title: Short communication: Determination of Salmonella clustered regularly interspaced short palindromic repeats (CRISPR) diversity on dairy farms in Wisconsin and Minnesota.
abstract: Salmonella enterica ssp. enterica is a foodborne pathogen able to cause disease in both humans and animals. Diverse serovars of this pathogen exist, some of which are host specific, causing a range of clinical symptoms from asymptomatic infection through morbidity and mortality. According to a 2007 survey by the USDA National Animal Health Monitoring System, fecal shedding of Salmonella from healthy cows occurs on 39.7% of dairy farms in the United States. Certain serovars are frequently isolated from dairy farms and the majority of isolates from the National Animal Health Monitoring System study were represented by 5 serovars; however, genotypic diversity was not examined. The objective of this study was to determine the diversity of clustered regularly interspaced short palindromic repeats (CRISPR) loci in Salmonella collected from 8 dairy farms with a previous history of salmonellosis. None of the cows or calves sampled on 2 of the 8 dairy farms were shedding Salmonella, although Salmonella was detected in a cow bedding sample on 1 of these farms. Salmonella populations were discrete on each farm, according to CRISPR typing, with the exception of an Anatum var. 15+ type on farms 5 and 6 and the Montevideo type on farms 1 and 2. One to 4 distinct CRISPR genotypes were identified per farm. The CRISPR typing differed within serovars, as Montevideo, Anatum var. 15+, and Muenster serovars had no overlap of spacer content, even on the same farm, reflecting between- and within-serovar genetic diversity. The dynamic nature of Salmonella populations was shown in a farm that was sampled longitudinally over 13.5 mo. Changes in serovar from 3,19:-:z27 to Montevideo was observed between the first sampling time and 8 mo later, with concomitant change in CRISPR alleles. The results indicate that Salmonella strains present in smaller dairy herds (<500 head) are specific to that farm and new Salmonella strains may emerge over time.
authors.affiliation: DuPont-Nutrition and Health, 3329 Agriculture Dr., Madison, WI 53716. Electronic address: chris.wehnes@dupont.com.
authors.forename: C A
authors.initials: CA
authors.lastname: Wehnes
authors.affiliation: DuPont-Nutrition and Health, 3329 Agriculture Dr., Madison, WI 53716.
authors.forename: T G
authors.initials: TG
authors.lastname: Rehberger
authors.affiliation: DuPont-Nutrition and Health, 3329 Agriculture Dr., Madison, WI 53716.
authors.forename: R
authors.initials: R
authors.lastname: Barrangou
authors.affiliation: DuPont-Nutrition and Health, 3329 Agriculture Dr., Madison, WI 53716.
authors.forename: A H
authors.initials: AH
authors.lastname: Smith
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology; D064112:Clustered Regularly Interspaced Short Palindromic Repeats / Q000235:genetics*; D003612:Dairying; D005243:Feces / Q000382:microbiology; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D008910:Minnesota / Q000453:epidemiology; D008969:Molecular Sequence Data; D012475:Salmonella / Q000235:genetics* / Q000302:isolation & purification; D012478:Salmonella Food Poisoning / Q000453:epidemiology* / Q000382:microbiology; D012481:Salmonella Infections, Animal / Q000453:epidemiology* / Q000382:microbiology; D017422:Sequence Analysis, DNA; D065288:Serogroup; D014922:Wisconsin / Q000453:epidemiology
keywords: clustered regularly interspaced short palindromic repeats (CRISPR); cow; salmonellosis