Genetic diversity of the Mycobacterium tuberculosis East African-Indian family in three tropical Asian countries

[[abstract]]AbstractBackground The Beijing lineage of Mycobacterium tuberculosis (MTB) is the most predominant MTB strain in Asian countries and is spreading worldwide, but the East African-Indian (EAI) lineage is also particularly prevalent in many tropical Asian countries. The evolutionary relationships among MTB EAI isolates from Taiwan and those of tropical Asian countries remain unknown. Methods The EAI strains collected from patients in Taiwan by using spoligotyping and MIRU-VNTR typing were compared to published profiles from Cambodia and Singapore to investigate potential epidemiological linkages. Results Among the three countries, the EAI lineage was most prevalent in Cambodia (60%; Singapore, 25.62%; and Taiwan, 21.85%), having also the highest rates of multi-drug resistance (MDR) and lowest rates of clustering of MTB isolates. Also, we describe a convenient method using 7 selected MIRU-VNTR loci for first-line typing to discriminate Beijing and EAI lineages. A potential epidemiological linkage in these tropical Asian countries is also discussed based on a minimum-spanning tree (MST) constructed using 24 MIRU-VNTR loci of MTB EAI strains. Conclusion This study identified evolutionary relationships among MTB EAI isolates from Taiwan and those of two other tropical Asian countries, Cambodia and Singapore