THE MICROBIOLOGIC EFFECT OF GAS FILTRATION

Background: Air and expansile gases commonly are injected into the eye in both vitreoretinal surgery and anterior segment surgery. Although the halogenated gases are filtered routinely before injection, air oft en is not prepared in this manner. This study was designed to investig ate the effect of filtration on the microbiology of gas mixtures. Meth ods: Two separate studies were conducted, one examining medical grade perfluoropropane gas (C3F8), and the other evaluating air collected fr om an ophthalmic operating room or emergency room. Aliquots of air or gas were collected through a 0.22-mu m filter before and after filtrat ion. The filter discs were cultured for bacterial and fungal organisms . Results: Of 514 samples collected, none grew either bacterial or fun gal organisms. There was no difference with regard to recovered microb es between filtered and unfiltered air or C3F8, nor was there a differ ence between operating room air and emergency room air. Positive contr ols using aerosolized microorganisms yielded heavy growth. Conclusion: Based on results obtained in this study and available information on the concentration of airborne microbes, the microbiologic effect of ga s filtration is of little significance for volumes routinely injected in ophthalmic surgery.