Prevalence of Latin-American-Mediterranean genetic family in population structure of Mycobacterium tuberculosis in Bulgaria

Tuberculosis (TB) control remains an important public health priority for Bulgaria. The population structure of Mycobacterium tuberculosis is clonal and certain genetic families of this species (e.g., Latin-American-Mediterranean [LAM]) have attracted more attention due to their global dissemination and/or particular pathogenic properties, e.g., association with multidrug resistance (MDR). The aim of this study was to evaluate the prevalence of the M. tuberculosis LAM family in Bulgaria based on the use of different molecular markers. A total of 101 previously spoligotyped M. tuberculosis strains were studied by LAM-specific PCR assay to detect an insertion of IS6110 in the specific genome region. On the whole, clear-cut results were obtained for most strains; spoligotype-based family was reassigned in some of them. At the same time, double bands were amplified in some cases and warrant further validation studies of this method. The higher MDR rate among LAM versus other genotype isolates was observed (P = 0.04). In conclusion, these results suggest a low (<4%) prevalence rate of LAM in Bulgaria (that is similar to its Balkan neighbors) and highlight the importance of using robust markers for correct detection of the LAM family.