Prevalence, Persistence, and Transmission of Shiga Toxin-Producing Escherichia Coli

Non-Technical Summary:<br/>
Zoonotic pathogens are associated with countless foodborne disease outbreaks. More specifically, pathogenic E. coli, such as Shiga toxin-producing E. coli (STEC) is a significant human pathogen. It survives in healthy cattle, the reservoir of this pathogen, and threatens food safety, causing economic losses through product recalls and clinical treatments. Although progress has been made in reducing the incidence of diseases caused by foodborne pathogens, they remain of great concern. STEC O157 is an important cause of hemorrhagic colitis, bloody diarrhea and hemolytic uremic syndrome (HUS) in humans. Also, more recently, the "Big 6" non-O157 STEC serotypes (O26, O45, O103, O111, O121, and O145) have been associated with human outbreaks. The Center for Disease Control and Prevention (CDC) has estimated that pathogenic STEC cause ca. 269,000 cases of illnesses (including ca. 3,700 hospitalizations and 30 deaths) in the United States every year. Despite a great deal of research focusing on improving food safety, the outbreaks caused by STEC are continuously arising. The clearance of STEC at the pre-harvest level is one of the most effective ways to prevent foodborne illness caused by this pathogen. However, control of zoonotic pathogens is challenging because multilayers of high risk factors, including environmental, animal, and bacterial factors, exist in agricultural settings. Therefore, innovative research is needed to breakthrough the barriers. Development of rational mitigation strategies at the pre-harvest level requires a comprehensive understanding of when, where, and how STEC are acquired in animals, and how strains transmit among animals and farms. This research will provide a scientific basis of the prevalence, persistence, and transmission of STEC in animals and farms for development of mitigation strategies for STEC in farms.
<P>
Approach:<br/>
In brief, fecal samples will be collected and transported to the laboratory within 4 h of collection, to minimize bacterial growth. The specimens (containing ca. 10 g of feces) will be suspended in mEC broth, and aliquots of serial dilutions (in 0.1% [w/v] peptone broth) will be directly plated (in duplicate) on MacConkey agar and incubated to determine the concentration of viable STEC. To study the factors that affect prevalence and persistence of STEC in animals and farms, identification methods for STEC will conducted by using multiplex PCR. The stx1 and stx2 genes will be amplified to detect STEC.