Test ID: CTB
Mycobacterial Culture
NY State Approved 
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Rapid detection of mycobacteria
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
See Mycobacterial Culture Algorithm in Special Instructions
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Automated Detection of Positive Cultures Followed by Organism Identification with Rapid Methods, Which May Include Nucleic Acid Probes, DNA Sequencing, and Real-Time Polymerase Chain Reaction (PCR) When Appropriate
(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Acid Fast Smear
Bacillus, acid-fast
Culture for TB (Tuberculosis)
Mycobacteria
Nocardia
Smear, Acid Fast Bacilli-AFB
5180-CTB
TB (Tuberculosis) Culture
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Forms: If not ordering electronically, submit a Microbiology Request Form (Supply T244) with the specimen.
Specimen source is required.
Submit only 1 of the following specimens:
Specimen Type: Body fluid
Container/Tube: Sterile container
Specimen Volume: 1 mL
Specimen Type: Bone marrow
Container/Tube: SPS/Isolator System or green top (lithium heparin)
Specimen Volume: Entire collection
Specimen Type: Gastric washing
Container/Tube: Sterile container
Specimen Volume: 10 mL
Collection Instructions: Neutralize specimen within 4 hours of collection with 100 mg of sodium carbonate per 5 to 10 mL of gastric wash.
Specimen Type: Respiratory
Sources: Bronchoalveolar lavage fluid, bronchial washing, or sputum
Container/Tube: Sterile container
Specimen Volume: 3 mL
Collection Instructions: Collect 3 respiratory specimens for acid-fast smears and culture in patients with clinical and chest X-ray findings compatible with tuberculosis. These 3 specimens should be collected at 8- to 24-hour intervals (24 hours when possible) and should include at least 1 first-morning specimen.
Specimen Type: Stool
Container/Tube: Sterile container
Specimen Volume: 5-10 g
Specimen Type: Tissue
Container/Tube: Sterile container
Specimen Volume: 5-10 mm
Collection Instructions: Collect a fresh tissue specimen.
Specimen Type: Urine
Container/Tube: Sterile container
Specimen Volume: 2 mL
Collection Instructions: Collect a random urine specimen.
Specimen Type: Swab
Fresh tissue or body fluid is the preferred specimen type instead of a swab specimen.
Sources: Wound, tissue, or body fluid
Container/Tube: Culture transport swab (non-charcoal) culturette
Specimen Volume: Adequate specimen
Collection Instructions:
1. Before collecting specimen, wipe away any excessive amount of secretion and discharge, if appropriate.
2. Obtain secretions or fluid from source with sterile swab.
3. If smear and culture are requested or both a bacterial culture and mycobacterial culture are requested, collect a second swab to maximize test sensitivity.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | Blood or fixed tissue; specimen in viral transport medium (including but not limited to M4, M5, BD viral transport media, thioglycolate broth); swab sources of nasal, sinus, ear, mouth, throat, or scalp; wood shaft or charcoal swab |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Refrigerated (preferred) | 7 days |
| Ambient | 7 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
From 1985 to 1992, the number of reported cases of tuberculosis increased 18%. This infectious disease still kills an estimated 3 million persons a year worldwide, making it the leading infectious disease cause of death.(1) Between 1981 and 1987, AIDS has disseminated nontuberculous mycobacterial infections; eg,Mycobacteruim intracellulare (MAC). By 1990, the increased number of disseminated nontuberculous mycobacterial infections resulted in a cumulative incidence of 7.6%.(2) In addition to the resurgence of Mycobacterium tuberculosis (MTB), multidrug-resistant MTB (MDR-TB) has become an increasing concern. Laboratory delays in the growth, identification, and reporting of these MDR-TB cases contributed, at least in part, to the spread of the
disease.(3)
The US Centers for Disease Control and Prevention (CDC) have recommended that every effort must be made for laboratories to use the most rapid methods available for diagnostic mycobacteria testing. These recommendations include the use of both a liquid and a solid medium for mycobacterial culture, preferably using an automated system.(3,4)
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.
Negative
Interpretation Provides information to assist in interpretation of the test results
A final negative report is issued after 60 days incubation.
Positive cultures are reported as soon as detected.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Recovery of mycobacteria in the BBL MGIT tube is dependent on the number of organisms present in the specimen, specimen collection methods, methods of processing, and patient factors such as presence of symptoms prior to treatment.
The use of BBL MGIT PANTA antibiotic mixture, although necessary for all nonsterile specimens, may have inhibitory effects on some mycobacteria.
Supportive Data
For over 20 years the gold standard detection system for propagating mycobacteria in vitro has been the Bactec 460 instrument. The radiometric systems uses carbon(14) radio labeled palmitic acid as a substrate, which when metabolized by an organism, produces detectable amounts of carbon labeled carbon dioxide. The MGIT system uses fluorescence technology to detect microbial growth. The Bactec 460 and MGIT systems were compared. A total of 1,963 patient specimens, including 1,519 respiratory tract specimens which required decontamination with sodium hydroxide, and 444 sterile specimens which did not need to be decontaminated, were cultured. A total of 168 cultures grew acid-fast bacilli in 1 or both systems (8.5% positivity rate). The contamination rate for respiratory tract specimens positive in the Bactec 460 was 3.8% and 7.9% in the MGIT. Contamination of sterile specimens was 6.3% in the Bactec 460 and 10.1% in the MGIT. Combined rates were 4.3% for the Bactec 460 and 8.4% for the MGIT. The overall recovery rates for mycobacterial species excluding Mycobacteruim gordonae, were 82.8%, 79.1% and 78.4% for the Bactec 460, MGIT 960, and solid media respectively. Recovery rates for the Bactec 460 and MGIT 960 were considered to be equivalent.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Bloom BR, Murrary CJ: Tuberculosis: commentary on a reemergent killer. Science 1992;257:1055-1064
2. Horsburgh CR, Jr: Mycobacteruim avium complex infection in the acquired immunodeficiency syndrome. N Engl J Med 1991;423:1332-1338
3. Tenover FC, Crawford JT, Huebner RE, et al: The resurgence of tuberculosis: is your laboratory ready? J Clin Microbiol 1993;31:767-770
4. Cohn ML, Waggoner RF, McClatchy JK: The 7H11 medium for the cultivation of mycobacteria. Am Rev Resp Dis 1968;98:295-296
5. Youmans GP: Cultivation of mycobacteria, the morphology and metabolism of mycobacteria. In Tuberculosis. Edited by GP Youmans, Philadelphia, WB Saunders Company, 1979, pp 25-35
6. Kent PT, Kubica GP: Public health mycobacteriology: a guide for the level III laboratory. USDHHS, Centers for Disease Control, Atlanta, GA, 1985
Method Description Describes how the test is performed and provides a method-specific reference
The BBL MGIT Mycobacteria Growth Indicator Tube contains 7 mL of modified Middlebrook 7H9 broth base.(5,6) The complete medium, with OADC Enrichment and PANTA Antimicrobic Mixture, is 1 of the most commonly used liquid media for the cultivation of mycobacteria.
The BACTEC MGIT 960 System is designed for the rapid detection of mycobacteria in clinical specimens. The system includes a liquid culture medium (BBL MGIT Mycobacteria Growth Indicator Tube), a growth supplement (BBL MGIT OADC Enrichment) and an antibiotic mixture (BBL MGIT PANTA). BBL MGIT OADC Enrichment provides substances essential for the growth of mycobacteria. BBL MGIT PANTA contains a mixture of antimicrobial agents used to suppress the growth of contaminating bacteria.
A fluorescent compound is embedded in silicone on the bottom of each of the MGIT broth tubes. This compound is sensitive to the presence of oxygen dissolved in the broth. Initially, the large amount of dissolved oxygen quenches the emissions from the compound and little fluorescence can be detected. Later, actively respiring microorganisms consume the oxygen and allow the fluorescence to be detected.
The automated BACTEC MGIT 960 System monitors the tubes hourly for increasing fluorescence. Analysis of the fluorescence is used to determine if the tube is instrument-positive; ie, the test contains viable organisms. Culture tubes which remain negative for a minimum of 42 days (up to 56 days) and which show no visible signs of positivity are removed from the instrument as negatives.(Youmans GP: Cultivation of mycobacteria, the morphology and metabolism of mycobacteria. In Tuberculosis. Edited by GP Youmans, Philadelphia, WB Saunders Company, 1979, pp 25-35; Kent PT, Kubica GP: Public health mycobacteriology: a guide for the level III laboratory. USDHHS, CDC, Atlanta, 1985)
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.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
Mycobacterial Culture
87116
Mycobacteria Identification by Sequencing
87153 (if appropriate)
Mycobacteria Probe Ident, Solid
87150 (if appropriate)
Mycobacteria Probe Ident, Broth
87150 (if appropriate)
Ident, M. chelonae and M. abscessus, PCR
87149 (if appropriate)
Tissue Processing
87176 (if appropriate)
Mycobacteria Culture, Concentration
87015 (if appropriate)
Susc, Mtb MOP, 1 drug
87190 (if appropriate)
Mtb PZA Confirmation, pcnA sequence
87153 (if appropriate)
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| CTB | Mycobacterial Culture | In Process |
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