Molecular epidemiology of tuberculosis: toy or tool? A review of the literature and examples from Central Europe.

Genotyping has become an indispensable tool in medical microbiology and epidemiology. One of the first targets has been Mycobacterium tuberculosis. Over the past 15 years approximately 900 pertinent publications have substantiated the value of the genotyping approach for tuberculosis control. New insights into the understanding of the natural history of tuberculosis, especially regarding the frequencies of reactivation, reinfection or multiple infection entailed adaptations of pathophysiological concepts. However, assessment of recent transmission, outbreak analysis, and detection of laboratory contamination still form the genuine scope of genotyping. Detection of unsuspected clusters of cases can provide clues to search for further, undetected cases. Uncovering false positive cultures spares the risks and costs of unnecessary treatment and may reveal systematic laboratory weaknesses. Several European countries already profit from nationwide prospective fingerprinting. After providing genotyping results to public health officials, these were able to document epidemiological links for substantially more tuberculosis patients. On a global scale, strain families and particular strains have been identified, characterised and traced in their spread. The importation of Beijing-genotype multidrug-resistant M. tuberculosis into Central European countries will be described here as an example. The goal for further developments is the ability to compare isolates for epidemiological purposes in a single step that also comprises species determination, drug resistance testing and detection of pathogenicity factors.