This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Galí, N. Search for Related Content PubMed PubMed Citation Articles by Galí, N.

 Previous Article  |  Next Article 

Journal of Clinical Microbiology, January 2006, p. 201-205, Vol. 44, No. 1
0095-1137/06/$08.00+0     doi:10.1128/JCM.44.1.201-205.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Use of a Mycobacteriophage-Based Assay for Rapid Assessment of Susceptibilities of Mycobacterium tuberculosis Isolates to Isoniazid and Influence of Resistance Level on Assay Performance

Servei de Microbiologia, Hospital Universitari Germans Trias i Pujol,¹ Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona,² Hospital Universitari de Bellvitge, and Servei de Microbiologia,³ Hospital de la Santa Creu i Sant Pau, Barcelona, Spain⁴

Received 26 June 2005/ Returned for modification 17 August 2005/ Accepted 21 October 2005

We standardized and assessed the performance of an in-house microtiter assay for determining the susceptibilities of Mycobacterium tuberculosis clinical isolates to isoniazid based on mycobacteriophage amplification technology. Seventy isolates (43 resistant and 27 sensitive according to the BACTEC 460 radiometric method and MIC determination) were studied. The isoniazid resistance molecular mechanism was previously determined by sequencing the entire katG gene and the mabA-inhA regulatory region. The sensitivity of the mycobacteriophage-based assay in detecting isoniazid resistance was 86.1%, the specificity achieved was 92.6%, and the overall accuracy was 88.6%. In order to assess the possible influence of resistance levels on the mycobacteriophage-based-assay sensitivity, the results were analyzed according to the isoniazid MICs. All the isolates exhibiting high-level resistance (MIC 2 µg/ml) were scored as resistant by the mycobacteriophage-based assay (100% concordance), and 95% showed mutations or deletions in the catalytic domain of the katG gene. In contrast, 26.1% of the low-level-resistance strains (MICs, 0.25 to 1 µg/ml) were misclassified, and 66.7% had alterations in the mabA-inhA regulatory region. The mycobacteriophage-based assay could be used as a rapid method to detect the isoniazid susceptibility pattern, although data from those areas with high rates of low-level-resistance strains should be interpreted with caution. The features of the assay make it suitable for widespread application due to its low technical demand and cost.

This article has been cited by other articles:

• Chauca, J. A., Palomino, J.-C., Guerra, H. (2007). Evaluation of rifampicin and isoniazid susceptibility testing of Mycobacterium tuberculosis by a mycobacteriophage D29-based assay. J Med Microbiol 56: 360-364 [Abstract] [Full Text]  
• Brossier, F., Veziris, N., Truffot-Pernot, C., Jarlier, V., Sougakoff, W. (2006). Performance of the Genotype MTBDR Line Probe Assay for Detection of Resistance to Rifampin and Isoniazid in Strains of Mycobacterium tuberculosis with Low- and High-Level Resistance.. J. Clin. Microbiol. 44: 3659-3664 [Abstract] [Full Text]