h incubation (C24 h; C24B’; C24C’; C24DG’ and C24D’) on each treated surface on day 1 for A. baumannii ESB260 (Ab1), E. coli ATCC 25922 (Ec1) and L. monocytogenes Scott A (Lm1). Antimicrobial activity of the coating on day 7 for A. baumannii ESB260 (Ab2), E. coli ATCC 25922 (Ec2) and L. monocytogenes Scott A (Lm2) with the recovery of bacteria immediately after inoculation (T0) and after 24 h incubation (T24) on untreated surface; and after 24 h incubation on treated surface cleaned with bleach (C24B); damp cloth (C24C); commercial degreaser (C24DG) and commercial disinfectant (C24D). The results are means based on data from three replicates, and standard deviations are indicated by error bars. Equivalent lowercase letters mean no significant differences between each condition (p > 0.05). The dotted line indicates the detection limit of the enumeration technique.

Figure 3

Metabolic activity of Caco-2 cells exposed to trace concentrations of the antimicrobial coating. The results are means based on data from two replicates, and standard deviations are indicated by error bars. Different letters indicate values significantly different (ANOVA test followed by Tukey HSD post-hoc, p < 0.05).