title: Survival of pathogenic Escherichia coli on basil, lettuce, and spinach.
abstract: The contamination of lettuce, spinach and basil with pathogenic E. coli has caused numerous illnesses over the past decade. E. coli O157:H7, E. coli O104:H4 and avian pathogenic E. coli (APECstx- and APECstx+) were inoculated on basil plants and in promix substrate using drip and overhead irrigation. When overhead inoculated with 7 log CFU/ml of each strain, E. coli populations were significantly (P = 0.03) higher on overhead-irrigated plants than on drip-irrigated plants. APECstx-, E. coli O104:H4 and APECstx+ populations were recovered on plants at 3.6, 2.3 and 3.1 log CFU/g at 10 dpi (days post-inoculation), respectively. E. coli O157:H7 was not detected on basil after 4 dpi. The persistence of E. coli O157:H7 and APECstx- were similar when co-inoculated on lettuce and spinach plants. On spinach and lettuce, E. coli O157:H7 and APEC populations declined from 5.7 to 6.1 log CFU/g and 4.5 log CFU/g, to undetectable at 3 dpi and 0.6-1.6 log CFU/g at 7 dpi, respectively. The detection of low populations of APEC and E. coli O104:H4 strains 10 dpi indicates these strains may be more adapted to environmental conditions than E. coli O157:H7. This is the first reported study of E. coli O104:H4 on a produce commodity.
authors.affiliation: Department of Animal and Food Sciences, University of Delaware, Newark, DE, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Markland
authors.forename: K L
authors.initials: KL
authors.lastname: Shortlidge
authors.forename: D G
authors.initials: DG
authors.lastname: Hoover
authors.forename: S
authors.initials: S
authors.lastname: Yaron
authors.forename: J
authors.initials: J
authors.lastname: Patel
authors.forename: A
authors.initials: A
authors.lastname: Singh
authors.forename: M
authors.initials: M
authors.lastname: Sharma
authors.forename: K E
authors.initials: KE
authors.lastname: Kniel
mesh_terms: D057914:Agricultural Irrigation; D000818:Animals; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004926:Escherichia coli / Q000502:physiology*; D019453:Escherichia coli O157 / Q000502:physiology; D005506:Food Contamination; D005516:Food Microbiology; D006801:Humans; D018545:Lactuca / Q000382:microbiology*; D018649:Ocimum basilicum / Q000382:microbiology*; D018724:Spinacia oleracea / Q000382:microbiology*
keywords: E. coli; avian pathogenic E. coli; basil; irrigation; lettuce; persistence; promix; spinach; survival