Suspected cases of ST homoplasy in Burkholderia pseudomallei

In this study, we used whole-genome sequencing to identify the first reported instances of intracontinental ST homoplasy from ST-722 and ST-804 B. pseudomallei isolates separated by large geographic distances. In contrast, we identified an unusual long-range (460km) dispersal of ST-149, which occurred between a remote Australian island and the Australian mainland, indicating recent importation of this ST into a new region. Our results show that, whilst a highly useful and portable method, MLST can lead to erroneous conclusions about isolate origin and disease attribution. In cases where a shared ST is identified between geographically distant locales, whole-genome sequencing should be used to resolve strain origin.