title: Salmonella diversity and burden in cows on and culled from dairy farms in the Texas High Plains.
abstract: The objective of this study was to characterize the epidemiology of Salmonella carried by dairy cows culled from herds in the Texas High Plains. Feces were collected from a convenience sample of 706 animals culled from nine dairy farms. In addition, individually paired fecal and hide samples were collected from 70 healthy milking cows on three of the dairies. Samples were cultured for Salmonella using routine methods; isolates were serotyped and subjected to a panel of antimicrobial drugs to determine susceptibility. Salmonella was recovered from 32.6% of culled cows. Whole-herd use of a vaccine containing siderophore receptors and porin proteins was associated (p=0.05) with reduced Salmonella prevalence in that the prevalence among herds that practiced whole-herd vaccination was 8.0% compared to 36.8% among herds that did not use this vaccine. The majority (88.6%) of isolates were pansusceptible or resistant to one drug. Of the 3.1% of isolates resistant to more than four drugs, all were Salmonella Newport and were recovered from one dairy. Various serotypes were recovered from individual fecal and hide samples. Salmonella Montevideo was recovered more frequently (p<0.01) from hide samples, whereas Salmonella Cerro was recovered more frequently (p<0.01) from feces. Salmonella was recovered from at least one cow on all dairies. While our study was not a priori designed to address herd-level factors, we found evidence that the whole-herd use of a siderophore receptor and porin protein-containing vaccine might be a useful aid in the control of Salmonella in groups of cattle. As this is a nonrandomized evaluation of an intervention, other herd-level factors that may be correlated with vaccine use, such as biosecurity, might have been responsible for the observed association.
authors.affiliation: International Center for Food Industry Excellence, Department of Animal and Food Sciences, College of Agricultural Sciences and Natural Resources, Texas Tech University, Lubbock, Texas 79409-2141, USA. Guy.Loneragan@TTU.edu
authors.forename: Guy H
authors.initials: GH
authors.lastname: Loneragan
authors.forename: Daniel U
authors.initials: DU
authors.lastname: Thomson
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: McCarthy
authors.forename: Hattie E
authors.initials: HE
authors.lastname: Webb
authors.forename: Angela E
authors.initials: AE
authors.lastname: Daniels
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Edrington
authors.forename: David J
authors.initials: DJ
authors.lastname: Nisbet
authors.forename: Sara J
authors.initials: SJ
authors.lastname: Trojan
authors.forename: Shelly C
authors.initials: SC
authors.lastname: Rankin
authors.forename: Mindy M
authors.initials: MM
authors.lastname: Brashears
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D058491:Bacterial Load / Q000662:veterinary; D001425:Bacterial Outer Membrane Proteins / Q000037:antagonists & inhibitors; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors; D001428:Bacterial Vaccines / Q000276:immunology*; D002417:Cattle / Q000276:immunology / Q000382:microbiology*; D003612:Dairying; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D005243:Feces / Q000382:microbiology; D032521:Immunity, Herd; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D018272:Porins / Q000037:antagonists & inhibitors; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors; D012475:Salmonella / Q000145:classification* / Q000187:drug effects / Q000302:isolation & purification*; D012703:Serotyping / Q000662:veterinary; D012867:Skin / Q000382:microbiology; D013781:Texas
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D018272:Porins; D011956:Receptors, Cell Surface; C035902:siderophore receptors