Vaccine-induced Immunity Circumvented by Typical Mycobacterium tuberculosis Beijing Strains
Figure 1. Correlation between the multiplex PCR results and insertion sequence (IS)6110 restriction fragment length polymorphism (RFLP) pattern similarity. On the basis of IS6110 RFLP pattern similarity, 3 groups of related patterns (A, B, and C) were recognized among 410 Mycobacterium tuberculosis Beijing clade strains isolated in the Netherlands. The similarity of the IS6110 RFLP patterns of groups B (61%–73%) and C (50%) are relative to the RFLP patterns of group A. Within group C the similarity of the patterns was at least 58%. By using an IS6110 RFLP similarity of 73% as cutoff (which defined the most homogeneous IS6110 RFLP group [group A]), 321 (98.2%) of 327 Beijing strains were consistently identified as typical Beijing, and 81 (97.6%) of the 83 remaining Beijing clade strains were classified as atypical Beijing by the multiplex PCR. The κ value for agreement between the tests is 0.922.