Study on the method to quantify viable bacterial cellson the surface of endotracheal suction catheters

気管内吸引カテーテルに付着した一般細菌の生菌数測定方法について,超音波法およびチューブミキサーによ攪拌法を用いて検討した｡まず,人工的に緑膿菌を付着させた気管内吸引カテーテルを超音波処理することにより生菌数を測定した｡その結果,処理時間が1分を経過すると生菌数は減少をはじめ経時的に減少傾向を示した｡一方,攪拌法では0.5分の処理をピーク値としてその後の減少傾向は認められなかった｡次に,在宅療養患者に使用したカテーテルをチューブミキサーで0.5分攪拌後,生菌数の測定を行った｡また,同じカテーテルを用いて走査型電子顕微鏡による観察を行った結果,画面上の細菌数の印象と生菌数の測定結果に矛盾はなかった｡これらのことから気管内吸引カテーテルに付着した一般細菌の生菌数測定方法として,生理食塩水に入れたカテーテルをチューブミキサーで攪拌する方法が有用であると考えられた｡As a method for the detection of viable bacteria attached to endotracheal suction catheters, we evaluated sonication and dissociation using a tube mixer. The catheter fragments with Pseudomonas aeruginosa PAO1 were treated by each of the two methods, and viable cells in the elutions were counted. The highest number of viable cells was observed at 0.5 min by either method. The viable cell count decreased when the sonication time exceeded 1 min, while only a slight decrease of viable cells was observed by using a tube mixer. The catheters used for patients receiving care at home were fragmented and treated by a tube mixer to detach bacteria, and viable cells were counted. Electron microscopy observation showed an association between the viable cell count and morphology of surfaces of the catheters. These results suggest that adequate removal of bacteria attached to endotracheal suction catheters is possible by agitating catheter fragments for 0.5 min in physiological saline using a tube mixer