Nonconventional and new methods in the diagnosis of tuberculosis: feasibility and applicability in the field

Abstract

Tuberculosis (TB) remains one of the major causes of death from a single infectious agent worldwide. Of great concern for TB control is the emergence of drug resistance. Since there is no cure for some multidrug-resistant strains of Mycobacterium tuberculosis, there is concern that they may spread around the world, stressing the need for additional control measures, such as new diagnostics, better drugs for treatment, and a more effective vaccine.Pulmonary TB can be diagnosed by its symptoms, chest radiography, sputum smear microscopy and by cultivation of M. tuberculosis, which is considered as the gold standard. Recent advances in molecular biology and molecular epidemiology, and a better understanding of the molecular basis of drug resistance in TB, have provided new tools for rapid diagnosis; however, the high cost of most of these techniques, and their requirement for sophisticated equipment and skilled personnel have precluded their implementation on a routine basis, especially in low-income countries.Other nonconventional diagnostic approaches proposed include the search for biochemical markers, detection of immunological response and early detection of M. tuberculosis by methods other than colony counting.In the present article, some of these approaches will be reviewed and the feasibility for their implementation in diagnostic laboratories will be discussed.

Rapid detection and differentiation of mycobacterial species using a multiplex PCR system

“…Advances in molecular biology techniques and the information provided by sequencing the complete genome of M. tuberculosis prompted the development of new tools for the rapid diagnosis of tuberculosis, including the differentiation of M. tuberculosis from other mycobacteria 33,34 . Multiplex PCR has the ability to amplify different targets simultaneously and has been used to detect and identify mycobacteria from the Mycobacterium tuberculosis complex and nontuberculous mycobacteria 26,27,35,36 .…”

Comparison of recoveries of Mycobacterium tuberculosis using the Automated BACTEC MGIT 960 System and Lowenstein-Jensen Medium in clinically suspected cases of tubercular meningitis in children

“…[5] Immunological and serological assays have not stood the test of confidence to warrant their use in conventional diagnostics. [6] In the face of such limitations, the need of the hour is for less complicated and more accurate diagnostic tests. Liquid culture media such as that used in the Mycobacterial Growth Indicator Tube (MGIT) (Becton Dickinson) system have been introduced over the years and been extensively evaluated.…”

A Retrospective Analysis on the Use of Algorithm for the Diagnosis of Mycobacterium Tuberculosis

“…It can detect 100 bacilli.mL-1 of sputum in comparison with 5,000-10,000 bacilli.mL-1 needed for microscopy. Following decontamination and liquefaction procedures, sputum samples are inoculated and incubated for morphological growth, which usually occurs after several weeks of incubation (12). As proposed by the algorithm, the samples can be evaluated using a sequential order of EZN, culture, and, if suitable laboratory conditions are available, PCR.…”