title: Unexpected common occurrence of transferable extended spectrum cephalosporinase-producing Escherichia coli in Swedish surface waters used for drinking water supply.
abstract: The presence of Enterobacteriaceae producing extended spectrum beta-lactamases (ESBL) or transferable AmpC beta-lactamases (pAmpC) is increasingly being reported in humans, food-producing animals and food world-wide. However, the occurrence and impact of these so-called extended spectrum cephalosporinase (ESC)-producing Enterobacteriaceae in aquatic environments are poorly documented. This study investigated the occurrence, concentrations and characteristics of ESC-producing E. coli (ESC-Ec) in samples of surface water collected at five Swedish water treatment plants that normally have relatively high prevalence and concentration of E. coli in surface water. ESC-Ec was found in 27 of 98 surface water samples analysed. All but two positive samples were collected at two of the water treatment plants studied. The ESC-Ec concentration, 1-3cfu/100mL, represented approximately 4% of the total amount of E. coli in the respective surface water sample. In total, 74% of the isolates were multi-resistant, but no isolate was resistant to carbapenems. Six types of ESBL/pAmpC genes were found in the 27 E. coli isolates obtained from the positive samples, of which four (blaCTX-M-15, blaCMY-2, blaCTX-M-1and blaCTX-M-14) were found during the whole sampling period, in samples taken at more than one water treatment plant. In addition, the genes were situated on various types of plasmids and most E. coli isolates were not closely related with regard to MLST types. The combinations of ESBL/pAmpC genes, plasmids and E. coli isolates were generally similar to those found previously in healthy and sick individuals in Sweden. In conclusion, the occurrence of ESC-Ec in Swedish surface water shows that resistant bacteria of clinical concern are present in aquatic environments even in a low-prevalence country such as Sweden.
authors.affiliation: National Food Agency, Box 622, SE-75126 Uppsala, Sweden. Electronic address: mia.egervarn@slv.se.
authors.forename: Maria
authors.initials: M
authors.lastname: Egervärn
authors.affiliation: National Veterinary Institute (SVA), SE-75189 Uppsala, Sweden.
authors.forename: Stina
authors.initials: S
authors.lastname: Englund
authors.affiliation: National Food Agency, Box 622, SE-75126 Uppsala, Sweden.
authors.forename: Marianne
authors.initials: M
authors.lastname: Ljunge
authors.affiliation: National Food Agency, Box 622, SE-75126 Uppsala, Sweden.
authors.forename: Christer
authors.initials: C
authors.lastname: Wiberg
authors.affiliation: National Veterinary Institute (SVA), SE-75189 Uppsala, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Finn
authors.affiliation: National Food Agency, Box 622, SE-75126 Uppsala, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Lindblad
authors.affiliation: National Veterinary Institute (SVA), SE-75189 Uppsala, Sweden.
authors.forename: Stefan
authors.initials: S
authors.lastname: Börjesson
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D002510:Cephalosporinase / Q000378:metabolism*; D060766:Drinking Water / Q000382:microbiology*; D004784:Environmental Monitoring; D004926:Escherichia coli; D058885:Multilocus Sequence Typing; D013548:Sweden; D014871:Water Microbiology; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D060766:Drinking Water; D002510:Cephalosporinase; C048795:AmpC beta-lactamases; D001618:beta-Lactamases
keywords: Antibiotic resistance; ESBL-Producing E. coli; Extended-spectrum cephalosporinase (ESC); Surface water; Water treatment plant; pAmpC-Producing E. coli