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Updated: Sep 25, 2026
A High-throughput Compatible Assay to Evaluate Drug Efficacy against Macrophage Passaged Mycobacterium tuberculosis
Published on: March 24, 2017
Rapid identification and susceptibility testing of Mycobacterium tuberculosis from MGIT cultures with luciferase
Niaz Banaiee1, Miriam Bobadilla-Del-Valle1, Paul F Riska1
1Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA, USA 2Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubiran, Mexico City, Mexico 3State University of New York - Downstate Medical Center, Brooklyn, NY, USA 4Howard Hughes Medical Institute, Albert Einstein College of Medicine, Bronx, NY, USA 5Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
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.
