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Free Content Evaluation of a commercial ligase chain reaction assay for the diagnosis of pulmonary and extra-pulmonary tuberculosis

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SETTING: Egas Moniz Hospital, Lisbon, Portugal.

OBJECTIVE: To evaluate the Ligase Chain Reaction (LCx®) Mycobacterium tuberculosis Assay for the direct detection of M. tuberculosis complex in respiratory specimens after smear observation, and its suitability for non-respiratory clinical specimens.

DESIGN: Analysis of 156 specimens collected from 123 patients with pulmonary tuberculosis and/or extra-pulmonary involvement.

RESULTS: Among 93 pulmonary secretions and 63 extra-pulmonary samples and after resolution of discrepancies based on clinical and laboratory findings, two pulmonary samples from a patient with a diagnosis of sarcoidosis, four samples of cerebrospinal and one of seminal fluid were considered as false positives. Two tissue biopsy samples, one pericardial effusion and one pulmonary secretion from patients strongly suspected of having tuberculosis were considered as false negatives for the assay, without inhibition of amplification. All specimens yielding M. avium on culture were LCx negative.

CONCLUSION: The LCx® Mycobacterium tuberculosis Assay was found to be useful for the rapid identification of M. tuberculosis complex in all types of specimens. It revealed a high specificity both in pulmonary and extra-pulmonary products, and a sensitivity of 97% for the pulmonary secretions and of 75% for the extra-pulmonary specimens, independently of the bacilloscopy results.
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Keywords: Ligase Chain Reaction Assay; direct detection; early diagnosis; pulmonary/extra-pulmonary tuberculosis

Document Type: Regular Paper

Affiliations: 1: Departamento de Microbiologia e Centro de Malaria e Outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal 2: Clinical Pathology Service, Hospital de Egas Moniz, Lisboa, Portugal

Publication date: June 1, 1999

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  • The International Journal of Tuberculosis and Lung Disease (IJTLD) is for clinical research and epidemiological studies on lung health, including articles on TB, TB-HIV and respiratory diseases such as COVID-19, asthma, COPD, child lung health and the hazards of tobacco and air pollution. Individuals and institutes can subscribe to the IJTLD online or in print – simply email us at [email protected] for details.

    The IJTLD is dedicated to understanding lung disease and to the dissemination of knowledge leading to better lung health. To allow us to share scientific research as rapidly as possible, the IJTLD is fast-tracking the publication of certain articles as preprints prior to their publication. Read fast-track articles.

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