Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2006
Publication Date: 9/20/2006
Citation: Helgerson, A.F., Sharma, V.K., Dow, A.M., Schroeder, R., Post, K., Cornick, N.A. 2006. Edema disease caused by a clone of Escherichia coli O147. Journal of Clinical Microbiology. 44(9):3074-7. Interpretive Summary: Edema disease is a systemic disease of weaned piglets, caused by host adapted strains of E. coli that produce a variant of Shiga toxin 2, Stx2e. Clinical signs of edema disease include swollen eyelids, neurological symptoms such as ataxia and stumbling, recumbancy and/or sudden death. These E. coli strains colonize the ileum. Many edema disease isolates also produce heat stabile toxins which cause diarrhea. Historically, edema disease has been caused by different groups of E. coli. Evidence suggests that these E. coli strains can be transmitted from both the sow and the environment to the piglets. Once this organism is in the pig’s environment it is difficult to eliminate and can be carried to other areas on the farm or off the farm to other swine herds. Understanding genetic relationships between strains responsible for edema disease outbreaks in pigs is important for identifying genes that could potentially be used as markers for rapid identification of outbreak strains.
Technical Abstract: Edema disease is a systemic disease of weaned pigs caused by host adapted strains of E. coli most commonly belonging to serogroups O138, O139 or O141. Recently, E. coli O147 strains containing the virulence genes f18, sta, stb and stx2e have been recovered from outbreaks of edema disease across the U.S. Pulsed-field gel electrophoresis was used to determine that the majority of these strains (34/43) were closely related to one another. Analysis using multilocus restriction typing confirmed the PFGE data and indicated that the cluster of edema disease strains were only distantly related to other E. coli O147 strains. Serogrouping of edema disease isolates from the Iowa State University Veterinary Diagnostic laboratory indicated that 42% belonged to serogroup O147. Our data suggests that these strains may represent an emerging clone of edema disease-causing E. coli in the U.S.