Pandemic Bacteremic Escherichia Coli Strains: Evolution and Emergence of Drug-Resistant Pathogens.

In recent years, there have been several pandemics of E. coli strains which are highly virulent and antibiotics resistant. Here, we discuss one recent pandemic strain, ST131. These E. coli strains are members of the virulence-associated phylogenetic group B2 and exhibit extraintestinal virulence factors, including various adhesins, toxins, siderophores, and protectins. This group often also harbors a diverse range of antimicrobial resistance types and mechanisms and may have particular metabolic capacities that enable it to colonize many individuals asymptomatically, while out competing other E. coli strains. Here, we discuss this clonal group in the context of other pathogenic E. coli and focus on its specific characteristics in terms of resistance, virulence, and metabolism.