Optimal method for culturing vascular prosthetic grafts.

Vascular prosthetic infection may be underrecognized when identified by standard culture techniques. Improved microbiologic methodology may enhance detection of bacteria in prosthetic graft specimens, and thus may alter clinical decisions. Quantitative culture techniques were employed to compare three methods of enhancing bacterial recovery from Dacron graft cylinders seeded with commonly encountered bacterial pathogens. Methods included: (1) ultrasonic bath treatment, (2) direct ultrasonic disruption, and (3) agitation on a Vortex mixer. Ultrasonic bath treatment released bacteria with colony counts that were consistently greater by 1 log than direct ultrasonic disruption and Vortex agitation. Direct ultrasonic disruption at high energy levels selectively killed gram-negative bacteria by as much as a 4 log decrease in viable organisms. Agitation (Vortex mixing) of the specimen produced the lowest counts among the three methods tested. These data would indicate that a 5-min ultrasonic bath treatment was the optimal method of preparation of vascular prostheses for bacterial culture.