Isolation and characterization of Yersinia enterocolitica from swine feces recovered during the National Animal Health Monitoring System Swine 2000 study

Abstract

A national study was conducted for the isolation of pathogenic Yersinia enterocolitica in pig feces in the United States as part of the National Animal Health Monitoring System's Swine 2000 study. Fecal samples collected from swine operations from September 2000 to March 2001 from 77 production sites in 15 of the top 17 swine-producing states were tested for the presence of pathogenic Y. enterocolitica. After enrichment of swine fecal samples in irgasan-ticarcillin- potassium chlorate broth, the enriched cultures were plated on cefsulodin-irgasan-novobiocin agar for isolation of presumptive Y. enterocolitica. The isolates were confirmed as pathogenic Y. enterocolitica by the fluorogenic 5′ nuclease PCR assay targeting the chromosomal attachment invasion ail gene. Of 2,793 fecal samples tested, 106 (3.80%) ail-positive strains of Y. enterocolitica were isolated. These 106 ail-positive isolates originated from 7 of the 15 participating states. The predominant serotype O:3 (n = 79 of 106) was distributed in five states (n = 5 of 7). Serotype O:5 (n = 27 of 106) was also found in five states (n = 5 of 7). All isolates contained the virulence plasmid and expressed virulence-associated phenotypic characteristics. These results indicate that swine in the United Stares harbor Y. enterocolitica that can potentially cause human illness.