title: Prevalence and characterization of ESBL- and AmpC-producing Enterobacteriaceae on retail vegetables.
abstract: In total 1216 vegetables obtained from Dutch stores during 2012 and 2013 were analysed to determine the prevalence of 3rd-generation cephalosporin (3GC) resistant bacteria on soil-grown fresh produce possibly consumed raw. Vegetables grown conventionally and organically, from Dutch as well as foreign origin were compared. Included were the following vegetable types; blanched celery (n=192), bunched carrots (n=190), butterhead lettuce (n=137), chicory (n=96), endive (n=188), iceberg lettuce (n=193) and radish (n=120). Overall, 3GC-resistant Enterobacteriaceae were detected on 5.2% of vegetables. Based on primary habitat and mechanism of 3GC-resistance, these bacteria could be divided into four groups: ESBL-producing faecal species (Escherichia coli, Enterobacter spp.), AmpC-producing faecal species (Citrobacter freundii, Enterobacter spp.), ESBL-producing environmental species (Pantoea spp., Rahnella aquatilis, Serratia fonticola), and AmpC-producing environmental species (Cedecca spp., Hafnia alvei, Pantoea spp., Serratia plymuthica), which were detected on 0.8%, 1.2%, 2.6% and 0.4% of the vegetables analysed, respectively. Contamination with faecal 3GC-resistant bacteria was most frequently observed in root and bulb vegetables (average prevalence 4.4%), and less frequently in stem vegetables (prevalence 1.6%) and leafy greens (average prevalence 0.6%). In Dutch stores, only four of the included vegetable types (blanched celery, bunched carrots, endive, iceberg lettuce) were available in all four possible variants: Dutch/conventional, Dutch/organic, foreign/conventional, foreign/organic. With respect to these vegetable types, no statistically significant difference was observed in prevalence of 3GC-resistant Enterobacteriaceae between country of origin or cultivation type (5.2%, 5.7%, 5.7% and 3.3%, respectively). Vegetables consumed raw may be a source of dissemination of 3GC-resistant Enterobacteriaceae and their resistance genes to humans. The magnitude of the associated public health risk presumably depends on the types of bacteria that are ingested, i.e., faecal or environmental species, and may therefore be higher for root and bulb vegetables compared to leafy greens.
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands. Electronic address: angela.van.hoek@rivm.nl.
authors.forename: Angela H A M
authors.initials: AH
authors.lastname: van Hoek
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Christiaan
authors.initials: C
authors.lastname: Veenman
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Wendy M
authors.initials: WM
authors.lastname: van Overbeek
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Gretta
authors.initials: G
authors.lastname: Lynch
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands; Faculty of Veterinary Medicine, Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, The Netherlands.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: de Roda Husman
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Hetty
authors.initials: H
authors.lastname: Blaak
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D002511:Cephalosporins; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004755:Enterobacteriaceae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D005506:Food Contamination / Q000032:analysis*; D006801:Humans; D009426:Netherlands; D015995:Prevalence; D014675:Vegetables / Q000382:microbiology*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D002511:Cephalosporins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases
keywords: Conventional; E. coli; Fresh produce; Organic; Supermarket