The impact of repeated NALC/NaOH- decontamination on the performance of Xpert MTB/RIF assay

Tuberculosis (Edinb). 2018 May:110:56-58. doi: 10.1016/j.tube.2018.04.001. Epub 2018 Apr 5.

Abstract

The Xpert MTB/RIF assay detects Mycobacterium tuberculosis in unprocessed or NALC/NaOH- decontaminated sputum. The effect of repeated NALC/NaOH-decontamination on several Xpert performance parameters was assessed in this study. A second NALC/NaOH-decontamination had no effect on the binary Xpert-outcome but increased the value for the quantitative readout (CTmin). Repeated decontamination was not associated with PCR-inhibition or invalid results. The CTmin of M.tb positive samples was higher in inhibited Xpert runs. Our data indicate that NALC/NaOH-decontamination has an effect on the performance of the Xpert assay, and that CTmin readouts of decontaminated sputum samples should be interpreted with caution.

Trial registration: ClinicalTrials.gov NCT00864383.

Keywords: Quantitative PCR; Sputum processing; Xpert-inhibition; Xpert-performance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcysteine* / chemistry
  • Bacteriological Techniques / methods
  • Decontamination* / methods
  • Humans
  • Mycobacterium tuberculosis* / isolation & purification
  • Polymerase Chain Reaction / methods
  • Sodium Hydroxide* / chemistry
  • Specimen Handling* / methods
  • Sputum / microbiology
  • Tuberculosis / diagnosis

Substances

  • Acetylcysteine
  • Sodium Hydroxide

Associated data

  • ClinicalTrials.gov/NCT00864383