Genetic diversity and distribution dynamics of multidrug-resistant Mycobacterium tuberculosis isolates in Nepal

Multidrug-resistant tuberculosis (MDR-TB) is an emerging public health problem in Nepal. Despite the implementation of a successful TB control program in Nepal, notifications of MDR-TB are increasing, yet the reasons are unknown. The objective of this study was to understand the genetic diversity and epidemiological characteristics of MDR-Mycobacterium tuberculosis (MTB) isolates in Nepal. We isolated and genotyped 498 MDR-MTB isolates collected from April 2009 to March 2013 and analyzed the patients' background information. Our results showed that the lineage 2 (Beijing family) was the most predominant lineage (n = 241; 48.4%), followed by lineage 3 (n = 153, 30.7%). Lineage 4 was the third most prevalent (n = 73, 14.5%) followed by lineage 1 (n = 32, 6.4%). The lineages were significantly associated with geographic region, ethnic group, age and sex of patients. The Beijing genotype was found to have an important role in transmitting MDR-TB in Nepal and was significantly associated with the eastern region, mongoloid ethnic group and younger age group. We conclude that early diagnosis and treatment including molecular-epidemiological surveillance of MDR-TB cases will help to control transmission of MDR-TB in Nepal.