PDR-TB, or Polydrug-resistant Tuberculosis, is tuberculosis caused by bacteria that are resistant to more than one anti-TB drug, excluding the combination of isoniazid and rifampin. In contrast, Multi-drug resistant TB (MDR-TB) specifically requires resistance to at least isoniazid and rifampin.
In essence, PDR-TB represents a level of drug resistance that falls between drug-susceptible TB and MDR-TB. It's crucial to identify and treat PDR-TB effectively to prevent further development of drug resistance, potentially leading to MDR-TB or extensively drug-resistant TB (XDR-TB).
Here's a breakdown to illustrate the difference:
| Category | Resistance Definition |
|---|---|
| Drug-Susceptible TB | Bacteria are susceptible to standard anti-TB drugs. |
| Polydrug-Resistant TB (PDR-TB) | Bacteria are resistant to more than one anti-TB drug, but not both isoniazid and rifampin. |
| Multi-drug Resistant TB (MDR-TB) | Bacteria are resistant to at least isoniazid and rifampin. |
| Extensively Drug-Resistant TB (XDR-TB) | Bacteria are resistant to isoniazid, rifampin, any fluoroquinolone, and at least one of the injectable second-line drugs (amikacin, kanamycin, or capreomycin). |
The significance of PDR-TB lies in its potential to evolve into more resistant forms of the disease. Proper diagnosis and treatment with appropriate second-line drugs are critical for managing PDR-TB cases and preventing further spread of resistance.
