Bhutan is a lower middle-income country in South Asia, sandwiched between China and the northwest Indian states of Assam and West Bengal. In close proximity to Nepal ( < 70 km of Indian territory separates the two countries), Bhutan is a Himalayan nation with an estimated population of 750 000 people, of which the majority (69 %) live in remote rural locations (Office of the Census Commissioner – Royal Government of Bhutan, 2006). Like other low-income countries in the region, diarrhoeal disease is a major public health problem in Bhutan, and both S. flexneri and S. sonnei are endemic (Marfin et al., 1994; Ruekit et al., 2014). Between March 2011 and October 2013, a diarrhoeal disease surveillance study was conducted in the Bhutanese capital, Thimphu. During this study, there was an increased number of S. sonnei isolated between June and July. Antimicrobial susceptibility testing, PFGE and plasmid replicon typing of 29 of these S. sonnei isolates showed that all were identical by PFGE pattern and antimicrobial susceptibility (Ruekit et al., 2014). All these S. sonnei isolates were resistant to ciprofloxacin (MIC ≥ 3 μg μl− 1), which was infrequently observed in strains circulating globally during the same period (Ruekit et al., 2014). This study suggested that these S. sonnei isolates were closely related and may have been a recent introduction into Bhutan.