Test : Sputum Mycobacteria culture
Indications : The emergence of
M. tuberculosis and M. avium- induced intracellular infections in those with acquired immunodeficiency syndrome (
AIDS) has been increasing. The test is ordered when the doctor suspects TB or a related infection in a patient.
An early morning sample of expectorated or induced sputum is collected.
Most often, you will be asked to cough with force and spit out the sputum into a sterile container. To facilitate sputum production you may have to drink plenty of fluids the day before the sample collection. If sputum does not come out naturally, it may have to be induced through inhalation using a nebulizer.
The collected sputum sample is taken to the laboratory to be grown in a petri dish containing special media that enables the growth of the
TB bacterium.
Physiology : Mycobacterial culture is a laboratory test that is done to detect the presence of
Mycobacterium tuberculosis, the bacterium that causes tuberculosis.
Mycobacterium tuberculosis usually affects the lungs, but can cause damage to other body parts too. It is contagious and spreads from an affected person, to others, through air. A person with a weak immune system is more likely to be afflicted with the TB bacterium. Many individuals have latent tuberculosis, which is symptom less. In one tenth of those with latent disease, there is a progression to the active form, which can be fatal if left untreated.
Normal Range : No growth
Interpretation : Normal
Negative -No growth of
Mycobacterium tuberculosis or similar bacteria in the culture dish.
Abnormal
Positive -Growth of
Mycobacterium tuberculosis or similar bacteria is seen in the laboratory culture. This indicates TB, and the patient needs immediate medical attention.
Sample : Sputum, tracheal aspiration, bronchoscopy specimen, transtracheal aspirate.
Test Method : Culture on slective medium - Lowenstein-Jensen and Middlebrook 7H11.
Related Tests : Acid fast stain, Bronchial washing, Bronchoalveolar lavage, Nocardia culture, Sputum culture, Viral culture.
References :
1. http://www.nlm.nih.gov/medlineplus/ency/article/003740.htm
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