title: Fecal carriage and shedding density of CTX-M extended-spectrum {beta}-lactamase-producing escherichia coli in cattle, chickens, and pigs: implications for environmental contamination and food production.
abstract: The number and proportion of CTX-M positive Escherichia coli organisms were determined in feces from cattle, chickens, and pigs in the United Kingdom to provide a better understanding of the risk of the dissemination of extended-spectrum β-lactamase (ESBL) bacteria to humans from food animal sources. Samples of bovine (n = 35) and swine (n = 20) feces were collected from farms, and chicken cecal contents (n = 32) were collected from abattoirs. There was wide variation in the number of CTX-M-positive E. coli organisms detected; the median (range) CFU/g were 100 (100 × 10(6) to 1 × 10(6)), 5,350 (100 × 10(6) to 3.1 × 10(6)), and 2,800 (100 × 10(5) to 4.7 × 10(5)) for cattle, chickens, and pigs, respectively. The percentages of E. coli isolates that were CTX-M positive also varied widely; median (range) values were 0.013% (0.001 to 1%) for cattle, 0.0197% (0.00001 to 28.18%) for chickens, and 0.121% (0.0002 to 5.88%) for pigs. The proportion of animals designated high-density shedders (≥1 × 10(4) CFU/g) of CTX-M E. coli was 3/35, 15/32, and 8/20 for cattle, chickens, and pigs, respectively. We postulate that high levels of CTX-M E. coli in feces facilitate the dissemination of bla(CTX-M) genes during the rearing of animals for food, and that the absolute numbers of CTX-M bacteria should be given greater consideration in epidemiological studies when assessing the risks of food-borne transmission.
authors.affiliation: Department of Bacteriology, Veterinary Laboratories Agency, Weybridge, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom. r.horton@vla.defra.gsi.gov.uk
authors.forename: R A
authors.initials: RA
authors.lastname: Horton
authors.forename: L P
authors.initials: LP
authors.lastname: Randall
authors.forename: E L
authors.initials: EL
authors.lastname: Snary
authors.forename: H
authors.initials: H
authors.lastname: Cockrem
authors.forename: S
authors.initials: S
authors.lastname: Lotz
authors.forename: H
authors.initials: H
authors.lastname: Wearing
authors.forename: D
authors.initials: D
authors.lastname: Duncan
authors.forename: A
authors.initials: A
authors.lastname: Rabie
authors.forename: I
authors.initials: I
authors.lastname: McLaren
authors.forename: E
authors.initials: E
authors.lastname: Watson
authors.forename: R M
authors.initials: RM
authors.lastname: La Ragione
authors.forename: N G
authors.initials: NG
authors.lastname: Coldham
mesh_terms: D000818:Animals; D058491:Bacterial Load; D057138:Bacterial Shedding; D002417:Cattle; D002645:Chickens; D004783:Environmental Microbiology; D004926:Escherichia coli / Q000201:enzymology* / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology*; D005516:Food Microbiology; D006801:Humans; D013552:Swine; D006113:United Kingdom; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D001618:beta-Lactamases