title: Free water surface constructed wetlands limit the dissemination of extended-spectrum beta-lactamase producing Escherichia coli in the natural environment.
abstract: The fates of Escherichia coli and extended-spectrum beta-lactamase-producing E. coli (ESBL E. coli) were studied over a period of one year in a free water surface constructed wetland (FWS CW) with a succession of open water zones and vegetation ponds (Typha or Phragmites), that received the effluent from a wastewater treatment plant. ESBL E. coli were detected and isolated from all sampling areas of the FWS CW throughout the study period. They represented 1‰ of the total E. coli population regardless of the origin of samples. Two main factors affected the log removal of E. coli and of ESBL E. coli: the season and the presence of vegetation. Between the inlet and the outlet of the FWS CW, the log removal of E. coli ranged from 1.5 in the warmer season (summer and fall) to 3.0 in the colder season (winter and spring). The concentrations of E. coli decreased significantly in the vegetated areas during the colder season, but increased in the warmer season, suggesting an effect of the plant growth stage on the survival of E. coli. Among the 369 ESBL E. coli isolates collected during our study, 84% harbored the CTX-M-ESBL type and 55.3% carried bla genes on plasmid DNA. Furthermore, 93% of the ESBL E. coli isolates were multidrug resistant but the proportion of resistant strains did not change significantly along the FWS CW. ESBL E. coli were characterized by MLST analysis using the 7 genes based Achtman Scheme. ESBL E. coli isolated from water, sediments, roots and feces of myocastors collected in the FWS CW and in the recipient river were genotypically related, suggesting persistence and circulation of the ESBL producing E. coli throughout the FWS CW and in the receiving river. Overall, these observations show that FWS CW could be an efficient treatment for ESBL E. coli disinfection of wastewater and could limit their dissemination in the aquatic environment.
authors: Irstea, UR OPAALE, 17 Avenue de Cucillé-CS 64427, F-35044 Rennes, France; Univ Bretagne Loire, France.
authors: Anne-Laure
authors: AL
authors: Vivant
authors: Irstea, UR MAEP, CS 70077, F-69626 Villeurbanne, France.
authors: Catherine
authors: C
authors: Boutin
authors: Irstea, UR MAEP, CS 70077, F-69626 Villeurbanne, France.
authors: Stéphanie
authors: S
authors: Prost-Boucle
authors: Irstea, UR MAEP, CS 70077, F-69626 Villeurbanne, France.
authors: Sandrine
authors: S
authors: Papias
authors: INRA, UMR1347 Agroécologie, BP 86510, F-21000 Dijon, France.
authors: Alain
authors: A
authors: Hartmann
authors: INRA, UMR1347 Agroécologie, BP 86510, F-21000 Dijon, France.
authors: Géraldine
authors: G
authors: Depret
authors: Irstea, UR OPAALE, 17 Avenue de Cucillé-CS 64427, F-35044 Rennes, France; Univ Bretagne Loire, France.
authors: Christine
authors: C
authors: Ziebal
authors: Irstea, UR OPAALE, 17 Avenue de Cucillé-CS 64427, F-35044 Rennes, France; Univ Bretagne Loire, France.
authors: Sophie
authors: S
authors: Le Roux
authors: Irstea, UR OPAALE, 17 Avenue de Cucillé-CS 64427, F-35044 Rennes, France; Univ Bretagne Loire, France. Electronic address: anne-marie.pourcher@irstea.fr.
authors: Anne-Marie
authors: AM
authors: Pourcher
mesh_terms: D004926:Escherichia coli / Q000302:isolation & purification*; D004927:Escherichia coli Infections; D058885:Multilocus Sequence Typing; D014867:Water / Q000494:pharmacology; D053833:Wetlands; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D014867:Water; D001618:beta-Lactamases
keywords: Antibiotic resistance; Constructed wetland; Escherichia coli; Extended-spectrum beta-lactamase; Tertiary treatment; Water