State of the art: typing Mycobacterium tuberculosis.

After years of decline, infections due to Mycobacterium tuberculosis appear to be increasing in the developed world. This has led to a search for improved methods of typing strains in order to answer new questions concerning the epidemiology of tuberculosis. Owing to the phenotypic and genotypic homogeneity of the species, classical fingerprinting methods, including phage typing, serotyping and multilocus enzyme electrophoresis, have proven ineffective. However, new methods based on the analysis of repetitive DNA sequences have been introduced and are now being used to elucidate the emerging pattern of disease.