Tuberculosis Today: Microbial Insights, Epidemiological Trends, and the Role of Molecular Diagnostics

Abstract

Tuberculosis (TB), caused by Mycobacterium tuberculosis, remains a global health problem. One of the characteristic features of mycobacteria is their exceptional resistance to environmental factors and their slow growth rate, both of which significantly prolong microbiological diagnostics. Due to the mortality rate and the rising prevalence of multidrug-resistant (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB), early detection and prompt initiation of treatment are extremely important. Traditional diagnostic methods, such as microscopic examination and culture on solid and liquid media, are still important, but are time-consuming and resource-intensive. However, the dynamic development of nucleic acid amplification techniques (NAATs), genotyping assays, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has accelerated the identification of mycobacteria and the detection of drug resistance. Early and precise diagnosis is essential for effective disease control and improved treatment outcomes. This paper reviews the current state of knowledge on tuberculosis; including biological and structural characteristics of mycobacteria; the epidemiology of the disease; and the role of the main diagnostic methods; with a particular focus on molecular methods and MALDI-TOF MS. This paper highlights their advantages and limitations and discusses their implications for the future of TB diagnosis and control.

Keywords: MALDI-TOF MS; NAATs; genotyping assays; molecular diagnostics; tuberculosis.

Figure 1

Flowchart of conventional, molecular, and mass spectrometry-based methods used for the identification and diagnosis of tuberculosis. The tests used for identification and diagnosis of tuberculosis are divided into three subgroups (marked in blue, orange, and green). Tests in the blue box—Xpert MTB/RIF assay (Cepheid, Sunnyvale, CA, USA), BD MAX MDR-TB (Becton Dickinson, Sparks, MD, USA), FluoroType MTBDR (Hain Lifescience GmbH, Nehren, Germany) are performed directly from clinical material after its processing (blue arrow). The test in the orange box—(MTB/MDR test (Xiamen Zeesan Biotech Co., Ltd., Xiamen, China) is performed directly from clinical material after processing or from liquid or solid culture (orange arrows). Tests in the green box—(GenoType MTBC (Hain Lifescience GmbH, Nehren, Germany), MALDI-TOF MS (Bruker Daltonics, Bremen, Germany) are performed from liquid or solid cultures (green arrows).

Figure 2

Representative result pattern of the GenoType MTBC assay. The strip shows hybridization bands for specific probes. CC (conjugate control) confirms successful conjugate binding, UC (universal control) verifies the amplification process, and MTBC control indicates the presence of MTBC DNA. The combination of band patterns allows precise differentiation of MTBC species and ensures assay reliability.