<i>Escherichia coli</i>Sequence Type ST131 as the Major Cause of Serious Multidrug‐Resistant<i>E. coli</i>Infections in the United States

A single E. coli clonal group, ST131, probably caused the most significantly antimicrobial-resistant E. coli infections in the United States in 2007, thereby constituting an important new public health threat. Enhanced virulence and/or antimicrobial resistance compared with other E. coli, plus ongoing dissemination among locales, may underlie ST131's success. Urgent investigation of the sources and transmission pathways of ST131 is needed to inform mitigation efforts.