RDRioMycobacterium tuberculosis lineage in the Brazil/Paraguay/Argentina triple border

The high tuberculosis (TB) incidence rates, the closeness of the cities and the high migration flux on the Brazil/Paraguay/Argentina border deserves an in-depth study, using Mycobacterial Interspersed Repetitive Unit (MIRU) and Spoligotyping genetic markers to explore the impact of the Mycobacterium tuberculosis RDRio lineage on disease transmission and resistance to anti-TB drugs in this setting. Although without the totality of M. tuberculosis isolates causing TB in this studied setting, a number of 97 isolates obtained from sputa samples culture of patients with confirmed TB, from 2013 to 2015, were submitted to 24 loci MIRU, Spoligotyping, detection of RDRio lineage and detection of mutation related to isoniazid and rifampicin resistance by MTBDRplus/DNA STRIP. In this sample, it was observed high clonal variability of circulating M. tuberculosis isolates causing TB in Brazilian cities bordering Paraguay and Argentina. The percentage of RDRio lineage causing TB in this setting was 15.46%, and lower than the detected in different areas of Brazil. According to 24 loci MIRU, the major MIRU International Type (MIT) related with RDRio lineage were MIT 26, MIT 738, MIT 601 with four, two and one isolates, respectively. Eight isolates with RDRio marker were classified as orphans. The mainly Spoligofamily related with RDRio lineage was LAM1 and LAM9 and no relationship between RDRio lineage and resistance in M. tuberculosis isolates circulating in this setting could be established. This work is pioneer in studying the dynamics of RDRio lineage transmission on the Brazil/Paraguay/Argentina border and deserves further studies to analyze the real contribution of the RDRio lineage in outbreaks and the risk of significant development of MDR-TB in the setting studied.