Automated surgical equipment requires routine disinfection of vacuum control manifold to prevent postoperative endophthalmitis

Purpose: Contamination of automated surgical equipment is a potential source of postoperative endophthalmitis. The effect of disinfecting the unsterile vacuum control manifold (VCM) on contamination of the aspiration fluid was studied. Design: Comparative prospective microbiologic contamination study. Specimens and Controls: The 37 aspiration fluid specimens studied or examined consisted of 25 from three automated evacuation systems equipped with an internal VCM (experimental groups) and 12 from one system equipped with a modified external VCM (control group). in addition, the tubings of two internal VCMs were investigated. Methods: We investigated aspiration fluid specimens from routine cataract and vitrectomy operations performed with automated evacuation systems. After tracing the source of contamination to the internal VCM, the system was modified, creating an external VCM with the possibility for disinfection, and the study was continued. Whereas no sterilizing rinsing procedures were applied to the hidden internal VCM, the modified external VCM was regularly rinsed and filled overnight with 70% isopropanol. All samples were collected under sterile conditions, centrifuged, and cultured for bacterial growth on blood agar and MacConkey agar for 24 to 48 hours at 37 degrees C. The samples of the two internal VCMs were cultured for fungi as well. Main Outcome Measures: Bacterial growth was quantified, and bacteria and fungi were isolated and identified according to standard microbiologic procedures, Results: In all aspiration fluid specimens from internal VCM-systems, 2+ to 4+ bacterial growth was found. Pseudomonas-related genera (Stenotrophomonas maltophilia, 17x; Comamonas acidovorans, 8x; Chryseomonas spp., 3x), Agrobacterium radiobacter (13x), Flavobacterium spp. (3x), and Micrococcus luteus (7x) were found most frequently. The tubing of the two VCMs contained biofilms exhibiting several of these bacteria and fungi. Ail specimens from the modified external VCM-system remained sterile, There was a significant difference with regard to the frequency of contamination of the aspiration fluid between the experimental and control groups (chi-square: P = 0.0001). Conclusions: The technical modification described herein allows facile hygienic measures, by which contamination of aspiration fluid by the VCM can be eliminated, which otherwise can be a significant source of contamination. (C) 2000 by the American Academy of Ophthalmology.