Advances in Clinical Diagnosis of Tuberculosis: Past, Present, and Future

Introduction

Tuberculosis (TB) disease is a global public health malady, claiming almost 1.5 million lives annually . Putting India on a global scenario, it is found that one-fifth of the global incidence of TB occurs in India (Central TB division 2010). Tuberculosis is caused by members of the Mycobacterium tuberculosis (Fig. 1) complex [MTBC], which includes M. tuberculosis, M. bovis, M. africanum, M. canetti, and M. microti. TB is a major concern in industrialized countries due to their socio-economic factors such as immigration, a rapid increase in poverty, malnutrition, war, and limited medication access. To address this grave disease, the most important aspects are its effective treatment, and its proper diagnosis. The management of TB includes a 4-drug regime, and the treatment period is about six months long. To reduce transmission of this disease, and to achieve disease elimination, early, and accurate diagnosis followed by proper treatment is vital. However, there are still a lot of challenges associated with the diagnosis of TB with specificity, and sensitivity.

Figure 1.

Structure of Mycobacterium

2. Diagnosis Of Tb From Direct Specimens

For the most effective treatment of TB, an early diagnosis becomes a pre-requisite. In patients with active TB, the infection of M. tuberculosis is high in the samples which can be directly analyzed for its presence. Any diagnostic method which can give the result on the same day and make a diagnosis at the point where patient consultation and presentation occurs is said to be a point-of-care (POC) diagnosis (Gondil and Chhibber 2018, Doctor, Mehra et al. 2019). The WHO, and Stop TB Partnership are emphasizing on developing a POC for the diagnosis of TB. So far, there are certain diagnostic methods available that can be translated as POC diagnosis of TB and they are represented in Figure 1.

Figure 2.

Schematic representation showing varied POC diagnostic methods for TB detection