What is the difference between Multidrug Resistance (MDR), Extensively Drug-Resistant (XDR), and Pan-Drug Resistant (PDR)?

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Last updated: April 3, 2025View editorial policy

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From the Research

Multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) are critical healthcare challenges that require prompt diagnosis and treatment with newer drugs and regimens, such as bedaquiline and delamanid, to improve outcomes and prevent the spread of resistance. The management of MDR-TB and XDR-TB is complex and requires a combination of multiple antibiotics, often including last-resort agents, and should be guided by susceptibility testing whenever possible, with consultation from infectious disease specialists 1. The development of these resistant organisms is primarily driven by antibiotic overuse and misuse, highlighting the importance of appropriate prescribing practices to preserve our remaining effective antimicrobials.

Key Considerations

  • MDR-TB is defined as resistance to at least isoniazid and rifampicin, while XDR-TB is defined as MDR-TB with additional resistance to any fluoroquinolone and at least one second-line injectable drug 2.
  • The rate of bedaquiline resistance in MDR-TB cases was 7.69%, while it was observed to be 10.75% in cases of pre-XDR-TB, and significantly higher at 37.04% in cases of XDR-TB 1.
  • Newer drugs, such as bedaquiline and delamanid, have shown excellent in vitro activity against MDR-TB isolates, but the emergence of resistance is a concern 3.
  • Prevention strategies, including antimicrobial stewardship programs, strict infection control measures, patient isolation, and enhanced surveillance, are crucial to prevent the spread of resistance 4.

Treatment Approaches

  • Treatment of MDR-TB and XDR-TB should be individualized and based on susceptibility testing, with the use of newer drugs and regimens, such as bedaquiline and delamanid, to improve outcomes 5.
  • Combination therapy with multiple antibiotics, often including last-resort agents, is typically required to manage MDR-TB and XDR-TB.
  • Consultation with infectious disease specialists is recommended to guide treatment decisions.

Prevention and Control

  • Antimicrobial stewardship programs, strict infection control measures, patient isolation, and enhanced surveillance are crucial to prevent the spread of resistance 4.
  • Appropriate prescribing practices, including the use of antibiotics only when necessary and for the shortest duration possible, are essential to preserve our remaining effective antimicrobials.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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