If blood-contaminated devices or inadequately washed devices are immersed in a disinfectant, the proteins contaminating them may become denatured or adhere tight to the devices due to the action of the disinfectant. It is therefore essential to completely remove contaminants from the devices prior to the use of a disinfectant. In clinical practice, however, it is often the case that devices, etc., immersed in various disinfectants, are sent to the materials supply unit and are washed there. Bearing this practice in mind, we conducted the present study, designed to examine the effects of disinfectants in causing denaturation of blood and to show how the proteins exposed to disinfectants would hamper the washing procedure, using a washing effect evaluation indicator coated with blood components. When combinations of blood (1 ml) and each of 8 disinfectants (4 ml) were tested, 6 combinations caused denaturation of proteins (leading to deposition), and the remaining 2 combinations caused proteins to assume a gel form. When the washing effect evaluation indicator was washed in an enzymatic cleaner or an alkaline cleaner after it was immersed in a disinfectant, the protein which had become denatured due to the disinfectant was removed only slightly. When a washer disinfector was used, the protein which had become denatured due to Glutaraldehyde was not removed completely, The protein which had become denatured due to prior treatment with Glutaraldehyde, Peracetic acid, Orthophthalaldehyde or Benzal-konium chloride was not removed completely by ultrasonic washing. We have thus demonstrated that treatment with a disinfectant caused denaturation of protein, and that the denatured protein resists washing with cleaners. The results of this study indicate that treatment with a disinfectant prior to washing (i.e., pre-cleaning disinfection) should not be performed.
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