title: Laboratory assessment of physical and chemical methods of preserving urine specimens.
abstract: Three methods of preserving simulated specimens of urine were studied with six test strains of bacteria. Viable counts were measured by a surface viable count and by the filter-paper-strip method during a holding period of 72 hours. Refrigeration at approximately 4 degrees C was effective and reliable. Boric acid (1-8%) at room temperature was toxic for the strain of Escherichia coli at a density of 10(7) cfu/ml but this may not be significant at the higher concentration of bacterial cells often found in clinical specimens. NaCl-polyvinylpyrrolidone (PVP) solutions containing PVP of mol. wt 44 000 or 700 000 were not effective; they were toxic for the Gram-negative strains and did not retard the growth of Micrococcus subgroup 3. The two methods of measuring viable counts were compared for specimens held under different conditions; the specificity of the filter-paper-strip method was high but the sensitivity was low when many of the specimens contained approximately 10(5) cfu/ml.
mesh_terms: D001419:Bacteria / Q000187:drug effects / Q000302:isolation & purification; D001888:Boric Acids / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects; D006801:Humans; D008297:Male; D011205:Povidone / Q000494:pharmacology; D011309:Preservation, Biological; D012034:Refrigeration; D012965:Sodium Chloride / Q000494:pharmacology; D014556:Urine / Q000382:microbiology
chemical_list: D001888:Boric Acids; D012965:Sodium Chloride; D011205:Povidone