The complexities of Xpert® MTB/RIF interpretation

Int J Tuberc Lung Dis. 2015 Mar;19(3):273-5. doi: 10.5588/ijtld.14.0432.

Abstract

The Xpert(®) MTB/RIF assay has demonstrated robust capability for diagnosing tuberculosis (TB) and rifampin (RMP) resistance. Optimal use of Xpert in diverse settings will require knowledge of challenges when interpreting the results. We present three selected cases from the United States, a low-burden TB setting, to highlight important clinical scenarios encountered with Xpert testing: rapid RMP resistance detection in a patient with pre-extensively drug-resistant TB who immigrated from the Philippines, false-positive RMP resistance detection, and Mycobacterium tuberculosis detection in a culture-negative patient. These cases demonstrate that a low pre-test probability of TB or drug-resistant TB can complicate the interpretation of the Xpert assay.

Publication types

  • Case Reports
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Aged
  • Antibiotics, Antitubercular / therapeutic use
  • Drug Resistance, Multiple, Bacterial
  • Female
  • HIV Seronegativity
  • Humans
  • Male
  • Middle Aged
  • Molecular Diagnostic Techniques / methods*
  • Molecular Diagnostic Techniques / standards
  • Mycobacterium tuberculosis / drug effects
  • Mycobacterium tuberculosis / isolation & purification
  • Nucleic Acid Amplification Techniques / methods*
  • Nucleic Acid Amplification Techniques / standards
  • Rifampin / therapeutic use
  • Specimen Handling
  • Sputum / microbiology
  • Treatment Outcome
  • Tuberculin Test
  • Tuberculosis, Multidrug-Resistant / drug therapy
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / drug therapy*
  • United States

Substances

  • Antibiotics, Antitubercular
  • Rifampin