Application of an Ultrasonic Nebulizer Closet in the Disinfection of Textiles and Footwear

Abstract

The emergence of the coronavirus disease 2019 (COVID-19) pandemic highlighted the importance of disinfection processes in health safety. Textiles and footwear have been identified as vectors for spreading infections. Therefore, their disinfection can be crucial to controlling pathogens' dissemination. The present work aimed to evaluate the effectiveness of a commercial disinfectant aerosolized by an ultrasonic nebulizer closet as an effective method for disinfecting textiles and footwear. The disinfection was evaluated in three steps: suspension tests; nebulization in a 0.08 m³ closet; nebulization in the upscaled 0.58 m³ closet. The disinfection process of textiles and footwear was followed by the use of bacteriophages, bacterial spores, and bacterial cells. The disinfection in the 0.58 m³ closet was efficient for textiles (4 log reduction) when bacteriophage Lambda, Pseudomonas aeruginosa, and Bacillus subtilis were used. The footwear disinfection was achieved (4 log reduction) in the 0.08 m³ closet for Escherichia coli and Staphylococcus aureus. Disinfection in an ultrasonic nebulization closet has advantages such as being quick, not wetting, being efficient on porous surfaces, and is performed at room temperature. Ultrasonic nebulization disinfection in a closet proves to be useful in clothing and footwear stores to prevent pathogen transmission by the items' widespread handling.

Keywords: Gram-negative bacteria; Gram-positive bacteria; aerosol; bacterial spores; bacteriophage; disinfection; footwear; pathogen transmission control; textiles; ultrasonic nebulization closet.

Figure 1

Log₁₀ reduction achieved in disinfection of Bacillus atrophaeus DSM 2277 spores by suspension test with different disinfectant concentrations. VIRCOV BAC 360 disinfectant was tested at the following dilutions: 100% disinfectant; 1/2 (v/v) dilution; 1/4 (v/v) dilution; 1/8 (v/v) dilution; 1/16 (v/v) dilution. The contact time was 2 min. The error bars in the graph represent the standard deviation of the mean of three replicates (n = 3). Statistical difference between groups was evaluated by one-way analysis of variance (ANOVA) with post hoc comparisons made by the Tukey test. ns: not significant with p-value > 0.05; ****: significant with p-value < 0.0001.

Figure 2

Log₁₀ reduction achieved in disinfection of fabric by nebulization in a 0.08 m³ closet. VIRCOV BAC 360 disinfectant was tested at 1/2 (v/v) and 1/3 (v/v) dilutions. The indicators tested were B. atrophaeus DSM 2277 spores and bacteriophage Escherichia virus Lambda DSM 4499. The disinfection time consisted of 2 min of disinfectant nebulization plus 5 min of rest without nebulization. The error bars in the graph represent the standard deviation of the mean of two replicates (n = 2) for B. atrophaeus DSM 2277 spores tests and three replicates (n = 3) for bacteriophage Lambda DSM 4499 tests. Statistical difference between groups was evaluated by two-way ANOVA with post hoc comparisons made by the Tukey test. ***: significant with p-value < 0.001; ****: significant with p-value < 0.0001.

Figure 3

Log₁₀ reduction achieved in disinfection of a folded cotton towel of 460 × 720 mm by nebulization in a 0.08 m³ closet. VIRCOV BAC 360 disinfectant was used at 1/3 (v/v) dilution. The indicators tested were B. atrophaeus DSM 2277 spores, bacteriophage Lambda DSM 4499, Escherichia coli DSM 30083, and Staphylococcus aureus DSM 20231. The disinfection time consisted of 2 min of disinfectant nebulization plus 5 min of rest without nebulization. The error bars in the graph represent the standard deviation of the mean of three replicates (n = 3).

Figure 4

Log₁₀ reduction achieved in disinfection of a footwear item by nebulization in a 0.08 m³ closet. VIRCOV BAC 360 disinfectant was used at 1/3 (v/v) dilution. The indicators tested were B. atrophaeus DSM 2277 spores, bacteriophage Lambda DSM 4499, E. coli DSM 30083, and S. aureus DSM 20231. The disinfection time consisted of 2 min of disinfectant nebulization plus 5 min of rest without nebulization. The error bars in the graph represent the standard deviation of the mean of three replicates (n = 3).

Figure 5

Log₁₀ reduction achieved in disinfection of fabric by nebulization in the upscaled 0.58 m³ closet. VIRCOV BAC 360 disinfectant was used at a 1/3 (v/v) dilution. The indicators tested were B. atrophaeus DSM 2277 spores, bacteriophage Lambda DSM 4499, E. coli DSM 30083, Pseudomonas aeruginosa DSM 1117, S. aureus DSM 20231, and Bacillus subtilis DSM 10. For the disinfection time, a short disinfection cycle and a long disinfection cycle were tested. The short disinfection cycle consisted of 2 min of nebulization, 2 min of rest without nebulization, and 2 min of aerosol extraction from the closet interior. For its part, the long disinfection cycle consisted of 4 min of nebulization, 4 min of rest without nebulization, and 2 min of aerosol extraction from the closet interior. The error bars in the graph represent the standard deviation of the mean of three replicates (n = 3). Statistical difference between groups was evaluated by two-way ANOVA with post hoc comparisons made by the Tukey test. ns: not significant with p-value > 0.05; *: significant with p-value < 0.05; ***: significant with p-value < 0.001.