Rapid detection of Mycobacterium tuberculosis in respiratory specimens, blood and other non-respiratory specimens by amplification of rRNA
Abstract:SETTING: Diagnostic methods employing gene technology based on amplification of DNA or RNA are expected to improve the speed, sensitivity, and specificity of Mycobacterium tuberculosis detection. The Amplified Mycobacterium Tuberculosis Direct Test (AMTDT) enables the amplification and detection of M. tuberculosis rRNA directly from respiratory specimens.
OBJECTIVE: To evaluate the performance of the AMTDT in direct detection of M. tuberculosis in respiratory specimens, blood and other clinical samples, and to compare this method with conventional culture and staining techniques.
DESIGN: A total of 554 samples from 450 patients were examined in this study. All clinical specimens (with the exception of bone marrow aspirates and blood samples) were digested and decontaminated with sodium dodecyl (lauryl) sulfate (SDS)-NaOH. Bone marrow aspirates and blood samples were treated with 10% SDS. All processed samples were stained by auramine-rhodamine fluorochrome and inoculated onto Löwenstein-Jensen and Coletsos solid media, and into BACTEC-12B medium. In addition, the blood samples were inoculated into BACTEC 13A medium. The AMTDT was performed according to manufacturer's instructions. In those cases where discrepant results were obtained for AMTDT and cultures, patients' clinical data and other microbiological results were evaluated.
RESULTS: The sensitivity, specificity, and positive and negative values for AMTDT were 87.5, 100, 100, and 96.7%, respectively, in respiratory specimens and 86.8, 100, 100, and 92.8%, respectively, in non-respiratory specimens. The differences in sensitivity of these two groups of specimens were not highly statistically significant (P > 0.005).
CONCLUSION: The sensitivity and specificity of the AMTDT were satisfactory for detection of M. tuberculosis in all types of clinical samples. Some minor changes in assay format and laboratory protocols may increase the sensitivity of the AMTDT without adversely affecting its specificity.
Document Type: Regular Paper
Affiliations: 1: Servicio de Microbiología, Hospital Universitario Germans Trias i Pujol, Barcelona, Spain; and Departamento de Genética y Microbiología, Facultad de Medicina, Universidad Autónoma de Barcelona, Barcelona, Spain 2: Servicio de Microbiología, Hospital Universitario Germans Trias i Pujol, Barcelona, Spain 3: Servicios de Neumología, Hospital Universitario Germans Trias i Pujol, Barcelona, Spain 4: Servicios de Pediatría, Hospital Universitario Germans Trias i Pujol, Barcelona, Spain
Publication date: 1997-12-01
The International Journal of Tuberculosis and Lung Disease publishes articles on all aspects of lung health, including public health-related issues such as training programmes, cost-benefit analysis, legislation, epidemiology, intervention studies and health systems research. The IJTLD is dedicated to the continuing education of physicians and health personnel and the dissemination of information on tuberculosis and lung health world-wide.
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