Direct detection of Mycobacterium tuberculosis complex in respiratory specimens by Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test and Roche Amplicor Mycobacterium Tuberculosis Test

Abstract

Two hundred and fifty-six sputum, bronchoalveolar lavage, and bronchial and tracheal aspirate specimens from 243 patients were tested for the presence of Mycobacterium tuberculosis complex by auramine fluorochrome staining, rRNA target amplification (Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test [AMTD]), and PCR (Roche Amplicor Mycobacterium Tuberculosis Test [Amplicor PCR]). The results were compared with those of conventional Löwenstein-Jensen tube culture and BACTEC radiometric liquid culture. A total of 26 specimens from 18 patients were culture positive for M. tuberculosis. In addition, seven specimens were positive by staining and by culture for other Mycobacterium species but negative by nucleic acid amplification methods and were not included in the comparison. When compared with that for culture, the sensitivities of the techniques were as follows: for staining, 80.8%; for Gen-Probe AMTD, 84.6%; and for Roche Amplicor PCR, 84.6%. The specificities were 99.1, 98.7, and 99.1%, respectively. After resolution of discrepant results by review of the patients' clinical data, 29 specimens from 21 patients were considered positive, and the overall sensitivities, specificities, and positive and negative predictive values were 89.7, 100, 100, and 98.7% for culture; 75.9, 99.5, 95.7, and 96.9% for staining; 86.2, 100, 100, and 98.2% for Gen-Probe AMTD; and 82.8, 100, 100, and 97.9% for Roche Amplicor PCR, respectively. It is concluded that both nucleic acid amplification methods are rapid, sensitive, and specific methods for the detection of M. tuberculosis in respiratory specimens.

Evaluation of the semiautomated Abbott LCx Mycobacterium tuberculosis assay for direct detection of Mycobacterium tuberculosis in respiratory specimens

“…The results were confirmed and were considered false negative, although two specimens showed a signal 20 times greater than that of the negative VOL. 35,1997 RAPID DETECTION OF M. TUBERCULOSIS BY LCR 1997 on July 10, 2020 by guest http://jcm.asm.org/ control (S/CO, 0.77 in both cases). These 18 specimens were from 14 patients, including 2 patients with multidrug-resistant TB.…”

“…Vuorinen et al (35) evaluated the Gen-Probe Amplified M. tuberculosis Direct Test (AMTDT) and Amplicor M. tuberculosis test (Roche Diagnostic Systems, Somerville, N.J.) with 256 respiratory specimens from 243 patients, with a positivity rate of 12.7% and a staining sensitivity of 76%. The sensitivities, specificities, PPVs, and NPVs were 86.2, 100, 100, and 98.2%, respectively, for AMTDT and 82.8, 100, 100, and 97.8%, respectively, for the Amplicor test.…”

Comparison of two different PCR detection methods. Application to the diagnosis of pulmonary tuberculosis

“…In a study of 5000 specimens, there was a sensitivity of 83.5% and a specificity of 99% (6), and Carpentier et al reported 86% sensitivity and 98% specificity (5). The use of commercial techniques that increase standardization has led to comparable results from several different laboratories (16,18,28). For example, the results of one multicenter study, in which one of these techniques was evaluated in six different laboratories, show a sensitivity of 91.4% for samples with positive staining and 60.9%) for those with negative staining, with a specificity Reamplification techniques produce an increase in sensitivity and have been used to diagnose extrapulmonary tuberculosis (26), but they increase the possibility of cross-reactions since each PCR tube may contain up to 10l2 copies of an amplicon, and the smallest aerosolized drop may contain as many as lo5 copies of that amplicon.…”

Automatized PCR evaluation ofMycobacterium tuberculosiscomplex in respiratory and nonrespiratory specimens

“…The first two commercial tests used for the identification of Mycobacterium tuberculosis were the Amplicor Mycobacterium tuberculosis test (MTB; Roche Diagnostic Systems, Rotkreuz, Switzerland) and the Mycobacterium tuberculosis direct test (MTDT; Gen-Probe, Inc., San Diego, CA, USA). The average sensitivity and specificity of these assays were 70%-95% in clinical studies (Vuorinen et al, 1995;Dalovisio et al, 1996;Ichiyama et al, 1996). In a multicenter study, Noordhoek et al (1996) reported that results obtained with both methods were not reproducible, and mycobacterial detection from clinical specimens therefore required the development of reliable, standardized and automatized new methods were required.…”