The resistance of Bacillus atrophaeus spores to the bactericidal activity of peracetic acid is influenced by both the nature of the solid substrates and the mode of contamination

Abstract

Aims: To evaluate the impact of the mode of contamination in relation with the nature of solid substrates on the resistance of spores of Bacillus atrophaeus ‐selected as surrogates of Bacillus anthracis‐ to a disinfectant, peracetic acid. Methods and Results: Six materials confronted in urban and military environments were selected for their different structural and physicochemical properties. In parallel, two modes of contamination were examined, i.e. deposition and immersion. Deposition was used to simulate contamination by an aerosol and immersion by an extended contact with liquids. A pronounced difference in the biocontamination levels and spatial organization of spores was observed depending on the mode of contamination and the nature of the solid substrate considered, with consequences on decontamination. Contamination by immersion led to lower efficiency of peracetic acid decontamination than contamination by deposition. Infiltration of spores into porous materials after immersion is one reason. In contrast, the deposition mode aggregates cells at the surface of materials, explaining the similar disinfecting behaviour of porous and nonporous substrates when considering this inoculation route. Conclusions: The inoculation route was shown to be as influential a parameter as material characteristics (porosity and wettability) for decontamination efficacy. Significance and Impact of the Study: These results provide comparative information for the decontamination of B. atrophaeus spores in function of the mode of contamination and the nature of solid substrates.

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

“…The microscopic method can be used to test disinfection results obtained using standard assessments on liquid-sampled cells. For example, we previously showed by such a standard assessment that the nature of the solid substrate has an influence on disinfection efficiency (13). We arrived at the same conclusion by applying the microscopic method on both glass and painted stainless steel (data not shown).…”

“…Three independent stock of spores of B. atrophaeus CIP 7718 (Institut Pasteur, France) were prepared as previously described (13). Briefly, after growth on a sporulation medium, the spores were collected by scraping the surface of the agar and then washed four times in 0.15 mol of NaCl liter…”

“…Studies have been performed to optimize sampling efficiency as a function of the type of material and the mode of contamination (6,11,19,22), and Sagripanti and Bonifacino (22) developed a threestep method that, according to the authors, allowed to obtained near 100% of sampling efficiency for some materials. However, most of the time, total recovery is hard to be achieved and typical sampling efficiencies range from 20 to 90% for bacterial spores (11,13,19). Efficiencies inferior to 10% have sometimes been obtained for porous substrates (21).…”

Is peracetic acid suitable for the cleaning step of reprocessing flexible endoscopes?

“…Depending on its concentration and pH value [98] , it is effective against bacteria including H. pylori, fungi, mycobacteria, viruses including hepatitis B virus, and bacterial spores [35,66,68,[99][100][101][102][103][104][105][106][107][108][109][110][111][112] , though for specific isolates, such as Mycobacterium gordonae, the exposure time may have to be prolonged to 20 min to achieve the required efficacy [67] . However, despite its broad spectrum of antimicrobial activity it is not suitable for sterilizing surgical instruments [113] .…”

Additional Effects of Silver Nanoparticles on Bactericidal Efficiency Depend on Calcination Temperature and Dip-Coating Speed

“…Three of the most common methods of water or surface sterilization are chlorination, ozonation, and ultraviolet irradiation (3, 21). However, the reaction of chlorine with natural organic matter in water forms disinfection by-products, such as haloacetic acids and trihalomethanes (e.g., chloroform), that may be harmful to human health.Bacillus atrophaeus was used as a biological indicator to monitor sterilization processes and development of biosafety methods (10,28,35). B. atrophaeus has two forms, vegetative cell and spore.…”