Mycobacteria other than tuberculosis: Mycobacteria other than tuberculosis (MOTT) are mycobacterial species that my cause human disease but do not cause tuberculosis. Every year in the United States approximately two people per 100,000 population develop infections caused by theses lesser-known “cousins” of tuberculosis. In fact, data suggest that there may be rising numbers of cases in certain parts

Of the country. Mycobacteria are a diverse group of rod-shaped bacteria that include more than 100 different species. Except for Mycobacterium tuberculosis (which causes the disease tuberculosis (TB)) and Mycobacterium leprae (which causes leprosy), most mycobacteria live in the soil and water in both rural and urban settings throughout the world. They can be found in aerosols, rivers and swamps, in treated city water, public swimming pools, hot spas, humidifiers, aquariums, garden soils, food, and many other places. Because they are protected by their waxy lipid-rich cell wall, mycobacteria are resistant to disinfectants and water Treatment measures.

There is not a standard naming convention for this group of microorganisms. They may be referred to as nontuberculous mycobacteria (NTM), mycobacteria other than tuberculosis (MOTT), atypical mycobacteria, and/or environmental mycobacteria. Almost half of the NTM species identified are associated with opportunistic infections in animals and humans, and several have caused sporadic outbreaks. NTM are acquired through environmental exposure to water, aerosols, soil, and dust – through inhalation, ingestion, and through breaks in the skin due to injuries, surgical procedures.Unlike M. tuberculosis, they are not passed from person-to-person with the exception of M. leprae, which requires extended close contact, such as with an infected family member.Most NTM reproduce slowly, which allows the infection to emerge weeks, months, or even years after the initial exposure.

Anyone can become infected, but people with suppressed immune systems (such as those with HIV/AIDS and transplant recipients), people with pre-existing lung damage (such as from smoking and previous tuberculosis) and those with lung diseases (such as emphysema or cystic fibrosis) are most likely to be affected. NTM infections can be challenging and time-consuming to treat since the organisms may be resistant to commonly prescribed antibiotics.

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis bacteria. TB primarily targets the lungs but may affect any area of the body such as the urinary tract, central nervous system, bones and/or joints, other organs, abdominal area, or lymph nodes. A tuberculosis infection that has spread through the blood to various organs of the body is termed miliary tuberculosis. With respiratory infections, TB is spread through the air from person to person through droplets of respiratory secretions such as sputum or aerosols released by coughing, sneezing, laughing, or breathing. Most of those who become infected with M. tuberculosis manage to confine the mycobacteria to a few cells in their lungs, where they stay alive but in an inactive form. This latent TB infection does not make the person sick or infectious and, in most cases, it does not progress to active tuberculosis. The goals with treatment are to resolve the nontuberculous mycobacteria (NTM) infection in the affected person and prevent further damage to tissues and organs. If there is evidence of widespread infection due to a common exposure, the medical community investigates the outbreak to find and eliminate the source of the infection(s). With M. leprae, treatment is also necessary to prevent the spread of the infection.


The treatment of NTM infections usually involves more than one antibiotic for a prolonged period of time. The length of treatment depends on the results of the AFB smears and cultures used to monitor the effectiveness of treatment. A few of the NTM infections, such as those caused by M. ulcerans, are best treated through surgical debridement of the skin ulcers (removal of damaged infected skin) to prevent further spread of the infection. In cases where the infection is localized, such as an infected lymph node, the infected tissue may be surgically removed.


Although symptoms often resolve after several weeks, it is crucial that those affected continue to take their drugs for the time period recommended by their doctor. There are often a large number of mycobacteria to kill and it may take several months or longer to make sure that all of them have been eradicated. People with NTM infections should follow their doctor’s recommendations for the best treatment for their specific condition.


Symptoms associated with nontuberculous mycobacteria (NTM) infections depend on which part(s) of the body are involved. Pulmonary infections may cause TB-like symptoms, including:


  • Chronic cough, sometimes with bloody sputum
  • Fever
  • Chills
  • Weight loss
  • Weakness


Skin-related NTM infections may cause persistent sores, boils, ulcers, and granulomas. Those affecting lymph nodes may cause inflammation in the node.


Methodology: Taqman Real time PCR assay

Clinical Use:

  • The identification of Mycobacterium to the species level is important because of the clinical significance; some species are pathogenic while others are not
  • Knowledge of species is also critical in order to provide adequate patient management because; specific antimycobacterial drugs are required against different pathogenic Identify
  • MTB viral load quantitation/ Detection for epidemiologic and prognostic purposes
  • Assess bacterial response to treatment as measured by changes in the MTB DNA levels
  • The molecular detection of the organism’s genetic material (DNA/RNA) may be performed on the primary specimen and also used as a means to identify the species of mycobacteria once the bacteria are grown in culture.

Screening: Centers for Disease Control recommendations

  • NAAT (nucleic acid amplification test) be performed on at least one sample from someone with signs and symptoms of TB.
  • Patient has AIDS & HIV-positive persons
  • Immunocompromised persons (meaning people with weakened immune systems),

Such as organ and bone marrow transplant recipients, cancer patients, patients receiving immunosuppressive drugs

Performed:  Every day
Reported: 2-3 days

Specimen required: C.S.F. Plueral fluid, Synovial fluid, Sputum, Pus, tissue, bronchial lavage, urine, endometrium, Culture Cells, biopsy, Fine Needle Aspirations, ascites. Cerebrospinal fluid or body tissue (biopsy) .Stability collection to initiation of testing On Cells: Ambient: 6 hours: Refrigerated: 4 0C.

NOTE-Blood should only be sent in cases of miliary or disseminated tuberculosis.


Storage/Transport Temperature: Frozen-20 0C. Refrigerate specimens at 2°C-4°C.

Unacceptable Conditions
:  Heparinized specimens, Hemolysis sample, Quantity not sufficient for analysis, specimen grossly contaminated, specimen too old, frozen whole blood specimen, specimen leaky or tube broken.


Interpretation:  Specific amplification curve for MTC complex group indicate presence of MTC in given sample. Same way Specific Amplification curve for MOTT indicate presence of MOTT in given sample.Whereas no amplification in MTC and MOTT Chanels indicates absence of MTC/MOTT in this test. Amplification of internal control indicates no PCR inhibition. This test detects MTC along with mycobacterium other than tuberculosis. This test can detect and Differentiate MTC/MOTT DNA over the range 80-109 copies/mL. However this does not mean that lower copies or higher copies cannot be detected. The lower copies can be detected in some cases. This is a limitation of the currently available extraction systems.A negative result does not preclude the presence of MTB/MOTT infection because results depend on adequate/proper patient sample storage and transportation, absence of inhibitors and sufficient DNA to be detected.

NOTE-The result of this test must always be correlated with clinical status and history of the patient and other relevant data and should not be used alone for the interpretation.

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