Comparison of cleaning fabrics for bacterial removal from food-contact surfaces

Survival of foodborne pathogens on stainless steel soiled with different food residues

Insufficient and ineffective cleaning practices can cause food residues to remain in kitchen and can facilitate bacterial attachment and persistence by protective films. The present study investigated the survival of five major foodborne pathogens on stainless steel coupons, in the presence of cooked rice, whole eggs, and soymilk. Foodborne pathogens showed different survival rates by desiccation and disinfection depending on food residues. Overall, the pathogens showed stronger survival than the control at 0.13-3.97 log CFU/coupon with 5% residues, and at 0.75-5.29 log CFU/coupon with 50% residues. Staphylococcus aureus was not affected by the food residue with showing the least difference in concentration, while Escherichia coli O157:H7 showed the most significant increase by food residue. The cells with cooked rice were observed using FE-SEM, and demonstrated bacterial binding or embedment. All results suggest that food safety can be practically ensured by food residue types and appropriate cleaning and disinfectants.

In Situ Visualization of Particle Motions during Wipe Sampling of Explosives and Other Trace Particulate Materials

Surface texture tailoring has the potential to increase the effectiveness of dry particle collection wipes, as a wipe's topographical features control the intimate surface contact made with particles on the substrate (critical for van der Waals-governed adhesion). However, texture-tailoring approaches have not yet been widely explored, in part because of a lack of understanding of the specific wipe topographies and wipe/particle interactions that maximize particle collection. Here we describe an in situ optical microscopy technique that enables direct observation of micrometer-scale particle-wipe interactions occurring at the wipe-substrate interface during contact sampling. The technique is demonstrated for nonwoven meta-aramid (Nomex) collection wipes with particles ranging from 1 to 90 μm in diameter and substrates of different topographies (glass and nylon coil zipper). Experiments with hemispherically coated Janus particles allow rolling motions to be distinguished from sliding motions, providing detailed information about how particles move prior to capture or release by the wipe. Particle-fiber and particle-particle interactions are seen to play important roles in particle capture, suggesting that conventional sphere-on-plane models are inadequate to describe adhesion behavior in these systems. Micrographs show how loose, flexible fibers in roughened textile wipes interrogate the valleys of uneven substrate topographies, allowing capture of particles that might otherwise be trapped within the substrate's grooves and depressions. The materials used in this work are specifically relevant to explosives detection, but the in situ visualization technique is transferable for the study of any application involving dry particle collection, such as toxic substance sampling and dust removal.

Impact of test protocols and material binding on the efficacy of antimicrobial wipes

BACKGROUND

The use of effective cleaning/disinfectant products is important to control pathogens on healthcare surfaces. With the increasing number of wipe products available, there is a concern that combination of a formulation with the wrong material will decrease the efficacy of the product. This study aimed to use a range of efficacy test protocols to determine the efficacy of four formulations before and after binding to three commonly used wiping materials.

METHODS

Two quaternary ammonium (QAC)-based products, one hydrogen-peroxide-based product and one neutral cleaner were combined with microfibre, cotton or non-woven materials and tested for efficacy against Pseudomonas aeruginosa and Staphylococcus aureus with two surface tests (ASTM E2197-17 and EN13697-15) and two 'product' tests (ASTM E2967-15 and EN16615-15).

FINDINGS

Overall, the impact of using different materials on formulation efficacy was limited, except for an alkyl(C_12-16)dimethylbenzylammonium chloride-based product used at 0.5% v/v. The hydrogen peroxide product was the most efficacious regardless of the material used. The results from wipe test ASTM E2967-15 were consistent with those from the surface tests, but not with EN16615-15 which was far less stringent.

CONCLUSIONS

The use of different wiping cloth materials may not impact severely on the efficacy of potent disinfectants, despite the absorption of different volumes of formulation by the materials. QAC-based formulations may be at higher risk when a low concentration is used. There were large differences in efficacy depending on the standard test performed, highlighting the need for more stringency in choosing the test to make a product claim on label.

Bacterial adhesion capacity on food service contact surfaces

The aim of this study was to analyse the adhesion of E. coli, P. aeruginosa and S. aureus on food contact materials, such as polyethylene terephthalate, silicone, aluminium, Teflon and glass. Surface roughness, streaming potential and contact angle were measured. Bacterial properties by contact angle and specific charge density were characterised. The bacterial adhesion analysis using staining method and scanning electron microscopy showed the lowest adhesion on smooth aluminium and hydrophobic Teflon for most of the bacteria. However, our study indicates that hydrophobic bacteria with high specific charge density attach to those surfaces more intensively. In food services, safety could be increased by selecting material with low adhesion to prevent cross contamination.

Wipes coated with a singlet-oxygen-producing photosensitizer are effective against human influenza virus but not against norovirus

Transmission of enteric and respiratory viruses, including human norovirus (hNoV) and human influenza virus, may involve surfaces. In food preparation and health care settings, surfaces are cleaned with wipes; however, wiping may not efficiently reduce contamination or may even spread viruses, increasing a potential public health risk. The virucidal properties of wipes with a singlet-oxygen-generating immobilized photosensitizer (IPS) coating were compared to those of similar but uncoated wipes (non-IPS) and of commonly used viscose wipes. Wipes were spiked with hNoV GI.4 and GII.4, murine norovirus 1 (MNV-1), human adenovirus type 5 (hAdV-5), and influenza virus H1N1 to study viral persistence. We also determined residual and transferred virus proportions on steel carriers after successively wiping a contaminated and an uncontaminated steel carrier. On IPS wipes only, influenza viruses were promptly inactivated with a 5-log10 reduction. D values of infectious MNV-1 and hAdV-5 were 8.7 and 7.0 h on IPS wipes, 11.6 and 9.3 h on non-IPS wipes, and 10.2 and 8.2 h on viscose wipes, respectively. Independently of the type of wipe, dry cleaning removed, or drastically reduced, initial spot contamination of hNoV on surfaces. All wipes transferred hNoV to an uncontaminated carrier; however, the risk of continued transmission by reuse of wipes after 6 and 24 h was limited for all viruses. We conclude that cleaning wet spots with dry wipes efficiently reduced spot contamination on surfaces but that cross-contamination with noroviruses by wiping may result in an increased public health risk at high initial virus loads. For influenza virus, IPS wipes present an efficient one-step procedure for cleaning and disinfecting contaminated surfaces.