Resistances to benzalkonium chloride of bacteria dried with food elements on stainless steel surface

Unlocking the Hidden Threat: Impacts of Surface Defects on the Efficacy of Sanitizers Against Listeria monocytogenes Biofilms on Food-contact Surfaces in Tree Fruit Packing Facilities

Food-contact surfaces showing signs of wear pose a substantial risk of Listeria monocytogenes contamination and may serve as persistent sources of cross-contamination in fresh produce packinghouses. This study offers a comprehensive exploration into the influence of surface defects on the efficacies of commonly used sanitizers against L. monocytogenes biofilms on major food-contact surfaces. The 7-day-old L. monocytogenes biofilms were cultivated on food-contact surfaces, including stainless steel, polyvinyl chloride, polyester, low-density polyethylene, and rubber, with and without defects and organic matter. Biofilms on those surfaces were subjected to treatments of 200 ppm chlorine, 400 ppm quaternary ammonium compound (QAC), or 160 ppm peroxyacetic acid (PAA). Results showed that surface defects significantly (P < 0.05) increased the population of L. monocytogenes in biofilms on non-stainless steel surfaces and compromised the efficacies of sanitizers against L. monocytogenes biofilms across various surface types. A 5-min treatment of 200 ppm chlorine caused 1.84-3.39 log10 CFU/coupon reductions of L. monocytogenes on worn surfaces, compared to 2.79-3.93 log10 CFU/coupon reduction observed on new surfaces. Similarly, a 5-min treatment with 400 ppm QAC caused 2.05-2.88 log10 CFU/coupon reductions on worn surfaces, compared to 2.51-3.66 log10 CFU/coupon reductions on new surfaces. Interestingly, PAA sanitization (160 ppm, 1 min) exhibited less susceptibility to surface defects, leading to 3.41-4.35 log10 CFU/coupon reductions on worn surfaces, in contrast to 3.68-4.64 log10 CFU/coupon reductions on new surfaces. Furthermore, apple juice soiling diminished the efficacy of sanitizers against L. monocytogenes biofilms on worn surfaces (P < 0.05). These findings underscore the critical importance of diligent equipment maintenance and thorough cleaning processes to effectively eliminate L. monocytogenes contamination on food-contact surfaces.

New Trends in Photodynamic Inactivation (PDI) Combating Biofilms in the Food Industry-A Review

Biofilms cause problems in the food industry due to their persistence and incompetent hygiene processing technologies. Interest in photodynamic inactivation (PDI) for combating biofilms has increased in recent years. This technique can induce microbial cell death, reduce cell attachment, ruin biofilm biomolecules and eradicate structured biofilms without inducing microbial resistance. This review addresses microbial challenges posed by biofilms in food environments and highlights the advantages of PDI in preventing and eradicating microbial biofilm communities. Current findings of the antibiofilm efficiencies of this technique are summarized. Additionally, emphasis is given to its potential mechanisms and factors capable of influencing biofilm communities, as well as promising hurdle strategies.

Influence of New Compound Disinfectant From N-Dodecyl-2-(Piridin-1-Ium)Acetamide Chloride on Pathogenic Microorganisms in Poultry Houses

With the development of large-scale and intensive poultry farming, environmental disinfection has become particularly important, and the effectiveness of disinfection depends upon the performance of the disinfectants. Quaternate ammonium salt is a group of positively charged polyatomic ions with both antibacterial and antiviral activities. In order to prepare an ideal disinfectant for poultry farms, we combined a quaternate ammonium salt N-dodecyl-2-(piridin-1-ium)acetamide chloride with two other disinfectants (chlorhexidine acetate and glutaraldehyde), respectively. The antimicrobial activity, mutagenicity, and safety of the compound disinfectants were assessed by the European Standard methods using ATCC strains and clinical isolates. The results showed that both compound disinfectants meet the requirements of microbial reduction, and their effectiveness was not affected by organic matter. Quaternary ammonium disinfectant resistance genes were not detected in the strains tested indicating that bacteria are less likely to develop resistance to these compound disinfectants. Ames test showed that there was no detectable mutagenicity in the strains treated with the compound disinfectants. In vivo experiment showed that both compound disinfectants did not have significant pathological effect in mice. The bactericidal effect of the compound disinfectants was not significantly different among strains of different sources (p>0.05). Clinical tests showed that compound disinfectant had a good bactericidal effect on the air and ground of poultry farms. These results show that quaternary ammonium salts in combination with other compounds can enhance the bactericidal effect and can be used safely in poultry feedlots. This study provides a technical reference for the development of a new quaternate ammonium compound disinfectant with strong disinfection effect and low irritation.

Development of a Benzalkonium Chloride Based Antibacterial Paper for Health and Food Applications

Pathogenic bacteria and other microorganisms pose a potent threat to humans by causing various infectious diseases. To control the spread of infection, different antibacterial products have been developed. However, most of them are known to be associated with health hazards, environmental pollution, complex fabrication, and/or higher cost. To address these issues, in this study, a low cost, biodegradable and human skin compatible antibacterial paper has been developed. A quaternary ammonium compound, benzalkonium chloride (BKC) has been used for paper surface treatment. The concentration of aqueous solution of BKC coated on paper was varied from 0.1 wt% to 0.2 wt%. No external binder was required for coating BKC onto paper. The efficacy of the coated paper was investigated against Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 8739 bacterial strains. This antibacterial paper is highly effective against both strains with the concentrations of BKC being within the allowable limit for cytotoxic effects. The optimum concentration of BKC coated on paper can be considered as 0.15 wt%, as nearly 100% inhibition was achieved with it against both strains. The developed antibacterial paper is suitable for being used in the industry for disinfection and food packaging purposes, and also by the public for hand sanitization.

Efficacy of Commercial Sanitizers Used in Food Processing Facilities for Inactivation of Listeria Monocytogenes, E. Coli O157:H7, and Salmonella Biofilms

Bacteria entrapped in biofilms are a source of recurring problems in food processing environments. We recently developed a robust, 7-day biofilm microplate protocol for creating biofilms with strongly adherent strains of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella serovars that could be used to examine the effectiveness of various commercial sanitizers. Listeria monocytogenes 99-38, E.coli O157:H7 F4546, and Salmonella Montevideo FSIS 051 were determined from prior studies to be good biofilm formers and could be recovered and enumerated from biofilms following treatment with trypsin. Extended biofilms were generated by cycles of growth and washing daily, for 7 days, to remove planktonic cells. We examined five different sanitizers (three used at two different concentrations) for efficacy against the three pathogenic biofilms. Quaternary ammonium chloride (QAC) and chlorine-based sanitizers were the least effective, showing partial inhibition of the various biofilms within 2 h (1-2 log reduction). The best performing sanitizer across all three pathogens was a combination of modified QAC, hydrogen peroxide, and diacetin which resulted in ~6-7 log reduction, reaching levels below our limit of detection (LOD) within 1-2.5 min. All treatments were performed in triplicate replication and analyzed by one way repeated measures analysis of variance (RM-ANOVA) to determine significant differences (p < 0.05) in the response to sanitizer treatment over time. Analysis of 7-day biofilms by scanning electron microscopy (SEM) suggests the involvement of extracellular polysaccharides with Salmonella and E. coli, which may make their biofilms more impervious to sanitizers than L. monocytogenes.

Comparative Evaluation of Different Sanitizers Against Listeria monocytogenes Biofilms on Major Food-Contact Surfaces

Contaminated food-contact surfaces are recognized as the primary reason for recent L. monocytogenes outbreaks in caramel apples and cantaloupes, highlighting the significance of cleaning and sanitizing food-contact surfaces to ensure microbial safety of fresh produce. This study evaluated efficacies of four commonly used chemical sanitizers at practical concentrations against L. monocytogenes biofilms on major food-contact surfaces including stainless steel, low-density polyethylene (LDPE), polyvinyl chloride (PVC), polyester (PET), and rubber. In general, efficacies against L. monocytogenes biofilms were enhanced by increasing concentrations of quaternary ammonium compound (QAC), chlorine, and chlorine dioxide, or extending treating time from 1 to 5 min. The 5-min treatments of 400 ppm QAC, 5.0 ppm chlorine dioxide, and 200 ppm chlorine reduced 3.0-3.7, 2.4-2.7, and 2.6-3.8 log₁₀ CFU/coupon L. monocytogenes biofilms depending on surfaces. Peroxyacetic acid (PAA) at 160 and 200 ppm showed similar antimicrobial efficacies against biofilms either at 1- or 5-min contact. The 5-min treatment of 200 ppm PAA caused 4.0-4.5 log₁₀ CFU/coupon reduction of L. monocytogenes biofilms on tested surfaces. Surface material had more impact on the efficacies of QAC and chlorine, less influence on those of PAA and chlorine dioxide, while organic matter soiling impaired sanitizer efficacies against L. monocytogenes biofilms independent of food-contact surfaces. Data from this study provide practical guidance for effective disinfection of food-contact surfaces in food processing/packing facilities.

Antimicrobial Coatings for Food Contact Surfaces: Legal Framework, Mechanical Properties, and Potential Applications

Food contact surfaces (FCS) in food processing facilities may become contaminated with a number of unwanted microorganisms, such as Listeria monocytogenes, Escherichia coli O157:H7, and Staphylococcus aureus. To reduce contamination and the spread of disease, these surfaces may be treated with sanitizers or have active antimicrobial components adhered to them. Although significant efforts have been devoted to the development of coatings that improve the antimicrobial effectiveness of FCS, other important coating considerations, such as hardness, adhesion to a substrate, and migration of the antimicrobial substance into the food matrix, have largely been disregarded to the detriment of their translation into practical application. To address this gap, this review examines the mechanical properties of antimicrobial coatings (AMC) applied to FCS and their interplay with their antimicrobial properties within the framework of relevant regulatory constraints that would apply if these were used in real-world applications. This review also explores the various assessment techniques for examining these properties, the effects of the deposition methods on coating properties, and the potential applications of such coatings for FCS. Overall, this review attempts to provide a holistic perspective. Evaluation of the current literature urges a compromise between antimicrobial effectiveness and mechanical stability in order to adhere to various regulatory frameworks as the next step toward improving the industrial feasibility of AMC for FCS applications.

Activity of essential oil-based microemulsions against Staphylococcus aureus biofilms developed on stainless steel surface in different culture media and growth conditions

Food safety is a fundamental concern for both consumers and the food industry, especially as the numbers of reported cases of food-associated infections continue to increase. Industrial surfaces can provide a suitable substrate for the development and persistence of bacterial organized in biofilms that represent a potential source of food contamination. The negative consumer perception of chemical disinfectants has shifted the attention to natural substances, such as plant extracts. The aim of this study was to investigate the possibility of using the essential oils (EOs) in the fight against S. aureus biofilms. First, the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Minimum Biofilm Inhibitory Concentration (MBIC), Minimum Biofilm Eradication Concentration (MBEC) of eleven EOs against S. aureus were determined. Cinnamomum cassia and Salvia officinalis EOs showed the greatest antibacterial properties with 1.25% MIC and MBC, 1.25% MBIC and 2.5% MBEC respectively. Gas Chromatography/Mass Spectrometry analysis revealed cinnamaldehyde (82.66%) and methoxy cinnamaldehyde (10.12%) as the most abundant substances of C. cassia, while cis-thujone (23.90%), camphor (19.22%) and 1.8-cineole (10.62%) of S. officinalis. Three different microemulsions, formulated with C. cassia, S. officinalis or both, were finally tested against S. aureus biofilms in different culture media and growth conditions, causing a >3 logarithmic reductions in S. aureus 24h-old biofilms and desiccated biofilms, and up to 68% of biofilm removal after 90min of exposure. The obtained data suggest the potential use of EOs, alone or in combination, for the formulation of sanitizers as alternative or in support in the disinfection of contaminated surfaces.

Benzalkonium runoff from roofs treated with biocide products - In situ pilot-scale study

Roof maintenance practices often involve the application of biocide products to fight against moss, lichens and algae. The main component of these products is benzalkonium chloride, a mixture of alkyl benzyl dimethyl ammonium chlorides with mainly C12 and C14 alkyl chain lengths, which is toxic for the aquatic environment. This paper describes, on the basis of an in-situ pilot scale study, the evolution of roof runoff contamination over a one year period following the biocide treatment of roof frames. Results show a major contamination of roof runoff immediately after treatment (from 5 to 30 mg/L), followed by an exponential decrease. 175-375 mm of cumulated rainfall is needed before the runoff concentrations become less than EC50 values for fish (280 μg/l). The residual concentration in the runoff water remains above 4 μg/L even after 640 mm of rainfall. The level of benzalkonium ions leaching depends on the roofing material, with lower concentrations and total mass leached from ceramic tiles than from concrete tiles, and on the state of the tile (new or worn out). Mass balance calculations indicate that a large part of the mass of benzalkonium compounds applied to the tiles is lost, probably due to biodegradation processes.

Chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of animal bacterial pathogens

Background:

To study chlorhexidine digluconate disinfectant effects on planktonic growth and biofilm formation in some bacterial field isolates from animals.

Objectives:

The current study investigated chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of veterinary bacterial pathogens.

Materials and Methods:

Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus. aureus and Streptococcusagalactiae (10 isolates for each) were examined for chlorhexidine digluconate effects on biofilm formation and planktonic growth using microtiter plates. In all of the examined strains in the presence of chlorhexidine digluconate, biofilm development and planktonic growth were affected at the same concentrations of the disinfectant.

Results:

Chlorhexidine digluconate inhibited the planktonic growth of different bacterial species at sub-MICs. But they were able to induce biofilm development of the E. coli, Salmonella spp., S. aureus and Str. agalactiae strains.

Conclusions:

Bacterial resistance against chlorhexidine is increasing. Sub-MIC doses of chlorhexidine digluconate can stimulate the formation of biofilm strains.

Efficacies of sodium hypochlorite and quaternary ammonium sanitizers for reduction of norovirus and selected bacteria during ware-washing operations

Cross-contamination of ready-to-eat (RTE) foods with pathogens on contaminated tableware and food preparation utensils is an important factor associated with foodborne illnesses. To prevent this, restaurants and food service establishments are required to achieve a minimum microbial reduction of 5 logs from these surfaces. This study evaluated the sanitization efficacies of ware-washing protocols (manual and mechanical) used in restaurants to clean tableware items. Ceramic plates, drinking glasses and stainless steel forks were used as the food contact surfaces. These were contaminated with cream cheese and reduced-fat milk inoculated with murine norovirus (MNV-1), Escherichia coli K-12 and Listeria innocua. The sanitizing solutions tested were sodium hypochlorite (chlorine), quaternary ammonium (QAC) and tap water (control). During the study, the survivability and response to the experimental conditions of the bacterial species was compared with that of MNV-1. The results showed that current ware-washing protocols used to remove bacteria from tableware items were not sufficient to achieve a 5 log reduction in MNV-1 titer. After washing, a maximum of 3 log reduction in the virus were obtained. It was concluded that MNV-1 appeared to be more resistant to both the washing process and the sanitizers when compared with E. coli K-12 and L. innocua.

Chemical sanitizers to control biofilms formed by two Pseudomonas species on stainless steel surface

The biofilm formation of Pseudomonas aeruginosa and Pseudomonas fluorescens on AISI 304 stainless steel in the presence of reconstituted skim milk under different temperatures was conducted, and the potential of three chemical sanitizers in removing the mono-species biofilms formed was compared. Pseudomonas aeruginosa cultivated in skim milk at 28 °C presented better growth rate (10.4 log CFU.mL-1) when compared with 3.7 and 4.2 log CFU.mL-1 for P. aeruginosa and P. fluorescens cultivated at 7 °C, respectively. Pseudomonas aeruginosa formed biofilm when cultivated at 28 °C. However, only the adhesion of P. aeruginosa and P. fluorescens was observed when incubated at 7 °C. The sodium dichloroisocyanurate was the most efficient sanitizer in the reduction of the adhered P. aeruginosa cells at 7 and 28 °C and those on the biofilm, respectively. The hydrogen peroxide was more effective in the reduction of adhered cells of P. fluorescens at 7 °C.