Test Catalog

Test ID: CFRCS    
Bacterial Culture, Cystic Fibrosis with Antimicrobial Susceptibilities, Varies

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

Standard media (5% sheep blood, chocolate, and eosin methylene blue: [EMB] agar plates) used for respiratory cultures are inoculated. In addition, 2 selective agar plates are utilized to enable isolation of slower growing pathogens that may be easily overgrown by usual flora and the longstanding colonization by Pseudomonas aeruginosa. Burkholderia cepacia Selective Agar plate is used for the isolation of B cepacia complex, which includes 20 distinct species. Isolates of B cepacia will be forwarded to the University of Michigan's CFF Research Testing and Repository for genotyping. (There is no charge for this shipping/testing). A chromogenic Staphylococcus aureus agar is used to enhance the isolation of S aureus. Finally, a second chocolate blood agar plate is incubated in an anaerobic atmosphere. The anaerobic atmosphere allows for detection of Haemophilus species that may otherwise be overgrown by P aeruginosa. Pathogens or possible pathogens are identified using 1 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.(Gilligan P, Alby K, York MK: Respiratory Cultures from Cystic Fibrosis Patients. In Clinical Microbiology Procedures Handbook, Vol 1, Fourth edition. Edited by AL Leber. Washington DC, ASM Press, 2016, Section 3.11.3)


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.(Clinical and Laboratory Standards Institute: Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically. 11th edition. CLSI standard M07. Wayne, PA, 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.

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.

5 days

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

12 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