Clusters of Drug-Resistant Mycobacterium tuberculosis Detected by Whole-Genome Sequence Analysis of Nationwide Sample, Thailand, 2014–2017

• Main Authors: Ditthawat Nonghanphithak, Angkana Chaiprasert, Saijai Smithtikarn, Phalin Kamolwat, Petchawan Pungrassami, Virasakdi Chongsuvivatwong, Surakameth Mahasirimongkol, Wipa Reechaipichitkul, Chaniya Leepiyasakulchai, Jody E. Phelan, David Blair, Taane G. Clark, Kiatichai Faksri
• Format: Article
• Language: English
• Published: Centers for Disease Control and Prevention 2021-03-01
• Series: Emerging Infectious Diseases
• Subjects: Mycobacterium tuberculosis; drug resistance; multidrug-resistant TB; transmission; whole-genome sequencing; Thailand
• Online Access: https://wwwnc.cdc.gov/eid/article/27/3/20-4364_article

Multidrug-resistant tuberculosis (MDR TB), pre-extensively drug-resistant tuberculosis (pre-XDR TB), and extensively drug-resistant tuberculosis (XDR TB) complicate disease control. We analyzed whole-genome sequence data for 579 phenotypically drug-resistant M. tuberculosis isolates (28% of available MDR/pre-XDR and all culturable XDR TB isolates collected in Thailand during 2014–2017). Most isolates were from lineage 2 (n = 482; 83.2%). Cluster analysis revealed that 281/579 isolates (48.5%) formed 89 clusters, including 205 MDR TB, 46 pre-XDR TB, 19 XDR TB, and 11 poly–drug-resistant TB isolates based on genotypic drug resistance. Members of most clusters had the same subset of drug resistance-associated mutations, supporting potential primary resistance in MDR TB (n = 176/205; 85.9%), pre-XDR TB (n = 29/46; 63.0%), and XDR TB (n = 14/19; 73.7%). Thirteen major clades were significantly associated with geography (p<0.001). Clusters of clonal origin contribute greatly to the high prevalence of drug-resistant TB in Thailand.