Description
Overview: Once a patient tests positive for Mycobacterium tuberculosis, it is vital to know if the standard medication will work. The Acid Fast Susceptibility – 5 Drugs panel tests the isolated bacteria against the primary arsenal of anti-TB antibiotics. The BACTEC MGIT (Mycobacteria Growth Indicator Tube) liquid culture system is used to provide results significantly faster (often weeks earlier) than older solid media methods.
The “5 Drugs” (First-Line Panel):
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Isoniazid (H)
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Rifampicin (R)
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Ethambutol (E)
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Streptomycin (S)
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Pyrazinamide (P) (Included in the 5-drug panel to ensure complete first-line coverage).
Clinical Significance:
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Standard of Care: This is the essential first step in guiding TB therapy. If the bacteria are susceptible to all 5 drugs, the patient can be treated with the standard, shorter-course regimen.
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Detecting MDR-TB: If resistance is detected (especially to Isoniazid and Rifampicin), the patient is diagnosed with Multi-Drug Resistant TB (MDR-TB), and the “10 Drug Panel” (Second Line) becomes necessary to find alternative treatments.
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Preventing Spread: identifying resistance early prevents the patient from remaining infectious while on ineffective medication.
When is this test recommended?
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For every patient with a newly confirmed culture-positive TB diagnosis.
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To establish a baseline for treatment.
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If a patient had TB treatment in the past (relapse cases), to ensure the bacteria haven’t developed resistance.
Sample Requirements:
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Specimen: Positive Culture Isolate. (The lab first grows the bacteria from Sputum or Body Fluids, then performs this test on the growth).
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Container: Liquid Culture Tube (MGIT).
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Preparation: N/A (Performed on lab isolate).
