title: Evaluation of commonly used antimicrobial interventions for fresh beef inoculated with Shiga toxin-producing Escherichia coli serotypes O26, O45, O103, O111, O121, O145, and O157:H7.
abstract: Although numerous antimicrobial interventions targeting Escherichia coli O157:H7 have been developed and implemented to decontaminate meat and meat products during the harvesting process, the information on efficacy of these interventions against the so-called Big Six non-O157  Shiga toxin-producing E. coli (STEC) strains is limited. Prerigor beef flanks (160) were inoculated to determine if antimicrobial interventions currently used by the meat industry have a similar effect in reducing non-O157 STEC serogroups O26, O45, O103, O111, O121, and O145 compared  with E. coli O157:H7. A high (10(4) CFU/cm(2)) or a low (10(1) CFU/cm(2)) inoculation of two cocktail mixtures was applied to surfaces of fresh beef. Cocktail mixture 1 was composed of O26, O103, O111, O145, and O157, while cocktail mixture 2 was  composed of O45, O121, and O157. The inoculated fresh beef flanks were subjected to spray treatments by the following four antimicrobial compounds: acidified sodium chlorite, peroxyacetic acid, lactic acid, and hot water. High-level inoculation samples were enumerated for the remaining bacteria  populations after each treatment and compared with the untreated controls, while low-level inoculation samples were chilled for 48 h at 4°C before enrichment, immunomagnetic separation, and isolation. Spray treatments with hot water were the most effective, resulting in mean pathogen reductions  of 3.2 to 4.2 log CFU/cm(2), followed by lactic acid. Hot water and lactic acid also were the most effective interventions with the low-level inoculation on surfaces of fresh beef flanks after chilling. Peroxyacetic acid had an intermediate effect, while acidified sodium chlorite  was the least effective in reducing STEC levels immediately after treatment. Results indicate that the reduction of non-O157 STEC by antimicrobial interventions on fresh beef surfaces were at least as great as for E. coli O157:H7. However, the recovery of these low inoculation levels  of pathogens indicated that there is no single intervention to eliminate them.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE 68933-0166, USA. norasak.kalchayanand@ars.usda.gov
authors.forename: Norasak
authors.initials: N
authors.lastname: Kalchayanand
authors.forename: Terrance M
authors.initials: TM
authors.lastname: Arthur
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Bosilevac
authors.forename: John W
authors.initials: JW
authors.lastname: Schmidt
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Steven D
authors.initials: SD
authors.lastname: Shackelford
authors.forename: Tommy L
authors.initials: TL
authors.lastname: Wheeler
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle; D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D006801:Humans; D008460:Meat / Q000382:microbiology*; D012703:Serotyping; D054323:Shiga-Toxigenic Escherichia coli / Q000187:drug effects* / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents