**CSREES**

**Post-Award Management Workshop for Non-competitive Food Safety
Grants**

**August 22-24, 2005 Waterfront Centre, Room 1410**

**800 9^th^ St. SW Washington, DC 20024**

**[ABSTRACTS]{.underline}**

**Behavior of *Enterobacter sakazakii* and Parasites in Ready-to-Eat
Foods: Survival, Growth, and Decontamination**

Larry R. Beuchat and Ynes R. Ortega

Center for Food Safety

University of Georgia

Contact: <lbeuchat@uga.edu>

*Enterobacter sakazakii* has been isolated from numerous environmental
samples taken from food processing plants, hospitals, and homes as well
as from a wide range of ready-to-eat (RTE) foods and food ingredients.
Survival and growth characteristics of *E. sakazakii* in reconstituted
infant formula has been studied but the behavior of the pathogen in
reconstituted infant cereal and on fruits and vegetables is unknown.
Unpasteurized fruit juice and fresh fruits and vegetables have been
implicated as sources of *Cryptosporidium parvum* and *Cyclospora
cayetanensis* infections. Another parasite, *Encephalitozoon
intestinalis*, is also known to cause human infections. The
effectiveness of sanitizers in killing *E. sakazakii* and parasites on
fresh produce has been given only meager research attention. The major
objectives of a study to be initiated September 1, 2005 are to (1)
determine the performance of differential, selective media to recover
injured cells of *E. sakazakii* from RTE foods; (2) determine survival
and growth characteristics of *E. sakazakii* in infant cereal containing
various grain and fruit components and in fresh fruit and vegetable
juice; and (3) determine the effectiveness of sanitizers in killing *E.
sakazakii*, *C. parvum, C. cayetanensis*, and *E. intestinalis* on fresh
fruits and vegetables. Knowledge gained from this research will serve as
a base for developing strategies, interventions, and recommendations to
control or eliminate *E. sakazakii* and parasites in two distinctly
different groups of RTE foods.

**International Center for Food Industry Excellence**

Mindy Brashears

Texas Tech University

Contact: <mindy.brashears@ttu.edu>

The International Center for Food Industry Excellence is a collaborative
effort between the College of Agricultural Sciences and Natural
Resources and the College of Human Sciences. Twelve faculty member focus
research and outreach efforts in the areas of food safety, value added
processing, nutrition and education. Highlights of our programs
include: 1) Pre-harvest interventions for beef feedlot cattle to reduce
*E. coli* O157 prior to slaughter were developed; 2) Post-harvest
interventions on cattle hides and beef trim have been successful in
reducing both *Salmonella* and *E. coli* O157 in the product to ensure
the safety of the food supply; 3) Evaluation of factors resulting in the
emergence of antibiotic resistant drugs in the food supply; 4)
Development of standards for USDA guidelines to identify age of cattle
at slaughter using detention; 5) A nutritionally enhanced sausage
product was developed for the school lunch program; 6) Development of
better methods of food delivery in nursing homes; 7) Determination of
the potential for using cottonseed oil for frying; 8) Development of
consumer and industry information bulletins; and 9) Delivery of multiple
workshops including HACCP, Advanced HACCP, Recalls, Sanitation, Beef
Baccalaureate, and Poultry 101.

The Center has a 15 member industry advisory board that directs them in
making research and outreach decisions. Further information about the
center as well as consumer outreach bulletins can be accessed at our
website at [www.icfie.asft.ttu.edu](http://www.icfie.asft.ttu.edu/).

**Food Safety Consortium**

Michael Johnson, James Dickson and Curtis Kastner

University of Arkansas, Iowa State University, Kansas State University

Contact: <mjohnson@uark.edu>

The Food Safety Consortium (FSC) was organized in 1988 with cooperation
among the states of Arkansas, Iowa and Kansas to focus on food safety
issues concerning the production and use of poultry, pork and beef
products, respectively. The original congressional mandated areas were
intervention points to control microbial and chemical hazards, rapid
detection and identification of agents and toxins, risk monitoring and
health risks to which were added risk assessment for hazard reduction
and control, developing technology to reduce hazards and improve animal
food product quality and develop, complement and maintain technology
transfer systems to communicate the work of the FSC. The FSC has been
effective in leveraging the funds provided by CSREES with competitive
federal, industrial/commodity research funds and state matches that gave
total aggregate funds that were 8.6 and 8.1 times the amounts provided
by CSREES for FY 2003 and 2004 cycles. Strategies for reductions in and
control of enterohemorrhagic ***E*. coli*, Salmonella, Campylobacter***
and ***Listeria*** are major focuses of research. FSC funded researchers
have averaged 50-100 refereed papers/year over the period of1999-2004.
The research teams of the cooperating schools are positioned to take the
lead in Homeland Security issues involving food safety and security.

**Institute of Food Science and Engineering**

University of Arkansas

Michael Johnson

Contact: <mjohnson@uark.edu>

The Institute of Food Science and Engineering (IFSE) provides a
mechanism for the University of Arkansas, Division of Agriculture to
utilize its multidisciplinary expertise to develop and disseminate
scientific information to address demand-driven research problems
critical to enhancing the food supply. The Institute is composed of
three interrelated Centers: the Center for Food Processing and
Engineering, the Center for Food Safety and Quality, and the Center for
Human Nutrition that serve to soften disciplinary lines to facilitate
cooperation and team building among research and extension faculty. IFSE
scientists have received almost \$5.5 million in industry support
through partnerships with 128 food industries in 34 states and 7
countries. Current research efforts are aimed at enhancing production
and processing techniques, assuring food safety, utilizing by-products
of food processing, improving the sensory and nutritional quality of
food and meeting the nutritional requirements and food preferences of a
changing society. Research program areas include: Rice Processing;
Vineyard Mechanization and Enology; Pickle Science and Technology;
Sensory and Consumer Sciences; and Functional Foods. IFSE scientists
have published over 260 articles in scientific journals as well as 13
fact sheets/monographs. IFSE outreach activities include workshops that
provide educational opportunities to Extension faculty, entrepreneurs,
and food industry personnel.

**Food Safety: Farm to Table**

Food and Agricultural Products Center,

Oklahoma State University

Stanley E. Gilliland

Contact: <seg@okstate.edu>

The long-term objectives of this research program are to develop
approaches or methods to help assure the microbial safety of the food
supply from the farm to the table. We will evaluate livestock trailers
as sources of *Escherichia coli* O157:H7 in cattle being transported
from feed lots. Part of the project will focus on control of
*Salmonella* and *E. coli* O157:H7 in the production of swine and
cattle. In this part of the project we will test the influence of
*Lactobacillus acidophilus* on immune responses in swine and cattle.
Biosensors will be developed using molecularly imprinted polymers
specific for *E. coli* O157:H7. These sensors will be evaluated for
efficacy in detecting *E. coli* O157:H7 in foods. The project also will
include the development of improved methods for detecting *Listeria*
*monocytogenes*. Microarrays will be used to type strains of *Listeria
monocytogenes* to see if relationships to virulence can be detected.
Diagnostic tools will be developed to trace *Staphylococcus aureus* or
its toxin back to the source. Two varieties or oregano and/or fractions
thereof will be compared for inhibitory action toward food borne
pathogens in refrigerated foods. Another objective will focus on
development of a method to remove (or inactivate) abnormal prions from
animal by-products.

**Microbiological Safety of Composting Process as Animal Manure
Treatment**

M.P. Doyle, X. Jiang, M.C. Erickson, G. Boyhan, D.M. Granberry, and G.
Zehnder

University of Georgia

Contact: <mdoyle@uga.edu>

This research was initiated to develop practical composting practices
that could be easily adopted by small farmers to produce compost of
acceptable quality from animal manure that would be virtually free of
viable human pathogens. To provide base line information on the
prevalence of human pathogens in compost with current practices, samples
were taken at several time points over a 6-month period from compost
piles on several poultry farms. Both presumptive *Listeria* and
presumptive *Salmonella* were found in these samples. As the majority of
the positive samples were found in surface samples where temperatures
were significantly lower than interior portions, controlled studies are
being designed to investigate time-temperature conditions for pathogen
inactivation at temperatures found on the surface of compost piles. Two
15-L bioreactors have been built to conduct the composting under
well-controlled conditions. In addition, four strains of *Salmonella*
and five strains of *Listeria monocytogenes* have been labeled with the
jellyfish green fluorescent protein (gfp) that facilitates enumeration
of these isolates from the compost. To date, several composting trials
have been conducted with *Salmonella*-contaminated composts. In the
presence of 0.08% ammonium sulfate, temperatures in the compost
increased sooner than in the absence of this ingredient and coincided
with increased pathogen inactivation in the "bottom-center" location of
the bioreactor. A wide range of conditions was encountered to achieve
pathogen inactivation with final pH ranging from 5.8 to 8.7 and
cumulative heat exposure ranging from 2.8 to 39.3 day-degrees (\>40°C).
Bioreactor studies are continuing in order to explore the source for
variability in these inactivation conditions.

**Food Safety Risk Assessment at NDSU -- Finding Links**

Catherine M. Logue (PI)^a^, Lisa K. Nolan ^b^, Verlin Hinsz ^a^, William
Nganje ^a^, Tim Sellnow ^a^, and Margaret Khaitsa ^a^

^a^The Great Plains Institute of Food Safety, North Dakota State
University

^b^Iowa State University

Contact: <Catherine.logue@ndsu.nodak.edu>

Annually, foodborne illness accounts for approximately 76 million cases
and 5,000 associated deaths. As part of our food safety initiative at
NDSU faculty from the Great Plains Institute of Food Safety have
developed a multi-disciplinary research program involved in assessing
the risk of human illness associated with *Salmonella* contamination in
poultry. Our research team consists of a meat microbiologist, a
veterinary bacteriologist, an agricultural economist, an epidemiologist,
a communications expert and an organizational psychologist. Our research
has highlighted how *Salmonella* contamination occurs during processing
and has developed methods for sampling and molecular analysis of
recovered isolates. Other aspects of our research program have focused
efforts on approaches to reducing risk, and investigating cost effective
mitigation strategies. In addition, we have examined the epidemiology of
*Salmonella* in relation to human illness and the role of psychology and
motivation in enhancing food safety. Our communications experts have
investigated the role of communication in high reliability
organizations; developed best practices models and are currently testing
messages for effectively communicating food safety crises. Our current
work is continually evolving and developing new methods and means for
assessing risk. Our data will have application for other researchers
also studying and developing risk models.

**Cadmium Content in Pacific Northwest Oysters**

Aimee Christy^1^, Dan Cheney^1^, and Michael Morrissey^2^

^1^Pacific Shellfish Institute, WA and ^2^Oregon State University

Contact: <Michael.morrissey@oregonstate.edu>

There is increased concern about the health effects of cadmium in
shellfish, especially oysters. There are efforts to lower the maximum
limit (ML) for cadmium in molluscan shellfish to 1 µg/g in an effort to
protect consumers from long-term exposure of the metal. This study
evaluates the spatial distribution of cadmium in Pacific oysters
(*Crassostrea gigas)* harvested from 34 commercial, recreational and
tribal shellfish growing areas located throughout the states of
Washington and Oregon and attempts to identify the factors and
mechanisms that influence these concentrations. Findings indicate that a
weak spatial trend in oyster cadmium concentration exists with levels
increasing in a northward and seaward direction with the exception of
consistently elevated levels along the greater length of Hood Canal.
Cadmium concentrations from 92 oyster composites ranged from .44-2.5
µg/g with a WA state-wide average of 1.24 µg/g and OR average of 1.32
µg/g. Fifty-six percent of oyster composites exceeded CODEX's proposed 1
µg/g ML for cadmium in molluscan shellfish and 17% exceeded Hong Kong's
2 µg/g import standard. Tissue cadmium concentrations do not appear to
be directly related to the amount of cadmium in seawater or sediments.
Instead, cadmium levels seem to be more influenced by oyster tissue
weights, growth rates and factors that increase the rate of cadmium
uptake such as high temperature and low salinity waters.

**Advancing the Implementation of Post-Harvest Treatments for Safer Raw
Oyster Products**

Steven Otwell

Food Science & Human Nutrition Department

Aquatic Food Products Program

University of Florida

Contact: <Otwell@mail.ifas.ufl.edu>

USDA's Special Food Safety Grants were initiated in Florida in response
to historical mandates and public expectations for safer oyster
products. The anticipated changes were deemed necessary to reduce
recurrent illnesses resulting from consumption of the raw half-shelled
products of these traditional molluscan shellfish. Oyster related
illnesses, specifically from *Vibrio vulnificus* remains the number one
seafood safety issue the United States. Mandates for change involve all
molluscan shellfish commerce through traditional harvests, aquaculture
and imports. These USDA grants have provided a combined research and
extension response based at the University of Florida to address
implementation of the most appropriate post-harvest treatments (PHT's)
designed to reduce *Vibrio vulnificus*. In combination with the regional
and pertinent trade associations, the involved regulatory agencies and
other academic expertise, this effort has 1) screened various PHT
options applicable in Florida and other regions along the Gulf of
Mexico; 2) installed a unique commercial ultra-low freezing operation
that significantly reduces *V. vulnificus* in raw products; 3) developed
new microbial real time-PCR methodology for use in PHT validations and
verifications to comply with regulatory guidelines; and 4) opened and
staffed an historically unique 'Oyster Industry Lab ' to monitor
commercial performance and maintain an innovative product
'certification' program; while 5) evaluating processing methods to
protect product quality essential to market success; and 6) conducting
economic impact assessments to serve in future planning for commercial
and community adjustments imposed by the PHT mandates.

**Seafood and Aquaculture Food Safety**

Douglas Marshall and Linda S. Andrews

Department of Food Science, Nutrition & Health Promotion

Mississippi State University

Contact: <microman@ra.msstate.edu>

Aquaculture is the farm cultivation of aquatic species including food
fish and shellfish. Aquacultured seafoods have been around for \>4,000
years. In the U.S., 30% of seafood is aquacultured, of which 70% is farm
raised channel catfish. Mississippi alone produces 60% of the U.S.
catfish supply. Collectively seafoods (catfish, shrimp, and oysters) are
the second leading food commodity produced in Mississippi after poultry
production. Seafoods historically have been a leading cause of foodborne
outbreaks in the U.S., although the number of cases is low. A major
focus of this project is to develop biological, chemical, and physical
methods to control pathogens in seafoods, with two secondary efforts on
developing rapid detection methods and on gaining a better understanding
of the nature of pathogens in seafoods. Among many completed projects,
results from the following studies will be highlighted: validation of
DNA probes for *Vibrio parahaemolyticus* and *Vibrio vulnificus*
enumeration, understanding the seasonality of *V. parahaemolyticus* and
*V. vulnificus* in oysters, use of *V. vulnificus* phage as a protective
biocontrol agent to prevent infections, determining the irradiation
sensitivity of *V.* *vulnificus* in oyster shellstock, and assessing the
potential of ready-to-eat shrimp as a vehicle for transmission of
antibiotic resistant pathogens.

**Seafood Safety Research in Alaska**

Brian Himelbloom

University of Alaska, Fairbanks

Contact: <bffbhh@uaf.edu>

Our focus addresses the aspects of listeria contamination and its
inhibition in raw materials to finished products for assisting the
Alaska smoked seafood industry. A survey of several plants showed some
presence of *Listeria monocytogenes* and *L. innocua* in environmental
sampling. Most of the locations were drains which could serve as
reservoirs for recontamination of product lines. As a control step for
raw materials, calcium oxide was found useful for reducing listeria
contamination of whole salmon. The inhibition was attributed to the high
pH of the holding solution. A post-brining step which incorporated
liquid smoke and acetic acid was inhibitory to listeria. For cold smoke
operations, this combined treatment is an alternative to wood smoke. A
current project involves the role of the brined, dried fish tissue as a
barrier to listeria and staphylococci inactivation during hot-smoking of
salmon. Preliminary results show smoke needs to be added initially for
maximum inhibition to occur. Antilisterial carnobacteria were isolated
from raw salmon and tested for bacteriocin production. The peptide and
the competitive growth of the probiotic may be useful in inhibiting
listeria contamination of smoked fish products. Continued efforts in
these research areas will help smoked seafood processors provide safer
products.

Seafood Safety Program

University of Massachusetts, Amherst

Robert Levin

Contact:
[**relevin@foodsci.umass.edu**](mailto:relevin@foodsci.umass.edu)

The principle goals of our Seafood Safety program are to develop various
aspects of technology to enhance the safety of seafood and to enhance
the efficacy of Seafood based by-products. The specific technologies
being developed and underway to achieve these goals consist of: (1)
real-time PCR methodology for rapid quantitation of live as
distinguished from dead human pathogenic bacteria on seafood tissue, (2)
determination of the ability of *Listeria monocytogenes* to grow within
protozoa and evaluate the sensitivity of this pathogen to sanitizers
during intracellular protozoan growth, (3) assessing the most effective
methodology for destroying bacterial biomass in floor drains of seafood
processing plants which can serve as continual loci of contamination by
*L. monocytogenes*, (4) assessing the risk derived from the occurrence
of spore forming toxin producing bacteria on seafood, (5) assessing the
effectiveness of newly developed phytochemical antimicrobial agents for
enhancing the safety of seafoods, (6) enhancing the control of
pathogenic bacteria on seafood and extending refrigerated storage life
of seafood by applying micelles and liposomes containing antimicrobials,
(7) determining the effect of specific omega-3 fatty acids derived from
fish tissue on cholesterol metabolism, (8) assessing and optimizing the
stability of liposomes laden with omega-3 fatty acids for incorporation
into a wide variety of food products, and (9) reducing the oxidizability
of membrane lipids of extracted fish proteins.

**Incidence and Control of Histamine Poisoning in Scombroid Fish
Species**

George Flick, David Green, and Thomas Rippen

Virginia Tech

Contact: <flickg@vt.edu>

Histamine poisoning is one of the most common chemically induced seafood
borne illnesses reported in the United States today. Generally it is
believed that the causative agents are biogenic amines (histamine,
putrescine and cadaverine) produced by Gram negative bacteria. Under the
U.S. Food and Drug Administration's HACCP program, growth of
histamine-producing bacteria in potentially hazardous fish is controlled
primarily by limiting the time and temperature conditions. The purpose
of this study was to determine if current regulatory guidelines are
being meet for the control of histamine production in mid-Atlantic
harvested mahi-mahi and yellowfin tuna, and if not, what potential food
safety risks may likely occur.

Twenty-nine composite fish muscle samples were obtained from 18
mahi-mahi and 11 yellowfin tuna troll-caught and analyzed for their
histamine content. No sample analyzed exceeded 2ppm histamine, the
detection threshold for Neogen's ELISA-based Veratox® rapid test. Fish
internal temperatures were continuously monitored from point of harvest
through primary processing to determine individual fish cooling rates.
Mahi-mahi were chilled on ice within 12 hrs of harvest as required under
the federal HACCP guidelines. Generally, yellowfin tuna (60%) did not
meet the HACCP requirement \[uneviscerated tunas exceeding 20 lbs (9.1
Kg) in weight\] of achieving an internal temperature of ≤ 50^o^F
(10^o^C) in 6 hrs.

**Development of a Foodborne Pathogen Subtype Database to Understand and
Reduce Foodborne Pathogen Transmission**

Martin Wiedmann

Department of Food Science

Cornell University

Contact: <mw16@cornell.edu>

To track and control sources of foodborne pathogens, agricultural and
food industries have a critical need for access to advanced molecular
subtyping tools and data. Genomics-based tools and molecular subtyping
methods are already increasingly used for foodborne disease surveillance
and outbreak detection. The Centers for Disease Control and Prevention
(CDC) have developed a National Molecular Subtyping Network for
Foodborne Disease Surveillance (PulseNet), which permits rapid
comparison of bacterial genetic fingerprint patterns. While this
database is available to public health laboratories around the country,
it cannot be easily accessed by industry or academic researchers. In
order to assure broad access the molecular subtyping data for foodborne
pathogens we have developed a comprehensive WWW-based bacterial pathogen
subtype and source database (PathogenTracker;
[www.pathogentracker.net](http://www.pathogentracker.net/)), which
facilitates rapid detection of foodborne disease outbreaks, tracking of
pathogen transmission throughout the food system, and scientific
definition of pathogen subtypes that differ in transmission and
virulence characteristics. Distribution of isolates included in this
database provides a critical resource for foodborne pathogen research
efforts at various institutions. This presentation will provide an
overview of this database and its applications, including associated
activities focusing on the development of improved DNA-sequencing-based
molecular subtyping methods for different foodborne pathogens.

### Improving Food Safety through the Development of Electronic Biosensors

Larry Branen, Greg Bohach, Gary Maki and Wusi Maki

College of Agricultural and Life Sciences and Center for Advanced
Microelectronic and Biomolecular Research (CAMBR)

### University of Idaho

Contact: <lbranen@uidaho.edu>

The University of Idaho has built a strong multidisciplinary group of
molecular biologists, electronic designers, chemists, microbiologists
and food scientists focusing on the development of electronic biosensors
for food safety. USDA support has helped catalyze a new research
institute at the University of Idaho, the Center for Advanced
Microelectronic and Biomolecular Research (CAMBR) which has a major
focus on the development of electronic biosensors. CAMBR and the project
researchers are located in newly built and equipped facilities at an
off-campus UI Research Park which facilitates strong interaction with
industry.

CAMBR's work focuses on the development of electronic biosensors that
can quickly detect the presence of microbial pathogens in foods and food
products. The goal is to produce a biosensor that is highly sensitive,
easy and inexpensive to use and manufacture and provides near real-time
diagnosis. Current detection technology, which centers around gene
amplification and cell culture procedures, has limitations in terms of
false positives or long detection times. A major goal of the research is
to create an intelligent (programmable) electronic detector that is
sensitive and fast and has a wide range of applications.

A biosensor system has been designed consisting of a capture and
amplification system followed by analysis with transistor/detectors,
digitizing electronics and a microprocessor. A biochemical system has
been developed to capture target protein, DNA or other biomolecules from
microorganisms enabling the one step purification and concentration of
the target molecule. Subsequently, signal molecules are generated as a
result of the interaction between a biochemically designed signal probe
and the target molecule that serves to amplify the signal in a process
referred to as bionanotransduction. Bionanotransduction uncouples
biological recognition from signal detection thus allowing parallel
optimization of components and an immediate link with application of new
biosensors. The electronic detection system consists of a metallic
electrode with the surface modified with probe molecules that capture
the signal molecules through specific molecular recognition. A redox
active enzyme can be used to enhance the signal on the electrode and the
current (amperometry) of the electrode is recorded and compared to the
background current of the electrode in absence of the labeled
nano-signal. Direct detection of the RNA nano-signal is also achieved by
use of a field effect transistor based on detection of the intrinsic
charge of the RNA nano-signal resulting in a change in transistor drain
current. The electronic signals in both cases are transferred to a set
of sense amplifiers that in turn are run by a microprocessor. The
microprocessor allows the sensor to have intelligence to interface with
the external world, provide data analysis, insure reliable operation and
allow real-time external control through dynamic programming.

Positive impacts resulting from this project include 1) maintenance of
consumer confidence in the nation's agricultural and food industry; 2)
improved public health; 3) enhanced safety and security of the food
supply; and 4) minimization of the economic destabilization and social
unrest that could result from large scale contamination of the food
supply. The program can also lead to significant economic development
through development of industries that manufacture the electronic
biosensors.

**Intelligent Quality Sensors for Food Safety**

Suranjan Panigrahi, Douglas Freeman, Catherine Logue, Marten Marchello,
Sam Chang, Jake Glower, Chunfeng Huang, Qun Huo

North Dakota State University

Contact: <s.panagrahi@ndsu.nodak.edu>

Multidisciplinary research projects have been initiated to develop
intelligent sensors to characterize spoilage and contamination (with
*Salmonella*) in packaged beef (meat). With a long term goal to develop
miniaturized portable sensors, we plan to characterize food samples by
sensing the gaseous metabolites of bacteria and pathogens in the food
sample. Our research focus is to develop artificial olfactory sensing
system/sensors that would sense the gaseous metabolites. We are using
multiple sensing techniques and have developed modular systems.
Electronic nose (E-nose) modules (based on metal-oxide detectors and its
variations) have been developed and tested. A commercial E-nose system
(Cyranose^TM^ ) based on conducting polymer detector was also used as
only for signal acquisition purposes. All these E-nose systems have been
tested for their performance in classifying spoiled and contaminated
(with Salmonella) meat samples. The obtained results for both spoilage
and contamination experiments show high accuracies. Our research also
focuses on developing pattern recognition techniques using different
statistical and artificial intelligent techniques. Our parallel effort
in IR-based sensing and porphyrin-based sensor material also show
potential for improved selectivity and/or selectivity. We are also using
E-nose systems for characterization of grain for mold growth and soy
milk for natural toxicants.

**Ecology of *E. coli* O157:H7 in Beef Cow-Calf Operations From Ranch to
Feedlot**

Nagaraja, T. G., Richard Oberst, Mike Sanderson, and Ludek Zurek

Department of Diagnostic Medicine/Pathobiology, College of Veterinary
Medicine

Kansas State University

Contact: <tnagaraj@vet.k-state.edu>

*Escherichia coli* O157 is a major food borne pathogen. Cattle are the
primary reservoir and food products contaminated with cattle feces are a
major source of *E. coli* O157. The long term goal of our research is to
identify means to control *E. coli* O157 at the farm level. The
objectives of our continuing research are to develop and validate
improved methods for the detection of *E. coli* O157, to improve our
understanding of the ecology of *E. coli* O157 in cattle operations, and
to identify and test on-farm intervention strategies for control. Our
research has resulted in the following observations and conclusions: 1.
Hindgut of cattle was the major site of prevalence. 2. Swabbing the
rectoanal junction was a more sensitive method than fecal sampling for
determining prevalence of *E. coli* O157 in cattle. 3. Monenisn, a
widely used feed additive, does not prolong the duration of shedding. 4.
Feeds in feed bunks and house flies collected from feedlot pens were
positive for *E. coli* O157, suggesting both as potential vehicles for
dissemination of the organism in animals, and flies could possibly be
source of infection for humans. We have analyzed genomic fingerprints of
isolates by PFGE to compare clonal similarities of isolates to determine
association and distribution.