Effects of septic shock vasopressors on the fitness of Escherichia coli.

Norepinephrine is a catecholamine used as a first-line vasopressor in the management of sepsis. Nevertheless, norepinephrine has been shown to increase fitness and virulence of Escherichia coli, the most predominant facultative anaerobic commensal bacterium in the vertebrate intestinal microbiota and one of the bacteria most frequently implicated in sepsis. Despite high genetic diversity within E. coli species, these effects have been studied on a limited number of archetypal strains. Moreover, the fitness effect of alternative vasopressors, angiotensin II and vasopressin, has never been studied in E. coli. Here, we aimed to explore the effect of norepinephrine, vasopressin and angiotensin II on the fitness of E. coli in stressful media mimicking body compartments (serum-SAPI and urine), using a collection of 21 strains representative of the phylogenetic diversity of the species, and E. coli 536, an urosepsis model strain. We showed that norepinephrine increased the fitness of E. coli, regardless of genetic background, virulence or site of isolation, both in serum-SAPI and urine media. Unlike norepinephrine, angiotensin II and vasopressin display low or no effects on E. coli fitness. Our results bring insights on in vitro effects of norepinephrine, vasopressin and angiotensin II on E. coli, crucial for optimizing sepsis management and guiding future in vivo studies.