Storage of specimens at 4 degrees C or addition of sodium fluoride (1%) prevents formation of ethanol in urine inoculated with Candida albicans.
The microbial synthesis of ethanol was investigated in urine specimens containing 0.5% or 1.0% (w/v) glucose and inoculated with the yeast Candida albicans (100 cfu/mL). Aliquots (10 mL) of urine were dispensed into plastic tubes containing enough sodium fluoride to give final concentrations of 0.1%, 0.25%, 0.5%, 0.75%, 1%, and 2% (w/v), and C. albicans was added. The tubes were tightly stoppered and allowed to stand either at room temperature (22 degrees C) or in a refrigerator (4 degrees C) for up to 34 days before concentrations of ethanol were determined by headspace gas chromatography. Urine samples stored at 22 degrees C without sodium fluoride produced 0.25 g/L ethanol after two days, and the concentration increased to 2.10 g/L and 4.50 g/L after eight days for specimens containing 0.5% (w/v) and 1% (w/v) glucose, respectively. The ratio of the serotonin metabolites 5-hydroxytryptophol/5-hydroxyindoleacetic acid (5HTOL/5HIAA) in urine remained within the reference range (< 15 pmol/nmol) despite high concentrations of ethanol being produced. Urine samples kept at 4 degrees C did not produce any ethanol (< 0.01 g/L) even without sodium fluoride present as a preservative. The production of ethanol by C. albicans was stopped completely by adding 1% or 2% (w/v) sodium fluoride but not by concentrations of 0.75% (w/v) or less. The microbial synthesis of ethanol in urine samples initially stored at room temperature without sodium fluoride was slowed down considerably by moving them into a refrigerator at 4 degrees C. In conclusion, the production of ethanol in urine by C. albicans can be prevented by storage of samples in a refrigerator at 4 degrees C or by adding sodium fluoride > or = 1% (w/v). Measuring the ratio of 5HTOL/5HIAA can help to distinguish postsampling production of ethanol from metabolism and excretion processes.
Jones
A W
AW
Department of Forensic Toxicology, University Hospital, Linköping, Sweden.
Hylén
L
L
Svensson
E
E
Helander
A
A
D002176:Candida albicans / Q000187:drug effects / Q000378:metabolism*; D002849:Chromatography, Gas; D003080:Cold Temperature; D000431:Ethanol / Q000032:analysis / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000652:urine; D006917:Hydroxytryptophol / Q000652:urine; D012015:Reference Standards; D012969:Sodium Fluoride / Q000494:pharmacology*; D013048:Specimen Handling / Q000379:methods*; D014556:Urine / Q000737:chemistry / Q000382:microbiology*
D006917:Hydroxytryptophol; D000431:Ethanol; D006897:Hydroxyindoleacetic Acid; D012969:Sodium Fluoride; D005947:Glucose