title: Inhibition of bacterial growth by different mixtures of propofol and thiopentone.
abstract: Propofol is, as a result of its formulation, an ideal bacterial and yeast culture medium. An outbreak of sepsis in humans and an increase in wound infections in dogs has been ascribed to the use of propofol. It has been previously reported that a 1:1 mixture of propofol and thiopentone has bactericidal properties. This study was undertaken to determine if further serial mixtures of propofol and thiopentone maintained the bactericidal properties. Mixtures of 1:1 (solution A), 5:1 (solution B), 10:1 (solution C), 50:1 (solution D) and 100:1 (solution E) of 1% propofol to 2.5 % thiopentone, 2.5% thiopentone (solution T), 1% propofol (solution P) and saline (solution S) were prepared and inoculated with between 10(5) and 10(6) colony-forming units of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. A sample was withdrawn from each solution at 0, 1, 6, 12, 48 and 120 hours after inoculation and a bacterial count was performed. This study showed that thiopentone and solution A behaved in similar fashion by inhibiting bacterial growth and was bactericidal after 48 hours. Solution B was not bactericidal against S. aureus and C. albicans. Propofol and solutions D and E all supported growth of all the organisms tested. These data indicate that mixtures of propofol and thiopentone at a ratio less than 1:1 do not maintain the bactericidal properties.
authors.affiliation: Section of Anaesthesiology, Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa. kenneth@fourwaysvet.co.za
authors.forename: K E
authors.initials: KE
authors.lastname: Joubert
authors.forename: J
authors.initials: J
authors.lastname: Picard
authors.forename: M
authors.initials: M
authors.lastname: Sethusa
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects / Q000254:growth & development; D015169:Colony Count, Microbial; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004357:Drug Synergism; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D015742:Propofol / Q000737:chemistry* / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D013874:Thiopental / Q000737:chemistry* / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D013874:Thiopental; D015742:Propofol