AFB Smear and Culture : labtest

Why Get Tested?
To help identify a mycobacterial infection; to diagnose tuberculosis (TB); to monitor the effectiveness of treatment
When to Get Tested?
If you have symptoms, such as a chronic cough, weight loss, fever, chills, and weakness, that may be due to TB or another mycobacterial infection; if your doctor suspects that you have active TB; if your doctor wants to monitor the effectiveness of TB treatment
Sample Required?
Usually, three sputum samples are collected early in the morning on different days. If the patient is unable to produce sputum samples, a bronchoscope may be used to collect fluid during a procedure called a bronchoscopy. In children, gastric washings/aspirates may be collected. Depending on symptoms, urine, cerebrospinal fluid (CSF), other body fluids, or biopsied tissue samples may be submitted for culture.

How is it used?
AFB smears and cultures are used to determine whether you have an active Mycobacterium tuberculosis infection, an infection due to another member of the Mycobacterium family, or TB-like symptoms due to another cause. They are used to help determine whether the TB is confined to the lungs (pulmonary) or has spread to organs outside the lungs (extrapulmonary). They are ordered to identify M. tuberculosis and determine the most effective antimicrobial agents to treat the infection. M. tuberculosis may be resistant to one or more drugs commonly used to treat TB. If the bacteria are resistant to more than one or the primary drugs used for therapy, the organisms are called multi-drug resistant TB (MDR TB), and if the organisms are resistant to multiple first and second lines of therapy, they are called extensively drug-resistant tuberculosis (XDR TB). AFB cultures can be used to monitor the effectiveness of treatment and can help determine when a patient is no longer infectious.
Since TB is transmitted by airborne droplets from respiratory secretions, it is a public health risk. It can spread in confined populations, such as correctional facilities, nursing homes, and schools. Those who are very young, elderly, or have diseases and conditions such as AIDS that compromise their immune systems tend to be especially vulnerable. AFB smears and cultures can help track and minimize the spread of TB in these populations and help determine the effectiveness of treatment.

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