Epidemiological evidence of the spread of a Mycobacterium tuberculosis strain of the Beijing genotype on Gran Canaria Island

Molecular epidemiological studies suggest that particular Mycobacterium tub erculosis strains have an enhanced capacity to spread within a community. O ne strain, the Beijing genotype, has been associated with outbreaks in a nu mber of communities throughout the world. IS6110 restriction fragment lengt h polymorphism (RFLP) analysis was performed on M. tuberculosis isolates fr om 566 of the 721 patients (78.5%) diagnosed with tuberculosis (TB) on Gran Canaria Island from 1993 to 1996, as well as 35% of isolates from 1991-199 2 (85 strains). RFLP identification of the family of strains of the Beijing genotype was confirmed by spoligotyping. Medical records of all patients w ere reviewed and epidemiological links were identified. Of 566 M. tuberculo sis isolates from 1993 to 1996 with RFLP available, 72% belonged to cluster s. The largest contained 75 cases and was caused by a strain of the Beijing genotype that was introduced to the island in 1993. It was found in 10 pat ients in 1993 (5.5%), 12 in 1994 (8.1%), 18 in 1995 (16.4%), and 35 in 1996 (27.1%). Epidemiological linkage was confirmed for 68% of cases. This stud y has demonstrated rapid dissemination of this strain of the Beijing genoty pe. This genotype might play an important role in the future of the worldwi de tuberculosis epidemic.