Sub-Iliac Lymph Nodes at Slaughter Lack Ability to PredictSalmonella entericaPrevalence for Swine Farms

Abstract

The aim of this study was to assess the value of deep systemic sub-iliac lymph nodes collected at slaughter as predictors of Salmonella prevalence in live hogs.An observational study was conducted on 24 farms fromSeptember 2006 to February 2009. At least one cohort of market-weight pigs was visited for each farm. Within each cohort, 30 farm fecal samples on farm and 30 sub-iliac lymph nodes from matched pigs at slaughter were collected. Samples were cultured for Salmonella enterica and serotyped by conventionalmethods. Overall, 3.4%(51 of 1490) of farmfeces and 0.06% (1 of 1739) of sub-iliac lymph nodes were Salmonella positive; 71.4% (15 of 21) of farms had at least one positive fecal sample, and 4.2% (1 of 24) had at least one positive sub-iliac lymph node. The median within-farm prevalence of Salmonella in farm fecal samples was 1.7%, ranging from 0% to 38.3%; for sub-iliac lymph nodes the median was 0%, ranging from 0% to 1.1%. The median within-cohort prevalence in farm fecal samples was 0%, ranging from0%to 43.3%; for sub-iliac lymph nodes the median was 0%, ranging from0%to 4%. The predominant serotype detected was Derby, followed by Anatum and Typhimurium (Copenhagen). Salmonella Braenderup was recovered from the sub-iliac lymph node. The low detection rate of Salmonella in sub-iliac lymph nodes (0.06%) limits its usefulness as a dependable predictor of Salmonella contamination originating on farm (3.4%). RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. The aim of this study was to assess the value of deep systemic sub-iliac lymph nodes collected at slaughter as predictors of Salmonella prevalence in live hogs. An observational study was conducted on 24 farms from September 2006 to February 2009. At least one cohort of market-weight pigs was visited for each farm. Within each cohort, 30 farm fecal samples on farm and 30 sub-iliac lymph nodes from matched pigs at slaughter were collected. Samples were cultured for Salmonella enterica and serotyped by conventional methods. Overall, 3.4% (51 of 1490) of farm feces and 0.06% (1 of 1739) of sub-iliac lymph nodes were Salmonella positive; 71.4% (15 of 21) of farms had at least one positive fecal sample, and 4.2% (1 of 24) had at least one positive sub-iliac lymph node. The median within-farm prevalence of Salmonella in farm fecal samples was 1.7%, ranging from 0% to 38.3%; for sub-iliac lymph nodes the median was 0%, ranging from 0% to 1.1%. The median within-cohort prevalence in farm fecal samples was 0%, ranging from 0% to 43.3%; for sub-iliac lymph nodes the median was 0%, ranging from 0% to 4%. The predominant serotype detected was Derby, followed by Anatum and Typhimurium (Copenhagen). Salmonella Braenderup was recovered from the sub-iliac lymph node. The low detection rate of Salmonella in sub-iliac lymph nodes (0.06%) limits its usefulness as a dependable predictor of Salmonella contamination originating on farm (3.4%).

Salmonella enterica in Swine Production: Assessing the Association between Amplified Fragment Length Polymorphism and Epidemiological Units of Concern

“…This study was a post hoc analysis using Salmonella isolates collected for a project with different purposes, for which the epidemiological unit of concern was known. Details of the project have been published elsewhere (23). Briefly, 27 farms located in the midwestern United States agreed to participate during the study period of September 2006 to February 2009.…”

“…The mesenteric lymph nodes were held on ice and transported to the laboratory, where they were refrigerated until processing the next day. It was anticipated that fecal and mesenteric lymph node samples would be collected from four harvest cohorts of pigs for each farm (23). The visits for 4 cohorts within each farm were scheduled at least 1 month apart.…”

Prevalencia de Salmonella spp., en ganglios mesentéricos de porcinos en plantas de beneficio Colombianas

“…Additionally, it is indicated when strain origin source requires to be determined starting from the farm (31). Moreover, more studies recommend molecular techniques, for this study the 3M™ Molecular Detection Assay 2-Salmonella was of great use, since no inhibitions nor false negative were present (data not shown) (32 Por último, la detección de Salmonella en ganglios linfáticos es pertinente, pues ésta muestra permite detectar si la fuente de origen es el cerdo y no una fuente ambiental, adicionalmente es indicada cuando se quiere determinar el origen de la cepa desde la granja (31). Por otra parte, cada vez son más los estudios que recomiendan el uso de técnicas moleculares, en este estudio resultó de gran utilidad el uso del sistema 3M™ Molecular Detection Assay 2-Salmonella; ya que no se presentaron inhibiciones ni resultados falsos negativos (datos no mostrados), (32).…”

Use of bioinformatic SNP predictions in differentially expressed genes to find SNPs associated with Salmonella colonization in swine

“…A recent survey of Salmonella incidence in swine farms in Iowa, USA, resulted in the collection of tissues and Salmonella faecal shedding data for >7000 animals (Wang et al. 2010).…”

“…Furthermore, a survey carried out by the Collaboration of Animal Health and Food Safety Epidemiology showed in 2005 that approximately 58% of pig farm sites sampled in five states of the United States were positive for Salmonella . Most recently, a study conducted on 24 hog‐farms in Iowa during 2006–09 found that 71.4% of farms had at least one Salmonella ‐positive faecal sample (Wang et al. 2010).…”