Boric acid preservation of urine samples.
Author(s): Porter IA, Brodie J
Publication: Br Med J, 1969, Vol. 2, Page 353-5
PubMed ID: 5768462 PubMed Review Paper? No
Purpose of Paper
This paper investigated the effects of boric acid or dip-inoculum transport medium preservation, shipping on ice, and an inoculation delay of three days at room temperature.
Conclusion of Paper
Although the number of significant culture results increased when unpreserved urine was stored for three days at room temperature before inoculation, it did not increase for boric-acid preserved urine. Further, results were similar in dip-inoculum transport medium and boric acid- preserved urine when analyzed immediately after arrival in the laboratory, but less growth was observed for 2 of 40 boric acid-preserved specimens. Importantly, unpreserved urine was more likely to yield a significant culture result than preserved urine, even when analyzed immediately after arrival in the laboratory.
Studies
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Study Purpose
This study investigated the effects of preserving urine from hospitalized patients with boric acid or dip-inoculum transport medium (DITM) on urine culture results obtained immediately or after three days at room temperature. One hundred midstream urine specimens were collected from hospitalized patients and aliquots were transferred into sterile and dip-inoculum transport medium containers and mailed in envelopes at ambient temperature (1 to 2-day delay). An additional 40 specimens were aliquoted into sterile cups, containers with 0.5 g boric acid, and dip-inoculum transport medium containers and mailed in envelopes at ambient temperature. Upon arrival, the DITM specimen was incubated at 37˚C for 24 h and the sterile urine and boric acid preserved-specimens were streaked on culture plates immediately and again after three days at room temperature. Cultures were analyzed after 24 h at 37˚C.
Summary of Findings:
Colony counts were higher in 24 of the 140 sterile cup specimens than matched DITM specimens, lower in 5 of the specimens, and comparable in the remaining 111 specimens. Boric acid-preserved specimens had lower colony counts than DITM in 2 of 40 specimens, but comparable counts in the remaining 38. Storing boric acid-preserved specimens for an additional three days resulted in two significant results in boric acid being characterized as doubtful significance, but did not change the number of non-significant cultures. In contrast, 14 of 40 unpreserved specimens were classified as significant when stored at room temperature for three days.
Biospecimens
Preservative Types
- None (Fresh)
- Other Preservative
Diagnoses:
- Other diagnoses
- Not specified
Platform:
Analyte Technology Platform Cell count/volume Microbiological assay Cell count/volume Light microscopy Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Time at room temperature 0 days
3 days
Biospecimen Preservation Type of fixation/preservation Boric acid
DITM
None (fresh)
-
Study Purpose
This study investigated the effects of transporting by plane on ice rather than mailing at room temperature, boric acid preservation, and a 3-day room temperature delay on urine culture results from hospitalized patients. Midstream urine specimens were collected from 65 hospitalized patients; two aliquots were transferred into sterile containers and one into containers with 0.5 g boric acid. The boric acid-preserved urine and one of the aliquots of unpreserved urine were mailed in envelopes at ambient temperature (1 to 2-day delay) while the other unpreserved specimen was placed on ice (maintained 9-15˚C) and transported by plane. The specimens transported by air were cultured upon arrival (approximately 6 h after collection) and again three days later. The mailed specimens were cultured upon their arrival and again three days later.
Summary of Findings:
Boric acid specimens shipped on ice had more growth in two specimens and less growth in one specimen compared to mailed specimens. Importantly, both cases showing an increase in growth in the specimen shipped on ice were delayed such that the transit time was one day rather than 6 h. In contrast, 25 of 65 specimens showed increased growth when shipped unpreserved at ambient temperature compared to those shipped with boric acid. When urine specimens were stored at room temperature for three days after arrival at the laboratory, one boric acid-preserved specimen that was positive became negative, 42 negative unpreserved specimens became positive, and seven negative unpreserved specimens shipped on ice became positive.
Biospecimens
Preservative Types
- Other Preservative
- None (Fresh)
Diagnoses:
- Other diagnoses
- Not specified
Platform:
Analyte Technology Platform Cell count/volume Light microscopy Cell count/volume Microbiological assay Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Preservation Type of fixation/preservation Boric acid
Refrigeration
None (fresh)
Storage Time at room temperature 0 days
3 days
Storage Specimen transport duration/condition One ice for ~6 h
Ambient temperature for 1-2 days
Storage Between site transportation method Air courier
Mailed
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Study Purpose
This study investigated the effects of preservation with boric acid and a 3-day delay to culture on growth results in urine from outpatients. Mid-stream urine was collected from 130 patients at a general clinic and split into a container with boric acid and one without. The matched urine specimens were mailed 42 miles (average transport of 1 day) in the same envelope. Specimens were cultured immediately and again after three days at room temperature.
Summary of Findings:
When cultured immediately upon arrival, significant growth occurred in an additional 22 of 130 unpreserved specimens than boric acid preserved specimens and doubtful significant growth occurred in an additional seven specimens. When specimens were stored at room temperature for three days before culture, results for boric acid-preserved specimens were unchanged, but an additional 44 negative specimens became positive in the unpreserved specimen. Consequently, 75 specimens were positive in unpreserved specimens but negative in matched boric acid-preserved specimens when culturing was delayed three days.
Biospecimens
Preservative Types
- Other Preservative
- None (Fresh)
Diagnoses:
- Other diagnoses
- Not specified
Platform:
Analyte Technology Platform Cell count/volume Light microscopy Cell count/volume Microbiological assay Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Time at room temperature 0 days
3 days
Biospecimen Preservation Type of fixation/preservation Boric acid
None (fresh)