To evaluate the efficacy of a multistep cleaning method using a cleaner and a chemical disinfectant on blood-contaminated angiographic catheters and spinal needles intended to be sterilized by hydrogen peroxide gas plasma.
A mixture of radiopaque iodine contrast, bovine blood (plus ethylenediaminetetraacetic acid), and a suspension of Bacillus subtilis spores was used to simulate catheterization and needle use. The mixture was a 1:1 proportion of contrast and blood, inoculated so that there was a final concentration of B subtilis spores of 1.0×106 colony-forming units (CFU)/mL. The inoculated devices were cleaned using a hydrogen peroxide solution at a concentration of 1.5±0.5 percent by weight, followed by distilled water with enzymatic detergent. After drying, the devices were sterilized with hydrogen peroxide gas plasma.
The initial B subtilis spore concentration inoculated into catheters and needles varied from 2.12×104 to 2.74×107 CFU/mL. The residual load of B subtilis spores after cleaning varied from zero (no count) to a maximum of 200 CFU/device. The multistep cleaning procedure was responsible for an average 5-log10 reduction of B subtilis spores in the catheter and needle lumens.
The hydrogen peroxide and enzymatic detergent aqueous solutions were shown to be efficacious when used as part of a multistep cleaning method. The low level of microbial contamination prior to sterilization with hydrogen peroxide gas plasma assured that the intended sterility assurance level was reached.
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