Test Catalog

Test ID: TBIDS    
Culture Referred for Identification, Mycobacterium and Nocardia with Antimicrobial Susceptibility Testing, Varies

Useful For Suggests clinical disorders or settings where the test may be helpful

Rapid identification to the species level and susceptibility testing for Mycobacterium species, Nocardia species, and other aerobic actinomycete genera and species from pure culture isolates

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the reflex antimicrobial susceptibility test will be performed at an additional charge. All mycobacteria and Nocardia (including aerobic actinomycetes) submitted will be identified and billed as appropriate.


Nucleic acid probes used for identification, when applicable, include those for Mycobacterium avium-intracellulare complex, M gordonae, and M tuberculosis complex. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF MS) and/or 16S rDNA sequencing is used for identification, when applicable, for slowly and rapidly growing Mycobacterium species and aerobic actinomycetes (including Nocardia species and Streptomyces species). The M tuberculosis complex can be further identified to the species level upon request, using a separate rapid PCR test. Minimum inhibitory concentration (MIC) determination by either the microtiter broth dilution method or critical concentration testing by broth dilution will be automatically performed as appropriate after species identification.


See Culture Referred for Identification and Susceptibility for Mycobacterium and Nocardia Algorithm in Special Instructions.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

There are nearly 200 recognized species of mycobacteria and more than 100 Nocardia species. Many are human pathogens and, therefore, identification to the species level is important to help guide patient care. In addition, there are other aerobic actinomycete genera that can be human pathogens including, but not limited to, Tsukamurella, Rhodococcus, and Gordonia species.


Nucleic acid hybridization probes are utilized that identify specific ribosomal RNA sequences of Mycobacterium tuberculosis complex, M avium complex, and M gordonae. Other Mycobacteria species, Nocardia species, and other aerobic actinomycete genera are identified using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF MS) or nucleic acid sequencing of a 500-base pair region of the 16S ribosomal RNA gene.


After identification, antimicrobial susceptibility testing is performed following Clinical and Laboratory Standards Institute (CLSI) M24 guidelines using either broth dilution or critical concentration methods as appropriate for the species.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Not applicable

Interpretation Provides information to assist in interpretation of the test results

Organisms growing in pure culture are identified to the species level whenever possible.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

If the organism is received in mixed culture or contaminated, the report may be delayed or identification may not be possible.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Pfyffer GE: Mycobacterium: general characteristics; laboratory detection, and staining procedures. In Manual of Clinical Microbiology. 11th edition, Vol 1. Edited by JH Jorgensen, MA Pfaller. Washington DC, ASM Press. 2015, pp 536-569

2. Clinical and Laboratory Standards Institute: Susceptibility Testing of Mycobacteria, Nocardiae, and Other Aerobic Actinomycetes; Approved Standard. Second edition. CLSI document M24-A2 (ISBN 1-56238-746-4), Clinical and Laboratory Standards Institute, 950 West Valley road, Suite 2500, Wayne, Pennsylvania 19087 USA, 2011

Special Instructions Library of PDFs including pertinent information and forms related to the test