Growth of Staphylococcus aureus in Four Intravenous Anesthetics

Patient infections related to the use of propofol have been reported. To investigate the growth of Staphylococcus aureus in propofol, thiopental, methohexital, etomidate, and 0.9% saline containing no bacteriostatic drug, these preparations were inoculated and samples were plated onto blood agar at 0,3,6,21,24, and 27 h. The number of colony-forming units (CFU) on the plates was then determined after 24 h of incubation. Samples from the inoculated etomidate solution showed zero CEU at 3 h and thereafter, whereas 21 h were required by the methohexital and thiopental solutions to reduce the number of CFU to zero. For normal saline, no significant change in CFU was seen before the first 6 h, then the number of CFU gradually declined, although some S. aureus CFU were still present at 27 h. Inoculation of the propofol emulsion resulted in a substantial growth of S. aureus between 6 and 21 h after inoculation. We conclude that, of the preparations tested, only propofol was an excellent medium for the rapid growth of S. aureus. Meticulous sterile technique, therefore, is advised when handling it.