title: Growth of microorganisms in propofol and methohexital mixtures.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the growth of 4 different microorganisms in propofol, methohexital, and 1:1 and 1:3 mixtures of propofol and methohexital.
  
  
  METHODS
  The microbial growth of Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Escherichia coli in 1:1 and 3:1 mixtures of methohexital and 2 types of propofol was measured for 48 hours after mixing the solutions. Two of the 4 test solutions were composed of 1% methohexital combined with Diprivan (AstraZeneca Pharmaceuticals, Wilmington, DE), which uses EDTA as a microbial growth inhibitor. The growth of the same 4 microorganisms was also evaluated in 1:1 and 3:1 mixtures of 1% methohexital and a recently introduced generic propofol marketed by Baxter Pharmaceuticals (Deerfield, IL) that uses sodium metabisulfite as a preservative.
  
  
  RESULTS
  Combining either Diprivan or generic propofol with methohexital in a 1:1 or 1:3 mixture ratio resulted in a solution that, like methohexital alone, significantly resisted the growth of C albicans, E coli, S aureus, and P aeruginosa for 48 hours.
  
  
  CONCLUSIONS
  The results of our study suggest that 1:1 and 1:3 mixtures of propofol (either Diprivan or generic propofol) and methohexital behave similarly to methohexital alone by resisting growth of the microorganisms studied over the 48-hour time period. If, as has been reported elsewhere, the mixture of these 2 agents results in a solution with desirable anesthetic properties, its ability to resist microbial growth becomes clinically significant by extending the shelf-life of propofol in these mixtures.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Seton Hall University, St Joseph's Regional Medical Center, Paterson, NJ 07503, USA. harv04@yahoo.com
authors.forename: Bryan R
authors.initials: BR
authors.lastname: Harvey
authors.forename: Steven
authors.initials: S
authors.lastname: Ganzberg
mesh_terms: D000704:Analysis of Variance; D018686:Anesthetics, Intravenous / Q000737:chemistry*; D002176:Candida albicans / Q000254:growth & development*; D002614:Chelating Agents / Q000737:chemistry; D015169:Colony Count, Microbial; D004340:Drug Contamination; D016568:Drugs, Generic / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry; D004926:Escherichia coli / Q000254:growth & development*; D006801:Humans; D008723:Methohexital / Q000737:chemistry*; D011310:Preservatives, Pharmaceutical / Q000737:chemistry; D015742:Propofol / Q000737:chemistry*; D011550:Pseudomonas aeruginosa / Q000254:growth & development*; D013211:Staphylococcus aureus / Q000254:growth & development*; D013447:Sulfites / Q000737:chemistry; D013997:Time Factors
chemical_list: D018686:Anesthetics, Intravenous; D002614:Chelating Agents; D016568:Drugs, Generic; D011310:Preservatives, Pharmaceutical; D013447:Sulfites; C005200:sodium metabisulfite; D004492:Edetic Acid; D008723:Methohexital; D015742:Propofol