Introduction:
Epidemiological studies of tuberculosis cover a number of medical disciplines, such as clinical medicine, pathology, microbiology, medical statistics, as well as biochemistry and genetics. The rapid development of modern techniques in molecular biology observed in recent years has also allowed their use in the studies of the epidemiology of tuberculosis. These techniques are based on the detection in the mycobacterial genome of characteristic sequences, their organization and polymorphism, and also the identification of genes which determine virulence factors and antibiotic resistance.

Objective:
Characteristics of the main genotyping methods applied in molecular epidemiological investigations of tuberculosis.

Brief description of the state of knowledge:
Genome sequencing allows the determination of molecular patterns (fingerprinting) of Mycobacterium tuberculosis strains analyzed and their discrimination. This is crucial when defining the findings of epidemiological investigations and, above all, recognizing the source of tuberculosis and routes of its transmission. Before molecular methods for epidemiological investigations had been developed, most of the research was limited to discriminating on the basis of biochemical and serological features, phage typing and drug resistance phenotype. With the advent of molecular techniques, epidemiologists began using effective markers to track the transmission and to identify the phylogenetic characteristics of M. tuberculosis strains.

Summary:
The most important criteria for selection of the method of typing are: the nature of the sample, its size, and the time at which the material was collected. The methods currently used are characterized by varied discriminatory power, the value of which is determined by the degree of clustering/grouping of strains into potential epidemiological groups within which the transmission occurred.