Progress 02/01/15 to 01/31/18
Target Audience:academic professionals, research scientists, public health authorities Changes/Problems:
What opportunities for training and professional development has the project provided?The project allowed for the training of undergraduate and graduate students in microbial food safety. How have the results been disseminated to communities of interest?As journal article and national meeting of food safety professionals. What do you plan to do during the next reporting period to accomplish the goals?
What was accomplished under these goals?
The goal was to determine the presence of the Clostridium perfringens epsilon toxin gene (etx) in isolates from retail meat, poultry, spices, processed and, to a lesser extent,pet foods. The procedure involved the enumeration, isolation, and confirmation of this organism using FDA standard methods of analysis. Once confirmed as C. perfringens, isolates were assessed for the presence of etx and for the presence of the enterotoxin gene (cpe) as well, using the Polymerase Chain Reaction (PCR). 431 retail samples of fresh meat and poultry, 247 spice samples, 193 processed meat samples, and 32 pet food samples were examined for the presence and levels of C. perfringens. Generic C. perfringens was present in 43 (17%) of the spice samples, 79 (18%) of the meat and poultry samples, 4% of the processed meat and 9% of pet food samples. In total, levels of viable C. perfringensranged from 3.6 to 2400/gm from all samples. In the case of the epsilon toxin gene (etx): Four of the spice and four of the meat and poultry isolates possessed the epsilon toxin gene (etx) equivalent to their presence in approximately 1-2% of C. perfringens isolates from these sources. No epsilon toxin genes were detected in C. perfringens isolated from processed and pet foods. We conclude that, like enterotoxin-positive C. perfringens (see below),the presence of epsilon toxin-positive C. perfringens is present in retail meat, poultry, and spices at verylow levels. Using a commercial epsilon toxin assay, 5 ofthe 8 epsilon toxin gene-positive isolates produced the toxin itself in culture fluids. It is not clear why the epsilon toxin gene, though present, was not expressed in 3 of the isolates. As the gene for the epsilon toxin is carried on a plasmid, the differentlevelsof epsilon toxin in culture fluids of isolates may be a reflection ofplasmid copy number. Although the role of the epsilon toxin in animal diseases has been well established, previous, though limited, surveys of its presence in isolates from retail food has found it to be absent or rare. Our results support the conclusion that it is unlikelythatepsilon-toxin producing C. perfringens would be commonly encounteredin retail foods (perhaps in 1-2% of isolates), even though the organism is readily isolated from retailprotein foods. In the case of the enterotoxin gene (cpe): cpe was detected in: none of the meat and poultry isolates, 4% of the processed and pet food isolates and 17% of the spice isolates. Past surveys have detected enterotoxin-positive C. perfringens at level of approximately 5 or less percent of C. perfringens isolates from retail foods.
Lee, C.-A. and Labbe, R. 2018. Distribution of enterotoxin- and epsilon-positive Clostridium perfringens in U.S. retail spices. Journal of Food Protection 81:394-399.