Molecular Epidemiology of Clostridium Difficile Food Contamination: Links to Human CDI

<p>NON-TECHNICAL SUMMARY: <br/>Phylogenomic analysis of human and food animal strains strongly suggests both close genetic relationships among food animal and human strains and that pig strains are genetic predecessors of human strains. Attempts to confirm direction of movement of strains (food animals to humans or vice versa) will logically examine materials that pass between them. Consumption of beef and pork by humans is relatively common, while the reverse occurs only under rare and exceptional circumstances. Thus, food animal-to-human transmission via foods seems more likely, in both route and direction, than the alternative. The finding of identical genotypes of CD in humans, retail meats, and food animals gives rise to our overarching hypothesis, namely that humans are exposed to CD from intestines of food animals via consumption of retail meats. Our innovative,
multidisciplinary collaboration will unravel interrelationships among factors affecting food safety. It integrates expertise in clostridial biology, academic and public health epidemiology, molecular microbiology, and extension and education. Thus, the proposed work is not simply microbiology, but has a central epidemiologic focus and is integrated. It is fundamental and mission-linked, exploring multiple factors involved in food safety and providing data on which policies can be based. If our hypothesis is supported, probable risk factors will be identified, and a platform will be built for quantitation of these risks. Data analysis will reveal commonalities and differences within and among CD populations recovered from the various sources and contribute to testing of our fundamental hypothesis that CD flows to human populations from food animals, via foods. Thus, the data are amenable
to global surveillance and studies of bacterial population structure. Genetic lineage will aid in understanding CD evolution, particularly with regard to the relationship of food isolates to human disease. Measurable changes in learning and actions will result across the various audiences and stakeholder groups. At completion, we will have identified outreach materials needed to educate target audiences. Outreach programs will provide the diverse industry clientele with information regarding specific measures for intervention. Accomplishments in education will be the nucleation point around which current and future efforts in food safety education will form. Other opportunities will almost certainly arise, particularly as increased interaction in the broad sense leads to synergies among faculty research programs. Furthermore, the substantial number of undergraduates seeking laboratory
research experience will likely expand both our ability to pursue answers to food safety questions and to increase the number of individuals who know and understand food safety principles.
<p>APPROACH: <br/>Specific Aims. Clostridium difficile (CD) infection (CDI) is increasingly common and severe. It has been considered strictly nosocomial, but the incidence of community-associated (CA)-CDI has increased, and may now account for nearly 50 per cent of cases. CA-CDI is epidemiologically different from hospital-associated (HA)-CDI and the source of infection for true CA-CDI is unknown. CDI occurs in food animals, and we recently demonstrated fully-toxigenic CD in greater than 40 per cent of retail meats. Genotypes of food strains include those from food animals, as well as the current epidemic human strain. Thus, there may be a connection encompassing food animals, retail meats, and human populations with CDI. We hypothesize that humans are exposed to CD via consumption of foods of animal origin, and will begin to test this hypothesis through work under the
following specific aims: 1). Obtain and characterize CD isolates from foods of animal origin and from humans with CDI in Arizona. 2). Perform a spatial analysis of CD and CA-CDI. 3). Establish phylogenetic relationships among strains to infer source and route of transmission. 4). Develop extension and education programs on CDI and food safety.
<p>PROGRESS: 2013/02 TO 2014/02<br/>Target Audience: Scientific, medical and veterinary communities Changes/Problems: The implementation of this project was delayed by the transfer of the PI from University of Arizona to Iowa State University and then the retirement of the current PI. We are working through these issues and continue to make progress on the project What opportunities for training and professional development has the project provided? We have provided training to 4 undergraduate students. How have the results been disseminated to communities of interest? The results will be published in peer-reviewed journals, presented at scientific conferences and by talks given to producer groups and food safety professionals. What do you plan to do during the next reporting period to accomplish the goals? We expect to complete the culturing of the food samples and the
human samples. Isolates will be genotyped by ribotyping and MLVA to establish phylogenetic relationships. We will evaluate clustering in space adn time to infer sources and possible transmission routes between hospital and community acquired cases of CDI and food sources.
<p>PROGRESS: 2012/02/29 TO 2013/02/27<br/>Target Audience: Scientific, medical and veterinary communities Changes/Problems: The implementation of this project was delayed by the transfer of the PI from University of Arizona to Iowa State University and then the pending retirement of the current PI. We are working through these issues and continue to make progress on the project. What opportunities for training and professional development has the project provided? We have provided training to 4 undergraduate students How have the results been disseminated to communities of interest? The results will be published in peer-reviewed journals, presented at scientific conferences and by talks given producer groups and food safety professionals. What do you plan to do during the next reporting period to accomplish the goals? We expect to complete the culturing of the food
samples and the human samples. Isolates will be genotyped by ribotyping and MLVA to establish phylogenetic relationships. We will evaluate clustering in space and time to infer sources and possible transmission routes between hospital and community acquired cases of CDI and food sources.
<p>PROGRESS: 2011/03/01 TO 2012/02/28<br/>OUTPUTS: We continue to find Clostridium difficile in foods purchased at retail. This, as well as evidence from other labs, continues to reinforce the conclusion that retail meats (and likely other foods) are a source of C. difficile for colonization of humans. Based upon our knowledge of pathogenesis of C. difficile infection (CDI), it seems likely that clinical disease follows when the bowel microbiota is disrupted by the effects of antimicrobials or proton pump inhibitors. PARTICIPANTS: J Glenn Songer (Iowa State University) served as the PI. He was assisted at Iowa State by technicians Chandra Tangudu and Sharon Rasmussen. Co-Investigators included Kelly Reynolds (food sampling, University of Arizona), Ken Komatsu (human specimens, Arizona Department of Health Services), Jane Marsh (MLST work, University of Pittsburgh), and
Randy Singer (epidemiology, University of Minnesota). In addition, we have afforded opportunities for training to four undergraduate students thus far. TARGET AUDIENCES: If the outcome of the study is to show that C. difficile IS foodborne (as now appears to be the case), the target audience for our findings will be (a) the human medical community and (b) the veterinary and food safety communities, which will have to address the presence and transmission of this organism from animals/retail meats to humans. PROJECT MODIFICATIONS: Not relevant to this project.