title: Marked increase in incidence for bloodstream infections due to Escherichia coli, a side effect of previous antibiotic therapy in the elderly.
abstract: We conducted a survey including 3334 bloodstream infections (BSIs) due to E. coli diagnosed in 2005-2014 at a stable cohort of hospitals. Marked increases in incidence were observed for community-acquired (CA) BSIs in patients aged >75 years, CA-BSIs of digestive origin in patients aged 60-74 years, healthcare-associated BSIs, and BSIs associated with ESBL (extended-spectrum B-lactamase)-producing E. coli (ESBLEc). Using MLST, we studied the genetic diversity of 412 BSI isolates recovered during the 2014 survey: 7 major sequence type complexes (STCs) were revealed in phylogenetic group B2, 3 in group A/B1 and 2 in group D. Among the 31 ESBLEc isolates, 1/3 belonged to STC 131. We searched for possible associations between clonal groups, clinical determinants and characteristics of BSIs: isolates from groups B2 (except STC 131) and D were susceptible to antibiotics and associated with BSIs of urinary origin in patients <60 years. STC 131 and group A/B1 isolates were multi-drug resistant and associated with CA-BSIs of digestive origin in patients aged 60-74 with a recent history of antibiotic treatment. STC 131 isolates were associated with HCA-BSIs in patients with recent/present hospitalization in a long-stay unit. We provide a unique population-based picture of the epidemiology of E. coli BSI. The aging nature of the population led to an increase in the number of cases caused by the B2 and D isolates generally implicated in BSIs. In addition, the association of a trend toward increasing rates of gut colonization with multi drug-resistant isolates revealed by the rise in the incidence of BSIs of digestive origin caused by STC 131 and A/B1 (STCs 10, 23, and 155) isolates, and a significant increase in the frequency of BSIs in elderly patients with recent antibiotic treatment suggested that antibiotic use may have contributed to the growing incidence of BSI.
authors.affiliation: Service de Bactériologie et Hygiène, Centre Hospitalier Universitaire de Tours, UMR 1282 Tours, France ; Réseau des Hygiénistes du Centre, Centre Hospitalier Universitaire de Tours France.
authors.forename: Nathalie L
authors.initials: NL
authors.lastname: van der Mee-Marquet
authors.affiliation: Service of Hospital Preventive Medicine, Lausanne University Hospital Lausanne, Switzerland.
authors.forename: Dominique S
authors.initials: DS
authors.lastname: Blanc
authors.affiliation: Service d'Hygiéne Hospitaliére, Centre Hospitalier Universitaire de Besançon, UMR CNRS 6249, Chrono-environnement, Université Bourgogne Framche-Comté Besançon, France.
authors.forename: Houssein
authors.initials: H
authors.lastname: Gbaguidi-Haore
authors.affiliation: Service de Bactériologie et Hygiène, Centre Hospitalier Universitaire de Tours, UMR 1282 Tours, France.
authors.forename: Sandra
authors.initials: S
authors.lastname: Dos Santos Borges
authors.affiliation: Service de Bactériologie et Hygiène, Centre Hospitalier Universitaire de Tours, UMR 1282 Tours, France.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Viboud
authors.affiliation: Service d'Hygiéne Hospitaliére, Centre Hospitalier Universitaire de Besançon, UMR CNRS 6249, Chrono-environnement, Université Bourgogne Framche-Comté Besançon, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Bertrand
authors.affiliation: Service de Bactériologie et Hygiène, Centre Hospitalier Universitaire de Tours, UMR 1282 Tours, France.
authors.forename: Roland
authors.initials: R
authors.lastname: Quentin
keywords: Escherichia coli; ST 131; antibiotic; bloodstream infection; elderly