前腕の清拭による綿タオルへのセレウス菌付着，時間経過と菌の増殖

Adhesion and Growth of Bacillus cereus on Cotton Towels after Forearm Wiping

要旨

　目的：清拭タオルに起因するとされる血流感染リスクを軽減するため，前腕の清拭による綿タオルへのセレウス菌付着と，保管による菌の増殖について検証した．

　方法：未使用の綿タオルで対象者50名の両前腕を清拭し，片側のタオルは清拭直後に，もう片側は24時間常温保管後にセレウス菌を検出した．

　結果：セレウス菌が検出されたタオルは清拭直後で7枚（14.0％），24時間保管後で37枚（74.0％）であり，セレウス菌数は，24時間保管後には約6,000倍に増加した．細菌検出の関連要因として，皮膚洗浄後の保湿剤等の塗布，前腕のムダ毛処理をしない場合にセレウス菌検出量が有意に多かった（p＜0.05）．

　結論：個人差はあるが，前腕にはセレウス菌が付着している．清拭後のタオルを常温保管し細菌が増殖することで，セレウス菌が芽胞を形成する可能性が高くなるため，使用したタオルの細菌増殖を抑制する必要がある．

　Purpose: The use of with Bacillus cereus (B.cereus)-contaminated towels for bed baths can cause bloodstream infections in immunocompromised patients. This study aimed to assess the extent of B. cereus adhesion and growth on towels wiped on forearms.

　Methods: We recruited 50 healthy subjects aged 20-68 years between August and October 2021. Both forearms of each participant were wiped with clean warm towels. The number of B. cereus colonies were immediately determined after wiping for the right-arm towels and after storing the towels at room temperature (24-26℃) for 24 hours, for the left-arm towels. The relationship between the number of B. cereus colonies and attributes was analyzed.

　Results: Seven (14.0％) and 37 towels (74.0％) were found to contain B. cereus immediately after wiping and following 24-hour storage, respectively. On average, the B. cereus count was 6,000 times higher after 24-hour storage than immediately after wiping. Individuals who applied moisturizer had a higher number of B. cereus colonies on towels immediately after wiping compared to those who did not (p＜0.05). In towels stored for 24 hours after wiping, individuals who had not undergone arm hair removal had a higher number of B. cereus colonies compared to those who had (p＜0.05).

　Conclusion: Despite individual differences, B. cereus can adhere to human forearms. Storage of towels at room temperature after wiping leads to bacterial growth and increased possibility of B. cereus spore formation; therefore, suppression of bacterial growth on used towels is necessary.