CAFPA Fall Meeting on non-O157 STEC
On September 15th 2009, CAFPA held its annual meeting in Washington, DC. The topic was non-O157 Shiga toxin-producing E. coli (STEC). There were four speakers. Dr. Angela Melton-Celsa of the Uniformed Services University of Health Sciences gave an overview of STEC. She discussed the pathogenesis of these organisms and associated virulence factors. Shiga toxin (types 1 and 2) and the attaching and effacing gene (eae) are two major virulence factors associated with STEC. Some STEC lack the LEE locus which carries the eae gene and have alternative virulence factors, such as toxins and adhesins. She also discussed some of her research with STEC strains harboring Stx2 activatable in mice.
Dr. Hannah Gould of the Centers for Disease Control and Prevention (CDC) gave an update on the epidemiology of STEC in the United States. FoodNet data on infection information of E. coli O157 versus non-O157 STEC were discussed. Factors such as age, gender, and seasonality of O157 and non-O157 STEC infections were similar. Non-O157 STEC infections are more sporadic than infections of O157 and are correlated with fewer outbreaks. E. coli O157 has a much higher incidence of hemolytic uremic syndrome (HUS) (6.3% O157 vs. 1.7% non-O157), hospitalizations (42% O157 vs. 12% non-O157), and deaths (0.6% O157 vs. 0.1% non-O157). Another interesting difference seen between infections due to O157 and non-O157 STEC was the incidence of international travel was five times greater for patients with non-O157 STEC infection. Gould reported that there have been 22 outbreaks involving non-O157 STEC since 1990, with 83% of these being foodborne. Some of these outbreaks are attributed to other pathogens including norovirus, Cryptosporidium, and Vibrio spp. Implicated foods included juice, cider, berries, cheese, and leafy greens.
The next speaker was Dr. Pina Fratamico of the United States Department of Agriculture (USDA), Agricultural Research Service (ARS) who discussed detection and identification methods for non-O157 STEC. The great diversity in virulence profiles within strains of non-O157 STEC presents a challenge in developing testing methods. She discussed her research in testing different cultural methods, kits, and diagnostic systems for detection and identification of non-O157 STEC. Fratamico also described a strategy for detection of non-O157 STEC in beef using PCR and immunomagnetic separation and plating.
The final speaker was Jolyda (Jody) Swaim of Olsson, Frank, Weeda, Terman, Bode, Matz, PC. She presented a regulatory perspective on non-O157 STEC. The methods currently available for non-O157 STEC are laborious research methods that would not be practical for industry use. Swaim noted that the current interventions in place for other pathogens such as Salmonella and E. coli O157 seem to work for non-O157 STEC based on multiple studies. Products currently tested for E. coli O157, such as ground beef, are likely to also be tested for non-O157 STEC if some of these organisms become adulterants. She believes additional research is needed to determine their status.
The presentations were followed by a CAFPA business meeting. Revisions to the CAFPA constitution and bylaws were discussed and voted on by members. CAFPA was able to add 22 new members at the meeting.