A study on fingerprint patterns of Mycobacterium tuberculosis and clinical application
Objective To establish a method of DNA fingerprint of Mycobacterium tuberculosis ( M.tb ) performed by restriction fragment length polymorphism (RFLP) and to study molecular epidemiology profile of M.tb clinical strains. Methods Chromosomal DNA of M.tb was transferred into a nylon filter and hybridized with 245bp of 6110 which labeled using random primer with digoxigenin-dUTP, alkali-labile and detection of hybrids by eneyzme immunoassay. Results 127 M.tb clinical strains detected were belong to 4 clusters according to the homology of IS6110 fingerprint. The character of every cluster: Dice was over 70% among the strains of cluster A and all the strains of cluster A contained these fragments of 1.3kb, 1.9kb, 2.1kb, 2.7kb, 3.3kb, 4.5kb , 5.0kb, 6.5kb and resembling the strains in Beijing; Dice among cluster B was also over 70% and resembling a cluster except being short of less than 1.9kb; Dice among cluster C was over 55% and shared these fragments of 1.3kb, 2.2kb, 3.3kb, 5.5kb; cluster D had a high degree of polymorphism and shared none fragment. Dice among the cluster A, B and C is over 55% and share some fragments, so we called them "clustered strains" and by contraries, cluster D, in which no fragment being shared was called "non-clustered strains". Rate of recent transmission was largely among the younger; A cluster was fewer among the resistant strains. Conclusion 39.7% clinical strains in Shenzhen was resembling with the strains in Beijing. The individuals essthan 30 years of age were recent transmission in Shenzhen and a few resistant strains belongs to cluster A.