Bacterial contamination of contrast media stored after opening

A barium suspension, iohexol, iopamidol and ioxaglate which were diluted with tapwater and 0.9% NaCl and dextrose saline (4% and 0.18%) were made into aliquots of 10 ml and stored at 4 degrees C, room temperature and 37 degrees C for 8 weeks. Regular handling and bacterial cultures were performed. These studies confirmed that environmental organisms do contaminate these solutions and that they also support viable organisms, but do not become significantly colonized at room temperature or 4 degrees C. The solutions should be stored at room temperature or at 4 degrees C. The diluted barium solution was the contrast medium least contaminated and if it is not contra-indicated for other reasons should be used in preference to low osmolality water soluble contrast media on the basis of its cost, radiological contrast and low microbial contamination rate.