Pretreatments for Microbial Analysis and Evaluation of Hygiene of Wet Towels and Wet Wipes

Abstract

The demand for hygiene products has increased worldwide since the outbreak of global COVID-19. As the hygiene products market is expanding, it is necessary to manage microbial contamination in wet towels and wet wipes. This study evaluated pretreatment methods for microbial recovery from wet towels and wipes and microbial contamination levels in wet towels and wipes with the pretreatment method. Escherichia coli (NCCP14038 and NCCP14039), Staphylococcus aureus (ATCC25923 and ATCC29213), and Pseudomonas aeruginosa (NCCP10250 and NCCP11229) were inoculated on five fabric materials of wet towels and wet wipes. The recovery rates of the bacteria from wet towels and wet wipes using three pretreatment methods (pummeling, hand shaking, and portion cutting method) were investigated. Using the selected pretreatment method, the contamination levels of E. coli, S. aureus, and P. aeruginosa were evaluated for 238 wet towels and 244 wet wipes, which were collected in April to August, 2019. The presence of toxA and antibiotic resistance of P. aeruginosa isolated from wet towels were evaluated. The overall recovery rates of the pummeling method and hand shaking method were higher than the portion cutting method. Considering the convenience, the pummeling method was used to investigate the microbial contamination in the wet towels and wet wipes. P. aeruginosa was detected in two wet towels at an average of 9.9x102 CFU/towel. E. coli and S. aureus were not detected in both wet towels and wipes. P. aeruginosa isolates showed no resistances to piperacillin, piperacillin-tazobactam, aztreonam, and gentamicin, but had toxA. The results indicate that the pummeling method is the most appropriate pretreatment method for the recovery of microorganisms, and microbial analysis showed that this method could be useful in monitoring microbial contamination in wet towels and wet wipes.