Test Id : CTB

When this test is ordered, a reflex test may be performed at an additional charge.

The following algorithms are available:

-Mycobacterium and Nocardia Culture Algorithm

-Meningitis/Encephalitis Panel Algorithm

1. Specimen source is required.

2. Alert the laboratory if Mycobacterium genavense is suspected, as this species requires addition of mycobactin J to the culture medium for optimal growth and recovery.

Submit only 1 of the following specimens:

Specimen Type: Body fluid

Container/Tube: Sterile container

Specimen Volume: 1.5 mL

Specimen Type: Bone marrow

Container/Tube: Sterile container, or green top (lithium or sodium 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, sputum

Container/Tube: Sterile container

Specimen Volume: 3 mL

Collection Instructions:

1. Collect 3 respiratory specimens for acid-fast smears and culture in patients with clinical and chest X-ray findings compatible with tuberculosis.

2. 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

Supplies: Stool Collection Kit, Random (T635)

Container/Tube: Sterile container

Specimen Volume: 5 to 10 g

Specimen Type: Tissue

Container/Tube: Sterile container

Specimen Volume: 5 to 10 mm

Collection Instructions: Collect a fresh tissue specimen.

Specimen Type: Urine

Container/Tube: Sterile container

Specimen Volume: 20 to 50 mL

Collection Instructions: Collect a random urine specimen.

Fresh tissue or body fluid is the preferred specimen type instead of a swab specimen. Recovery of mycobacteria from swabs is generally very low yield.

Specimen Type: Swab

Sources: Wound, tissue, or body fluid

Container/Tube: Culture transport swab (noncharcoal) culturette, or Eswab

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.

• Mycobacterium and Nocardia Culture Algorithm
• Meningitis/Encephalitis Panel Algorithm

If not ordering electronically, complete, print, and send 1 of the following:

-Microbiology Test Request (T244)

-General Request (T239)

See Specimen Required

Detection and identification of Mycobacterium species, Nocardia species, and other aerobic actinomycetes

When this test is ordered, a reflex test may be performed at an additional charge.

The following algorithms are available:

-Mycobacterium and Nocardia Culture Algorithm

-Meningitis/Encephalitis Panel Algorithm

Mycobacteria species are responsible for significant morbidity and mortality in both immunocompromised and immunocompetent hosts. Mycobacterium tuberculosis is the causative agent of tuberculosis, and it kills nearly 2 million people in the world each year. Nontuberculous mycobacteria such as Mycobacterium avium complex and Mycobacterium abscessus cause a variety of infections (eg, respiratory, skin, and soft tissue) and are important to detect and correctly identify in order to aid in clinical decision making. There are approximately 200 recognized species of mycobacteria and identification of these organisms to the species level is often required to help guide appropriate therapy. Although there are direct detection methods available for M tuberculosis, growth of the organism on culture media is still necessary to allow for antimicrobial susceptibility testing. At this time, direct molecular detection methods are lacking for the nontuberculous mycobacteria and growth in culture is critical for identification and antimicrobial susceptibility testing.

Nocardia species and other aerobic actinomycetes (eg, Tsukamurella species, Gordonia species, Rhodococcus species) are also important causes of disease and isolation on culture media is important to facilitate identification and antimicrobial susceptibility testing. Nocardia and the other aerobic actinomycetes grow well on mycobacterial medium, and therefore, ordering a mycobacterial culture is recommended when infection with this group of organisms is suspected.

Negative

A final negative report is issued after 42 days of incubation.

Positive cultures are reported as soon as detected.

Recovery of mycobacteria is dependent on the number of organisms present in the specimen, specimen collection methods, methods of processing, and patient factors such as the use of anti-mycobacteria therapy.

The use of BBL MGIT PANTA antibiotic mixture, although necessary for all nonsterile specimens, may have inhibitory effects on some mycobacteria.

The Bactec 460 and Bactec MGIT 960 systems were compared. A total of 1963 patient specimens were cultured, including 1519 respiratory tract specimens that required decontamination with sodium hydroxide and 444 sterile specimens that did not need to be decontaminated. A total of 168 cultures grew acid-fast bacilli in 1 or both systems (8.5% positivity rate). The contamination rate for positive respiratory tract specimens was 3.8% in the Bactec 460 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 Mycobacterium 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.

1. Martin I, Pfyffer GE, Parrish N: Mycobacterium: General characteristics, laboratory detection and staining procedures. In: Carroll KC, Pfaller MA, Landry ML, et al, eds. Manual of Clinical Microbiology. 12th ed. Vol 1. ASM Press;2011:472-5022.

2.Banaei N, Musser KA, Salfinger M, Somoskovi A, Zelazny AM. Novel assays/applications for patients suspected of mycobacterial diseases. Clin Lab Med. 2020;40(4):535-552. doi:10.1016/j.cll.2020.08.010

3. Lafont E, Conan PL, Rodriguez-Nava V, Lebeaux D. Invasive nocardiosis: Disease presentation, diagnosis and treatment - old questions, new answers? Infect Drug Resist. 2020;13:4601-4613. doi:10.2147/IDR.S249761

The BACTEC MGIT 960 System is a broth system designed for the rapid detection of mycobacteria in clinical specimens. Mycobacteria Growth Indicator Tubes (MGIT) are incubated for up to 42 days and growth is evaluated with mycobacteria identified as soon as a MGIT signals positive on the instrument.

In addition to the MGIT tube, Middlebrook 7H10/7H10S agar biplates are inoculated and incubated at 37 degrees C for 42 days. Growth from positive MGITs or agar plates is identified using a variety of techniques as appropriate including rapid polymerase chain reaction, matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, or 500 basepair 16S rRNA gene sequencing.

The Mycobacterium tuberculosis complex will be identified to the species level upon request using rapid polymerase chain reaction.(Martin I, Pfyffer GE, Parrish N: Mycobacterium: General characteristics, laboratory detection and staining procedures. In: Carroll KC, Pfaller MA, Landry ML, et al, eds. Manual of Clinical Microbiology. 12th ed. Vol 1. ASM Press; 2019:558-575; Halse TA, Escuyer VE, Musser KA: Evaluation of a single tube multiplex real-time PCR for differentiation of the Mycobacterium tuberculosis complex in clinical specimens. J Clin Microbiol. 2011;49[7]:2562-2567. doi:10.1128/JCM.00467-11)

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• Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
• Prospective clients should contact their account representative. For assistance, contact Customer Service.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

87116-Mycobacterial Culture

87015-Mycobacteria Culture, Concentration (if appropriate)

87118-Id MALDI-TOF Mass Spec AFB (if appropriate)

87150-Id, Mtb Speciation, PCR (if appropriate)

87153-Mycobacteria Identification by Sequencing (if appropriate)

87176-Tissue Processing (if appropriate)

87150- Id, MTB complex Rapid PCR (if appropriate)