Efficacy of Double Manual Cleaning Versus Automated Cleaning for Removal of Biofilm of Hinged Surgical Instruments
Authors: Costa Dayane , Castillo Roel , Lopes Lillian Kelly , Tipple Anaclara , Hu Honghua , Vickery Karen 
Published: November 2020

Objectives: To evaluate the efficacy of double manual cleaning (DMC) with enzymatic followed by alkaline detergent for removing biofilm on hinged surgical instruments compared to automated cleaning by the washer-disinfector. Methods: Biofilm of Staphylococcus aureus (ATCC 25923) was formed in vitro on hemostatic forceps (Fig. 1). Biofilm-covered forceps were rinsed in distilled water and subjected to one of the following cleaning regimes (n = 5 forceps each): Group 1 forceps were soaked in sterile water for 5 minutes. Group 2-DMC forceps were soaked in enzymatic detergent, brushed 5 times on each face, rinsed with filtrated water (0.2 µm), soaked in alkaline detergent, brushed 5 times each face, rinsed with filtrated water (0.2 µm), and dried with sterile cloth. For group 3-DMC plus hinge inner brushing (n = 5), the forceps were soaked in detergents and brushed as in group 2, including hinge inner brushing (2-mm lumen brush) (Fig. 1). In group 4 (automated cleaning in a washer/disinfector), forceps were prewashed, washed once, washed again, rinsed, thermally rinsed, and dried. After the treatments, forceps were evaluated for microbial load (counting of colony-forming units), residual protein (BCA protein assay kit), and biofilm (scanning electron microscopy). Results: There was no statistically significant differences between the microbial load and protein level contaminating the forceps subjected to DMC (group 2) and the positive control group. The DMC with hinge inner brushing group (group 3) and the automated cleaning group (group 4) demonstrated a significantly reduced microbial load: reduction averages of 2.8 log 10 (P = .038) and 7.6 log10 (P ≤ .001), respectively. The protein level remaining on the forceps also significantly decreased: 2.563 μg (P = .016) and 1,453 μg (P = .001), respectively, compared to the positive control group. There was no statistically significant difference between DMC with hinge inner brushing and automated cleaning (groups 3 and 4) for all of the tests performed. None of the cleaning methods completely removed biofilm and/or soil from the forceps hinge internal region (Fig. 1). Conclusions: Automated cleaning had the best efficacy for removing biofilm. However, DMC with hinge inner brushing was an acceptable alternative cleaning method for sterilizing service units with only manual cleaning available, as is the case in most low- and middle-income countries. Neither automated nor any manual cleaning regimes were able to completely remove biofilm and soil from the forceps hinged area, and the amount of protein left after automated and DMC plus hinge brushing was higher than the recommended. Cleaning is the most important step for the reprocessing of reusable medical devices; thus, efforts must be undertaken to improve cleaning in different social and economic realities and scenarios.Funding: This study was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – CAPES.Disclosures: None