Cancer Diagnosis Program | Biorepositories and Biospecimen Research Branch

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Evaluation of the BD Vacutainer Plus Urine C&S Preservative Tubes compared with nonpreservative urine samples stored at 4°C and room temperature.

Author(s): Eisinger SW, Schwartz M, Dam L, Riedel S

Publication: Am J Clin Pathol, 2013, Vol. 140, Page 306-13

PubMed ID: 23955448 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study investigated the effects of storage temperature and preservative on pathogen growth in urine specimens. A total of 110 urine specimens were collected in BD Urine Complete Cups from patients in the emergency department and two unspecified medical units. All specimens were screened upon arrival (5-70 min post collection) in the laboratory using a dipstick and then immediately cultured on trypticase soy (TSA II) with 5% sheep blood agar (SBA) and a MacConkey agar plate. Urine aliquots were stored in a preservative-free BD Vacutainer Urinalysis Plus Conical Urine Tube and BD Vacutainer Plus Urine C&S Preservative Tubes (containing boric acid, sodium formate, and sodium borate) at room temperature and the original collection cup at 4˚C and cultured after 2, 4, 24, and 48 h.

   Summary of Findings:

   Immediately after arrival in the laboratory, 18 specimens did not culture anything, 32 only displayed growth of mixed skin flora (MSF), and 60 grew a pathogen (with or without MSF).  Storage of urine in non-preservative cups at room temperature for 24 h resulted in an increase in the number of specimens containing pathogens from 60 to 80 and a significant increase in the number of cultures with more than 10⁵ CFU/ml of pathogens from 35 to 70. With the increase in pathogenic growth when urine was stored at room temperature without preservatives, there was a decrease in the number of no-growth or MSF-only specimens when stored for 48 h. By contrast, the number of specimens that cultured pathogens only increased from 60 to 61 when non-preserved specimens were refrigerated for 48 h. Similarly, specimens stored at room temperature for 24 h in BDU tubes did not display a significant difference in the number of specimens with a particular pathogen load or total number of specimens that cultured pathogens (59 versus 60). Importantly, the authors report that there was an increase in specimens considered to have clinically significant growth when stored at room temperature without preservative for 24 h or 48 h (P<0.001) and the mean number of total gram-negative bacteria Escherichia coli, and Klebsiella pneumoniae increased significantly per specimen when stored at room temperature for 24 h (P<0.001, P<0.001, and P=0.003; respectively), but no significant differences were observed when stored for up to 48 h at 4˚C or in the presence of preservatives. The pathogens found in urine specimens included gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter cloacae, Pseudomonas aeruginosa, Citrobacter freundii, Klebsiella oxytoca, Shigella species, Raoultella ornithinolytica, Gardnerella vaginalis), gram-positive bacteria (Enterococcus species, Staphylococcus saprophyticus, other coagulase-negative staphylococci, groupB streptococci, and viridans group streptococci), and yeast (Candida albicans, Candida parapsilosis, Candida tropicalis, and Candida species, not further specified).

   Biospecimens

   • Bodily Fluid - Urine

   Preservative Types

   • Other Preservative
   • None (Fresh)

   Diagnoses:

   • Not specified

   Platform:

   Analyte	Technology Platform
   Cell count/volume	Macroscopic observation
   Cell count/volume	Light microscopy
   Cell count/volume	Microbiological assay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage duration	0 h 2 h 4 h 24 h 48 h
   Biospecimen Preservation	Type of fixation/preservation	None (fresh) Refrigeration Boric acid Sodium formate Sodium borate
   Storage	Storage temperature	4˚C Room temperature

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