[Sterilization of phacoemulsification and vitrectomy instruments. Contamination and evaluation].
BACKGROUND
Contamination of automated surgical equipment is widely disregarded as a potential source of perioperative infection. We investigated the possibility of contamination of the aspiration fluid by the vacuum control manifold (VCM). The normal, unsterile internal VCM was compared with a modified external VCM that was regularly disinfected.


METHODS
We investigated 37 aspiration fluid specimens from routine cataract and vitrectomy operations performed with automated evacuation systems. There were 25 specimens from three automated evacuation systems equipped with an internal VCM (experimental groups) and 12 specimens from one system equipped with a modified external VCM (control group). No hygiene procedures were used with the hidden internal VCM, but the modified external VCM was regularly rinsed and filled with 70% isopropanol overnight. Specimens were collected under sterile conditions, centrifuged, cultured for bacterial growth on blood agar and MacConkey agar for 24-48 h at 37 degrees C, and analyzed microbiologically.


RESULTS
Aspiration fluids of irrigation/aspiration systems used for intraocular surgery were found to be severely contaminated with bacteria originating from the VCM. In all aspiration fluid specimens from internal VCM systems, 2(+)-4+ bacterial growth was found. Stenotrophomonas maltophilia (17), Comamonas acidovorans (8), and Agrobacterium radiobacter (13) were found most frequently. All 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 experimental and control groups (P = 0.0001, chi 2).


CONCLUSIONS
We found that the aspiration fluid of common phaco- and vitrectomy systems was strongly contaminated by bacteria originating from the internal VCM. The technical modification of an external VCM allows easy disinfection and prevents contamination of the aspiration fluid.
Minõ de Kaspar
H
H
Augenklinik der Ludwig-Maximilians-Universität München.
Grasbon
T
T
Kampik
A
A
D001431:Bacteriological Techniques; D015169:Colony Count, Microbial; D004866:Equipment Contamination; D006801:Humans; D018918:Phacoemulsification / Q000295:instrumentation*; D011446:Prospective Studies; D013242:Sterilization; D014821:Vitrectomy / Q000295:instrumentation*