Rapid identification and susceptibility testing of Mycobacterium tuberculosis from MGIT cultures with luciferase reporter mycobacteriophages

J Med Microbiol. 2003 Jul;52(Pt 7):557-561. doi: 10.1099/jmm.0.05149-0.

Abstract

In a prospective study conducted in a diagnostic laboratory in Mexico City, luciferase reporter mycobacteriophages (LRPs) were evaluated for their utility and performance in identification and antibiotic-susceptibility testing of Mycobacterium tuberculosis complex (MTC) isolates from MGIT-960 cultures. Eighty-four consecutive MGIT cultures recovered from 54 patients were included in this study. The LRPs confirmed mycobacterial growth in 79 (94 %) of 84 MGIT cultures. Failure to confirm growth was due to low inoculum (n = 1) or growth with non-tuberculous mycobacteria (n = 4). The median time to confirmation of MGIT cultures was 1 day (range 1-55). Confirmed cultures were identified with p-nitro-alpha-acetylamino-beta-hydroxypropiophenone (NAP), a selective inhibitor of MTC species, and results obtained with LRPs were compared with those obtained by BACTEC-460. The sensitivity and specificity of the LRP NAP test were respectively 97 and 100 %, and the median turnaround time for identification was 3 days with both methods. The accuracy and speed of the LRPs for susceptibility testing with rifampicin, streptomycin, isoniazid and ethambutol were compared with BACTEC-460 and discrepant results were tested by the conventional agar proportion method. In total, 72 MTC cultures were tested. The overall agreement between the LRPs and BACTEC-460 was 98.6 %. Four isolates (5.6 %) were falsely identified as ethambutol-resistant. The median turnaround time for susceptibility testing was 3 days (range 3-57) with the LRPs and 9 days (range 7-29) with BACTEC-460. LRPs offer an accurate and rapid approach for identification and susceptibility testing of M. tuberculosis from MGIT-960 cultures.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antitubercular Agents / pharmacology*
  • Drug Resistance, Multiple, Bacterial*
  • Genes, Reporter*
  • Humans
  • Luciferases / genetics*
  • Microbial Sensitivity Tests / methods*
  • Mycobacteriophages / genetics*
  • Mycobacterium tuberculosis / drug effects*
  • Mycobacterium tuberculosis / physiology
  • Mycobacterium tuberculosis / virology*
  • Tuberculosis / microbiology

Substances

  • Antitubercular Agents
  • Luciferases