Drug-resistant tuberculosis

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(Redirected from MDR-TB)

Background

Classification

  • Multidrug resistant tuberculosis (MDR-TB): resistance to isoniazid and rifampicin
    • Rifampin monoresistance is quite rare, so MDR is usually inferred from rifampin resistance alone
  • Extensively drug-resistant tuberculosis (XDR-TB): resistance to at least isoniazid and rifampicin, and to any fluoroquinolone, and to any of the three second-line injectables
  • Totally drug-resistant tuberculosis (TDR-TB): not well-defined

Resistance Mechanisms

  • 90% of isoniazid resistance is from known mutations in either the katG or InhA genes
  • 95% of rifampin resistance is from known mutations in the rpoB gene

Risk Factors

  • The strongest predictor of MDR-TB is prior TB treatment (increases from 3% to 18% of cases)
  • Residence in country with higher rate of MDR-TB: India (8%/13% new/previous treatment), Philippines (12%/15%), China (7%/8%), Viet Nam (14%/10%), Pakistan (8%/7%), Ethiopia (6%/13%), Somalia (6%/8%), Haiti (unclear), Hong Kong (5%/7%), Afghanistan (unclear)
  • Exposure to person with MDR-TB
  • HIV infection
  • Other risk factors include younger age and more recent arrival from endemic country

Management

BPaLM

Specific Resistance Patterns

Resistance To Replace With Regimen Total Duration
INH FQN 6 months RMP+EMB+PZA+FQN 6 months from date FQN started
INH FQN 2 months RMP+EMB+PZA+FQN then 4 months RMP+EMB+FQN 6 months from date FQN started
RMP FQN 2 months daily INH+EMB+PZA+FQN then 10-16 months INH+EMB+FQN 18 months from date FQN started
RMP None 2 months INH+EMB+PZA, then 16 months INH+EMB 18 months from date FQN started
EMB None 2 months INH+RMP+PZA, then 4 months INH+RMP 6 months from start of therapy
PZA None 2 months INH+RMP+EMB, then 7 months INH+RMP 9 months from start of therapy
INH+EMB FQN 6 months daily RMP+PZA+FQN 6 months from date FQN started
INH+PZA FQN 9 months RMP+EMB+FQN 9 months from date FQN started
INH+EMB+PZA FQN+injectable 2 months TMP+FQN+injectable, then 7 months RMP+FQN 9 months from date FQN started
  1. Nyang'wa BT, Berry C, Kazounis E, Motta I, Parpieva N, Tigay Z, Solodovnikova V, Liverko I, Moodliar R, Dodd M, Ngubane N, Rassool M, McHugh TD, Spigelman M, Moore DAJ, Ritmeijer K, du Cros P, Fielding K; TB-PRACTECAL Study Collaborators. A 24-Week, All-Oral Regimen for Rifampin-Resistant Tuberculosis. N Engl J Med. 2022 Dec 22;387(25):2331-2343. doi: 10.1056/NEJMoa2117166. PMID: 36546625.