title: Prevalence and antimicrobial resistance of Salmonella isolated from two pork processing plants in Alberta, Canada.
abstract: This study investigated the frequency of Salmonella serovars on pig carcasses at various processing steps in two commercial pork processing plants in Alberta, Canada and characterized phenotypic and genotypic antimicrobial resistance (AMR) and PFGE patterns of the Salmonella isolates. Over a one year period, 1000 swab samples were collected from randomly selected pigs at two slaughter plants. Sampling points were: carcass swabs after bleeding (CSAB), carcass swabs after de-hairing (CSAD, plant A) or skinning (CSASk, plant B), carcass swabs after evisceration (CSAE), carcass swabs after pasteurization (CSAP, plant A) or washing (CSAW, plants B) and retail pork (RP). For plant A, 87% of CSAB and 8% of CSAE were positive for Salmonella while at plant B, Salmonella was recovered from 94% of CSAB and 10% of CSAE. Salmonella was not recovered from the RP samples at either plant, indicating that the plants used effective control measures. Salmonella enterica serovar Derby was the most common serotype (23%, 29/127) recovered in plant A and plant B (61%, 76/124). For plant A, 35% (45/127) of isolates were resistant to at least one antimicrobial. Five isolates (3.9%), 4 serovar Ohio strains and one serovar I:Rough-O:I,v:-, strain were simultaneously resistant to antimicrobials of very high (Category I), high (Category II), and medium (Category III) importance to human medicine. The 4 S. Ohio isolates were recovered from 3 different steps of pork processing on the same sampling day and displayed resistance to 5-7 antimicrobials, with all of them displaying resistance to ceftiofur and ceftriaxone (Category I). An I:Rough-O:l,v:- isolate, recovered on a different sampling day, was resistant to 7 antimicrobials that included resistance to ampicillin/clavulanic acid, ceftiofur and ceftriaxone (Category I). Salmonella strains isolated from plant A harbored 12 different AMR genes. The most prevalent genes were sul1, sul2, tet(A), tet(B), aadA, strA/strB, aac(3)IV and aphA1. For Salmonella isolates from plant B, 7 resistance genes were identified alone or in combination where tet(B) was found in 77 (62.3%) of the isolates. For plant A, 19 different PFGE subtypes of Salmonella isolates that displayed phenotypic and/or genotypic resistance were observed while 13 different PFGE subtypes were observed for plant B. The lack of detection of Salmonella on the surfaces of RP suggests that current pork processing practices can dramatically reduce Salmonella. Salmonella isolates from pig carcasses at various steps displayed multidrug resistance, including to those of very high importance in human medicine, which represent a public health concern.
authors.affiliation: Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada.
authors.forename: Alma Fernanda
authors.initials: AF
authors.lastname: Sanchez-Maldonado
authors.affiliation: Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada.
authors.forename: Mueen
authors.initials: M
authors.lastname: Aslam
authors.affiliation: Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada.
authors.forename: Cara
authors.initials: C
authors.lastname: Service
authors.affiliation: Department of Food Science, Faculty of Agricultural and Food Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
authors.forename: Claudia
authors.initials: C
authors.lastname: Narváez-Bravo
authors.affiliation: Centre for Food-borne, Environmental Zoonotic Infectious Diseases, Public Health Agency of Canada, Guelph, Ontario N1G 5B2, Canada.
authors.forename: Brent P
authors.initials: BP
authors.lastname: Avery
authors.affiliation: National Microbiology Laboratory @ Guelph, Public Health Agency of Canada, Guelph, Ontario, N1G 3W4, Canada.
authors.forename: Roger
authors.initials: R
authors.lastname: Johnson
authors.affiliation: Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada. Electronic address: Tineke.Jones@agr.gc.ca.
authors.forename: Tineke H
authors.initials: TH
authors.lastname: Jones
mesh_terms: D000416:Alberta; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D008460:Meat / Q000382:microbiology*; D008461:Meat Products / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D012475:Salmonella / Q000187:drug effects / Q000302:isolation & purification*; D012481:Salmonella Infections, Animal / Q000453:epidemiology / Q000517:prevention & control*; D019779:Salmonella enterica / Q000187:drug effects / Q000302:isolation & purification*; D065288:Serogroup; D013552:Swine
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antimicrobial resistance; Pork; Salmonella; Slaughter plant