Comparison between spoligotyping and IS6110 restriction fragment length polymorphisms in molecular genotyping analysis of Mycobacterium tuberculosis strains

Spoligotyping was compared with RFLP fingerprinting analysis in the identification of Mycobacterium tuberculosis strains. Spoligotyping sensitivity was 97.6% with a specificity of 47%. The global probability for two strains clustered with spoligotyping to be clustered also with RFLP analysis was 33%; the probability for two strains clustered with RFLP analysis to be clustered also with spoligotyping analysis was 95%. However, comparing the two methods in five outbreak episodes, full concordance was evidenced between spoligotyping and RFLP. Moreover, we evaluated the presence of our 17 largest spoligotyping clusters in spoligotyping databases from Caribbean countries, London and Cuba. Only five out of 17 patterns were present in all the cohorts. The conditional probability comparing spoligotyping and RFLP methods related to these patterns resulted in very low concordance (range from 2 to 38%). In conclusion, we confirm that spoligotyping when used alone overestimates the number of recent transmission and does not represent a suitable method for wide clinical practice application. However, it allows to get a first good picture of strain identity in a new setting and in more localized or confined settings, the probability of reaching the same result compared to RFLP was 100% confirming the usefulness of spoligotyping in the management of epidemic events, especially in hospitals, prisons and close communities.