Population Dynamics of Escherichia coli Causing Bloodstream Infections over Extended Time Periods

Escherichia coli is a leading cause of community-acquired and health care-associated bloodstream infections (BSIs) worldwide. Limited information is available regarding the changes in population dynamics of human E. coli over extended time periods, especially among nonbiased E. coli isolates in large well-defined geographical regions. Coque and colleagues (I. Rodríguez, A. S. Figueiredo, M. Sousa, S. Aracil-Gisbert, et al., mSphere 6:e00868-21, 2021, https://doi.org/10.1128/msphere.00868-21) conducted a longitudinal study of E. coli BSIs in a Madrid hospital over a 21-year period (1996 to 2016). Certain E. coli B2 phylogroups (i.e., ST131 and ST73) dominated the community E. coli population in Madrid. These community clones were often introduced into the hospital setting. This study and other longitudinal surveys from England and Canada showed that ST131 subclades C1 and C2 were mainly responsible for the increase in fluoroquinolone and cephalosporin resistance among E. coli during the mid- to late 2000s.