SPUT - Performance: Bacterial Culture, Aerobic, Respiratory

Test Catalog

Test Name

Test ID: SPUT    
Bacterial Culture, Aerobic, Respiratory

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

All sputum and induced sputum specimens are screened microscopically by Gram stain to avoid culturing specimens that do not represent lower respiratory secretions; specimens with more than 25 squamous epithelial cells per low-power field will not be cultured.


Lower respiratory specimens are inoculated onto sheep blood agar, eosin methylene blue agar, and chocolate agar, and are incubated for 48 hours. The following organisms are identified and reported: Streptococcus pneumoniae; Streptococcus pyogenes; other beta-hemolytic Streptococcus species. groups B, C, and G; Haemophilus species; Staphylococcus aureus; Moraxella catarrhalis; Neisseria meningitidis; gram-negative bacilli; and predominant yeast; or Corynebacterium pseudodiphtheriticum/propinquum. Other organisms are classified as usual oropharyngeal flora.(York MK, Gilligan P, Alby K: Lower respiratory tract cultures. In Clinical Microbiology Procedures Handbook, Vol 1, Fourth edition. Edited by AL Leber. Washington DC, ASM Press, 2016, Section 3.11.2.)


When antimicrobial susceptibility testing 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 1 colony or a very fine residual haze represents the end-point.(CLSI. Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard-Tenth Edition. CLSI document M07-A10. Wayne, PA: Clinical and Laboratory Standards Institute; 2015)

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; Continuously

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.

4 days

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

6 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 The location of the laboratory that performs the test