Methodological approach of antibacterial surfaces characterization

The surface biocontamination is a very widespread phenomenon in the food industries, medical appliances...This biofouling can alter the products, leading to economic losses linked or not to health problems. Stainlesssteel is extensively used in the above mentioned markets because of its good cleanability, high corrosionresistance, stability, inertia under most circumstances.Nevertheless, in material research, an important way of investigation is the elaboration of material able to killmicroorganisms that are in contact with or limit their proliferation. The development of such surfaces requiresrobust and standardized methods to quantify the antimicrobial activity of those materials. Only few standardsare available such as JIS Z2801 which is based on a culture method. This standard was assessed andcompared to alternative methods. The study was carried out using stainless steel as the reference material,“antimicrobial” materials, and two bacterial species: E. coli and S. aureus.Because viability is not easily defined with a single physiological or morphological parameter, the obtainedresults show the possible overestimation of the material antimicrobial activity with cultivation methods suchas the JIS Z2801 standard. Thereby, to assess the antibacterial activity of materials, it is preferable to combinedifferent methodologies, such as culture and in situ detection

Prevention of biofilm on stainless steel: evaluation of anti-adhesive and antimicrobial properties of silver-nanocomposite thin films

International audienc

Contamination des surfaces et désinfection

International audienc

Possible Overestimation of Surface Disinfection Efficiency by Assessment Methods Based on Liquid Sampling Procedures as Demonstrated by In Situ Quantification of Spore Viability ▿

The standard test methods used to assess the efficiency of a disinfectant applied to surfaces are often based on counting the microbial survivors sampled in a liquid, but total cell removal from surfaces is seldom achieved. One might therefore wonder whether evaluations of microbial survivors in liquid-sampled cells are representative of the levels of survivors in whole populations. The present study was thus designed to determine the “damaged/undamaged” status induced by a peracetic acid disinfection for Bacillus atrophaeus spores deposited on glass coupons directly on this substrate and to compare it to the status of spores collected in liquid by a sampling procedure. The method utilized to assess the viability of both surface-associated and liquid-sampled spores included fluorescence labeling with a combination of Syto 61 and Chemchrome V6 dyes and quantifications by analyzing the images acquired by confocal laser scanning microscopy. The principal result of the study was that the viability of spores sampled in the liquid was found to be poorer than that of surface-associated spores. For example, after 2 min of peracetic acid disinfection, less than 17% ± 5% of viable cells were detected among liquid-sampled cells compared to 79% ± 5% or 47% ± 4%, respectively, when the viability was evaluated on the surface after or without the sampling procedure. Moreover, assessments of the survivors collected in the liquid phase, evaluated using the microscopic method and standard plate counts, were well correlated. Evaluations based on the determination of survivors among the liquid-sampled cells can thus overestimate the efficiency of surface disinfection procedures