Evolution of bacterial pathogenesis (2014-2016)

Little is known regarding the specific evolutionary steps involved in the emergence of highly virulent microbial pathogens from benign or mildly virulent populations. The group A streptococcus is exemplary of this vexing problem - a large population reservoir of bacteria exists causing only mild infections and a highly virulent strain emerges causing significant disease and mortality. Utilising an extensive WHO reference collection of group A streptococcus isolates, we shall define the evolutionary events that produced the most significant invasive strain designated M1T1. The M1T1 strain emerged in the mid-1980s, has since disseminated globally, yet the evolutionary sequence of events resulting in this emergence are largely unknown.