[Fingerprinting of mycobacterial DNA in the molecular epidemiology of tuberculosis]

A group of 24 strains of Mycobacterium tuberculosis was analyzed in a pilot study using the RFLP technique based on detection of IS6110 in chromosomal DNA predigested with PvuII. All strains had 5-15 copies of IS6110 and the method was also used in subsequent studies: From a total number of 15 strains obtained from patients from six families and institutions resp. according to the identity of finger prints transmission of TB infection was proved in 11 instances and ruled out in the remaining four because of a different RFLP profile of the finger prints. In the investigation of prevalence of different types of RFLP 75 strains of M. tuberculosis isolated consecutively during a four-month period in 1995 from patients living in Prague were analyzed. In the group a sub-group of 22 strains in seven clusters was differentiated which were formed by two to six strains with identical or related RFLP profiles and a group of 53 non-clustered strains with individually different RFLP patterns. The authors conclude from the assembled results that the great majority of findings corresponding to a 29% ratio of clustered strains is formed by endogenous reactivation from persistent tuberculous foci and the remaining part of 71% non-clustered strains is ascribed to recent exogenous superinfection.