Whole genome sequencing analysis of multidrug-resistant tuberculosis in Singapore, 2006-2018

There were 290 multidrug-resistant (MDR)-TB cases diagnosed in Singapore from 2006 to 2018. Eighty-one percent were foreign-born. Spoligotyping and MIRU-VNTR methods identified 108 patients in 24 clusters. The Beijing spoligotype accounted for 22 clusters. Whole genome sequencing (WGS) analysis reduced the number of clustered patients and clusters to 43 and nine respectively. One MIRU cluster was redefined into three WGS clusters. All the clusters had foreign-born source cases. Forty percent of local-born, versus 9% of foreign-born, MDR-TB cases belonged to WGS clusters. WGS more accurately elucidated potential MDR-TB transmission which was overestimated by conventional genotyping methods in Singapore.