Current typing methods for Mycobacterium tuberculosis complex evolved from simple phenotypic
approaches like phage typing and drug susceptibility profiling to DNA-based strain typing methods, such
as IS6110-restriction fragment length polymorphisms (RFLP) and variable number of tandem repeats
(VNTR) typing. Examples of the usefulness of molecular typing are source case finding and epidemiological
linkage of tuberculosis (TB) cases, international transmission of MDR/XDR-TB, the discrimination
between endogenous reactivation and exogenous re-infection as a cause of relapses after curative treatment
of tuberculosis, the evidence of multiple M. tuberculosis infections, and the disclosure of laboratory
cross-contaminations.