[Use of IS6110 polymorphism analysis in molecular epidemiological studies of tuberculosis (Belgrade study results)]

Tuberculosis (TB) remains a major health problem worldwide. One of the main approaches to tackling TB today is the control of transmission of the disease through monitoring the transmission of specific strains of Mycobacterium tuberculosis. In the past, efforts to type strains of M. tuberculosis were hampered by the lack of strain-specific phenotypic markers. In recent years, novel approaches to studying the epidemiology of TB have been provided by molecular biological techniques based on DNA fingerprinting. The most widely used polymorphic marker is the transposable element IS6110, which is an insertion sequence found throughout M. tuberculosis complex. It is a highly polymorphic marker which varies in both copy number and location in the M. tuberculosis genome. A standardized methodology for IS6110 DNA fingerpriniting of M. tuberculosis exploits restriction fragment length polymorphism analysis. To date, IS6110 fingerprinting has been successfully used to trace the TB transmission in different regions and populations, to quantify the relative contribution of recent infection to the TB population burden, to answer the question of endogenous reactivation versus exogenous reinfection, to trace small-scale outbreaks of TB, to analyze spread of drug-resistant and multidrug resistant strains, to confirm laboratory cross-contaminations, etc. The objective of this study was to illustrate the basic principles of molecular epidemilological studies of TB. Results of the study, which provided the first insight into the status of TB in Belgrade based on implementation of molecular methods, were used as an example.