THE IMPACT OF NEW TECHNOLOGY ON THE LABORATORY'S CONTRIBUTION TO THE DIAGNOSIS AND MANAGEMENT OF MYCOBACTERIAL DISEASE

Abstract

From the time of the discovery of the tubercle bacillus in the late nineteenth century until the introduction of chemotherapy in the mid-twentieth, the role of the laboratory in the management of tuberculosis was limited because the treatment of the disease was nonspecific. The advent of specific chemotherapy and the recognition of human diseases caused by a number of mycobacterial species other than M. tuberculosis increased the scope and importance of the clinical laboratory in guiding the diagnosis and management of mycobacterial disease. This included the isolation of mycobacteria, the identification of the isolates, the determination of their susceptibilities to chemotherapeutic agents and their subtyping for epidemiologic purposes. In spite of the enhanced role it has played in the past forty years, the laboratory's contribution has been impeded by the slow growth of mycobacteria, which causes delays of weeks or months between submission of a specimen and the availability of a definitive report. In the meantime both the urgency and the complexity of diagnosis and management of mycobacterial disease have increased with the emergence of epidemics of these diseases associated with the acquired immunodeficiency syndrome (AIDS). This development has also increased the need for recognition of tubercle bacilli in such specimens as blood and stools, which were only infrequently studied in past years.
Recent developments in microchemical and immunologic technology, and especially molecular biology, are greatly reducing the time needed to get information that contributes to diagnosis and management of mycobacterial disease. These include solid phase immunologic assays, sequencing of selected nucleic acid regions and development of specific probes, and exquisitely sensitive isotopic or enzymatic amplification techniques for the detection of traces of products.