The Changing Landscape of Diagnostic Services for Tuberculosis

Abstract

During the last decade there has been a dramatic change in the laboratory approach to tuberculosis (TB) diagnosis in the developing world. This change began with the realization that acid-fast bacillus smear microscopy alone was totally inadequate to deal with the dual problems of human immunodeficiency virus (HIV)-associated TB and drug-resistant TB that threaten to undermine global progress in TB control. Subsequently, increased financial resources for TB laboratory services and the establishment of a systematic process for endorsement of new TB diagnostic tools and approaches by the World Health Organization (WHO) have led to rapid expansion of TB laboratory services and the availability of several new diagnostic tests that have been introduced. These include both commercial automated and noncommercial systems for phenotypic mycobacterial liquid culture and drug susceptibility testing, a simple and inexpensive test for mycobacterial species identification in culture isolates, light-emitting diode fluorescence microscopy, and rapid molecular methods for TB case detection and the diagnosis of drug-resistant TB. The latter methodologies that include line probe assays and an automated cartridge-based real-time polymerase chain reaction (PCR)-based test are being scaled up at an unprecedented pace and are truly revolutionizing the diagnosis of drug-resistant TB. On the other hand, little progress has been made in the quest for a true point-of-care test for TB. Fortunately, this is being addressed in several discovery initiatives that hopefully will provide impetus for the development of rapid, accurate TB diagnostics for the lowest level of the health system.

MTB-DR-RIF 9G test: Detection and discrimination of tuberculosis and multi-drug resistant tuberculosis strains

“…Moreover, for accurate drug therapy it is important to detect mutations so that physicians can choose a potent drug against the particular MTB-DR strain [10,11]. Therefore, a diagnostic tool which is rapid, accurate, highly sensitive, and field-deployable, is essential for the timely detection of the drug resistant strains and selection of drugs for the treatment [12].…”

Molecular Characterisation of HIV Associated Tuberculosis Compared to Conventional Methods

“…This change began with the realization that acid-fast bacillus smear microscopy alone was totally inadequate to deal with the problems of HIV associated TB and drugresistant TB. [1] Direct smear examination with Ziehl-Neelsen (ZN) staining for the diagnosis of TB as employed but its low sensitivity is a major drawback. Major advances in molecular techniques, which rapidly identify Mycobacterium (deoxyribonucleic acid) DNA in sputa, may overcome these obstacles.…”

MUBII-TB-DB: a database of mutations associated with antibiotic resistance in Mycobacterium tuberculosis

“…The limitation of the TB expansion is thus based on the improvement and generalization of diagnostic methods [5] and early antibiotic therapy. The WHO recommends the following combined therapy employing first-line antibiotics: rifampicin (or rifabutin), isoniazid, pyrazinamide and ethambutol for two months followed by rifampicin and isoniazid for four months [6].…”