Test Catalog

Test ID: URNS    
Bacterial Culture, Aerobic, with Antimicrobial Susceptibilities, Urine

Method Description Describes how the test is performed and provides a method-specific reference

The urine specimen is inoculated onto sheep blood agar and eosin methylene blue agar using a calibrated loop. Following 18 to 24 hours of incubation, semiquantitative colony counts are determined and pathogens or possible pathogens are identified using one or a combination of the following techniques: commercial identification strips or panels, matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry, conventional biochemical tests, carbon source utilization, real-time polymerase chain reaction (PCR), and nucleic acid sequencing of the 16S ribosomal RNA (rRNA) gene. Cultures with fewer than 10,000 cfu/mL of a single species are reported as "Organism present <10,000 cfu/mL." The presence of commensal flora of the urethra (contaminants) and mixed cultures of organisms present in colony counts below 10,000 cfu/mL are reported as "mixed flora."(Chan WW: Urine cultures. In Clinical Microbiology Procedures Handbook. Vol 1. Fourth edition. Edited by AL Leber. Washington DC, ASM Press, 2016, Section 3.12)


When antimicrobial susceptibility testing (AST) is performed, an agar dilution method is used for routine testing. The antimicrobial is added to agar in various concentrations depending upon levels attainable in serum, urine, or both. A standardized suspension of the organism is applied to the agar plates, which are incubated for 16 to 18 hours at 35 degrees C. Complete inhibition of all but one colony or a very fine residual haze represents the end-point.(CLSI. Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Standard. 11th edition. CLSI standard M07. Wayne, PA: Clinical and Laboratory Standards Institute; 2018)

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.

Monday through Sunday

Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

2 days

Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Clinic Laboratories until the release of the test result

5 days

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 day

Performing Laboratory Location Indicates the location of the laboratory that performs the test