Gadolinium-based MR contrast media: potential for growth of microbial contaminants when single vials are used for multiple patients.

OBJECTIVE

To assess potential risk if single-dose vials of gadolinium-based contrast media are used for multiple patients. The use of multidose vials can pose a significant risk if contaminants are accidentally introduced into the vials and proliferate. Therefore, we tested the ability of gadolinium-based contrast to support the growth of a variety of microbial pathogens.

MATERIALS AND METHODS

We collected the unused portions of 15 single-use vials of gadolinium-based contrast media. The residual contrast material was refrigerated after use and checked for sterility prior to inoculation with a selection of gram-positive and gram-negative bacteria and yeast. Contrast material was incubated at room temperature and at 4 degrees C, and quantitative cultures were performed at 0, 24, 48, and 72 hr and at 7 days.

RESULTS

No microbial growth occurred from cultures of the used contrast solutions prior to inoculation. None of the organisms tested in our study proliferated in the contrast material. All test organisms persisted at least 48 hr after inoculation at both temperatures. At 7 days, Staphylococcus aureus, Streptococcus epidermidis, and Corynebacterium jeikeium were recovered in significant quantities. Colony counts of Serratia odorifera rapidly decreased at room temperature but persisted beyond 7 days at 4 degrees C.

CONCLUSION

The risk of contaminating vials of contrast agents punctured aseptically is small. Our study demonstrates a lack of proliferation of organisms in the two gadolinium-based compounds tested, suggesting that these solutions could be used for more than one procedure.