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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Food and Feed Safety Research » Research » Publications at this Location » Publication #306811
Title: Perspectives on super-shedding of Escherichia coli O157:H7 by cattle

Author
item MUNNS, K - Agriculture And Agri-Food Canada
item SELINGER, B - University Of Lethbridge
item STANFORD, K - Alberta Agriculture And Rural Development
item GUAN, L - University Of Alberta
item Callaway, Todd
item MCALLISTER, T - Agriculture And Agri-Food Canada

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2014
Publication Date: 2/2/2015
Publication URL: http://handle.nal.usda.gov/10113/60555
Citation: Munns, K., Selinger, B., Stanford, K., Guan, L., Callaway, T.R., Mcallister, T. 2015. Perspectives on super-shedding of Escherichia coli O157:H7 by cattle. Foodborne Pathogens and Disease. 12:89-103.

Interpretive Summary: The term “supershedder” has been applied to cattle that shed concentrations of E. coli O157:H7 in amounts greater than 104 colony forming units per gram of feces. Supershedders have been reported to have a substantial impact on the prevalence and transmission of E. coli O157:H7 in the environment. The specific factors responsible for supershedding are unknown, but roles played by characteristics of the bacterium, animal host, and environment are discussed. The impact of identification of supershedders could provide specific targeting strategies such as bacteriophage therapy, probiotics, vaccination, or dietary inclusion of plant secondary compounds. Evidence that supershedder isolates share a commonalty with isolates linked to human illness makes it imperative that the etiology of this phenomenon be characterized.

Technical Abstract: Escherichia coli O157:H7 is a foodborne pathogen that causes illness in humans worldwide. Cattle are the primary reservoir of this bacterium with the concentration and frequency of E. coli O157:H7 shedding varying greatly among individuals. The term “supershedder” has been applied to cattle that shed concentrations of E. coli O157:H7 >104 CFU/g feces. Super-shedders have been reported to have a substantial impact on the prevalence and transmission of E. coli O157:H7 in the environment. The specific factors responsible for supershedding are unknown, but are presumably mediated by characteristics of the bacterium, animal host, and environment. Super-shedding is sporadic and inconsistent, suggesting that biofilms of E. coli O157:H7 colonizing the intestinal epithelium of cattle are intermittently released into feces. Phenotypic and genotypic differences have been noted in E. coli O157:H7 recovered from super-shedders as compared to low-shedding cattle, including differences in phage type (PT21/28) carbon utilization, degree of clonal relatedness, tir polymorphisms, and differences in the presence of stx2a and stx2c, as well as antiterminator Q gene alleles. There is also some evidence to support that the native fecal microbiome is distinct between super-shedders and low shedders and that low-shedders have higher levels of lytic phage within feces. Consequently, conditions within the host may determine if E. coli O157:H7 can proliferate sufficiently for the host to obtain super-shedding status. Targeting super-shedders for mitigation of E. coli O157:H7 has been proposed as a means of reducing the incidence and spread of this pathogen to the environment. If super-shedders could be easily identified, strategies such as bacteriophage therapy, probiotics, vaccination, or dietary inclusion of plant secondary compounds could be specifically targeted at this subpopulation. Evidence that super-shedder isolates share a commonalty with isolates linked to human illness, makes it imperative that the etiology of this phenomenon be characterized.