Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/23/2010
Publication Date: N/A
Technical Abstract: Introduction: Swine are the only known animal reservoir of Yersinia enterocolitica (YE), a human pathogen. Since YE is a fecal organism of swine, the primary goal of this study was to evaluate the prevalence, serotype, virulence plasmid (pYV)-associated characteristics, clonality, and antibiotic susceptibility of YE from swine feces. Methods: A total of 2,793 swine fecal samples were tested for the presence of YE in pigs from 78 production sites in 15 pork producing eastern and mid-western states in the United States, September 2000 to March 2001. YE were detected using a combination of ITC enrichment and CIN agar, and identified by fluorogenic 5' nuclease PCR using chromosomal attachment-invasive ail gene. Serotyping was done with commercial reagents. Isolates were tested for markers of virulence including carriage of a 70 kbp plasmid, colony morphology, low calcium response, Congo red uptake, crystal violet binding, autoagglutination, hydrophobicity, and presence of a cytotoxicity factor, YopE. The clonal distribution was determined by digestion with Xbal and subsequent pulsed field gel electrophoresis. The antimicrobial susceptibility was evaluated by agar disk diffusion to 16 antibiotics. Results: The mean prevalence of YE was 13.10% (366 out of 2,793 tested) and 41 sites (53.25%) out of 77 premises contained at least one sample positive for the ail sequence. The ail-positive isolates (n=106) originated from 7 of the 15 participating states. The predominant serotype O:3 (n=79/106) was distributed in five states. Serotype O:5 (n=27/106) was also found in five states. All isolates contained pYV expressing virulence-associated phenotypes. The clonal distribution of these isolates showed that all O:3 and O:5 isolates were highly clonal within a serotype regardless of the state of origin. All isolates were susceptible to 13 of the 16 tested antimicrobials; resistance was noted to ampicillin, cephalothin, and tetracycline. Conclusions: The presence of ail gene, serotypes, and pYV encoded virulence determinants indicate that these isolates are pathogenic. The results from this study will aid in the design of future epidemiological investigations concerning on-farm prevalence and associated factors for the presence of pathogenic YE. Additionally, the results confirmed that swine are a reservoir for YE.