Reflex Urine Culture

Order Code

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6049

Preferred Specimen

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Collect 4 mL of clean-catch, midstream urine and transfer it into a urine culture preservative tube (gray-top Boricult®).

Ensure the tube is filled to the marked fill line. Store and transport at room temperature.

Note: For catheterized urine or suprapubic aspirate collections, please order test 6094: Culture, Urine, Catheter.

ContainerType

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Urine transport (gray top boricult) tube

Alternate Specimen Requirements

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Urine collected in a sterile container, stored refrigerated

Urine collected in preservative systems equivalent to the gray-top Boricult®

Minimum Volume

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4 mL urine in transport tube, or
0.5 mL refrigerated urine in sterile urine cup

Transport Temperature

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Room temperature

Expected Turnaround Time

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4 days

Specimen Stability

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Unpreserved urine:

• Room temperature: Unacceptable
• Refrigerated: Stable for 24 hours
• Frozen: Unacceptable

Preserved urine (e.g., Boricult®):

Frozen: Unacceptable

Room temperature: Stable for 48 hours

Refrigerated: Stable for 48 hours

Methodology

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Standard urine culture methodology sensitivity is not generally performed on organisms recovered in low number or in mixed urogenital flora

Rejection Criteria

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• Frozen samples
  contaminated samples
  swabs
  unpreserved samples submitted greater than 24 hours
  following collection.
  preserved samples submitted greater than 48 hours
  following collection.
  expired transport media
  non-sterile containers
  samples submitted in leaking containers
  samples submitted in viral transport media
  samples submitted in urinalysis preservative tubes

Overview

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Bacterial urinary tract infections (UTIs) are a frequent cause of morbidity and may present with or without symptoms. Common clinical signs include dysuria, abdominal or rectal pain, hematuria, fever, and vomiting.
The organisms most frequently associated with uncomplicated UTIs (Pezzlo, 2014) include:

Gram-Negative Bacteria (prevalence varies by population and setting):

• Escherichia coli – 70% to 90%
• Klebsiella pneumoniae – 2% to 6%
• Proteus mirabilis – 2% to 4%
• Enterobacter species – 0% to 1%
• Pseudomonas aeruginosa – 0% to 1%

Gram-Positive Bacteria:

• Staphylococcus saprophyticus – 5% to 20%
• Enterococcus species – 1% to 2%
• Streptococcus agalactiae – 0% to 1%
• Staphylococcus aureus – 0% to 1%

Fungi:

• Candida species – 0% to 1%

Urine culture remains the gold standard for diagnosing UTIs. Reliable interpretation depends heavily on collecting a clean, uncontaminated specimen.

Clinical Significance

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Isolate and identify potentially pathogenic organisms causing urinary tract infection

Interpretative Information

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Urine cultures often yield mixed flora, sometimes involving multiple organisms in varying quantities. To support accurate diagnosis, laboratories follow defined criteria to determine which isolates should be worked up and undergo antimicrobial susceptibility testing (AST). These criteria also help manage testing resources and ensure clinical relevance.

Factors considered by the testing laboratory may include:

Collection method and risk of contamination (e.g., clean-catch vs. catheterized or suprapubic aspirate)

Colony count thresholds for common skin flora versus potential uropathogens

Relative abundance of pathogens versus contaminants

For clean-catch urine, most labs consider ≥10⁴ CFU/mL as the threshold for clinical significance. However, this threshold can vary depending on patient demographics, specimen source, and guidelines followed (e.g., ASM, IDSA, CLSI).

For invasively collected specimens (e.g., catheter or suprapubic aspirate), ≥10³ CFU/mL is often considered significant.

In general, a urine culture is considered clinically relevant when:

The organism is a recognized uropathogen

It is isolated at significant concentrations (typically >10³ or >10⁴ CFU/mL)

No more than two or three uropathogens are present in the culture

Yeast is typically reported descriptively (e.g., “Yeast present”) rather than quantified.

Clinically significant infections typically involve one or two pathogens.

Limitations

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• Forced fluids dilute the urine and may cause reduced colony counts.
• Cultures of specimens from Foley catheters yield multiple organisms with high colony counts and usually represent colonization of the catheter and not true significant bacteriuria. Foley catheter specimens should not be submitted.
• Use of urinalysis test results to predict which specimens should be cultured is fraut with problems, not the least of which is the fact that a definition of such a clinically relevant, efficient, and reliable urinalysis result has yet to be determined.

References

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Alias

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• UA culture
• Urine culture

Test Setup Days

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Daily set up PM shift

CPT

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87086 Limited Coverage Test For Medicare.
Advance Beneficiary Notice Of Non-Coverage (ABN) Required
If Diagnosis Is Not Covered.
LOINC: 630-4

Reference Range

NO GROWTH
SMALL QUANTITIES OF UROGENITAL FLORA USUALLY REFLECT
IMPROPER COLLECTION TECHNIQUE

UNIT CODE	UNIT CODE NAME	ANALYTE	GENDER	AGE	REFERENCE RANGE	Units of Measure
6049	URINCUL				NO GROWTH