Evaluation of Vitrectomy Machines as a Source of False-Positive Culture Contamination in Endophthalmitis

Abstract

We sought to determine whether a venturi-aspiration vitrectomy machine could contaminate a vitrectomy culture. Ninety vitrectomies were simulated in a hospital operating room and were cultured with standard techniques. An additional 90 control specimens were cultured in the exact same manner, but the vitrectomy machine was not used. Instead, the control specimens were placed directly into a sterile vitrectomy cassette. Contamination rates in the two groups were compared. Contamination occurred in four of 90 vitrectomy-simulation cultures and in three of 90 control cultures. This difference in contamination rate was not statistically significant. Although the result of a culture of the vitrectomy effluent can be false-positive, the source of contamination is not likely to be the vitrectomy machine.