IAFP 2002
Session Summaries
At the request of the Dairy, Food and Environmental Sanitation Management Committee,
Members of the Student Professional Development Group were invited to prepare
summaries of sessions they attended at IAFP 2002. Following are the write-ups
the students prepared.
S01
— Antibiotic Resistance
S02 — Viruses in Foods
S03
— Development in Intervention Technologies to Enhance Produce Safety
S04 —
Safety of Latin-Style High Moisture Fresh Cheese
S06
— Minimizing the Risk of Salmonella
Enteritidis in Shell Eggs
S07 — Microbiological
Food Safety at Retail
S08
— Extended Shelf Life Meat Products–Issues and Interventions
S09
— Cooperating to Improve Foodborne Outbreak Investigations
S10
— Integrated Approaches to the Study and Control of Foodborne Pathogens in
Meat and Poultry
S11 — Listeria
Research Update
S12 — Current Issues
in Seafood Safety
S13
— Controlling Clostridium perfringens
Hazards during Cooling
S14
— Innovation in Retail Food Safety Management Systems and Technology
S15
— Alternatives in Dairy Waste Management: Create New Products or Generate
Power!
S16
— Chronic Wasting Disease and Other Transmissible Spongiform Encephalopathies
S17
— Applications of DNA Chip Technology in the Food Safety Area
S18 — Sanitary
Design of Plants and Equipment
S19
— Risk Assessment of Food Workers’ Hygiene Practices and Intervention
Strategies
S20
— Customized Approaches to Microbiological Risk Assessment
S21 — Control
of Escherichia coli O157:H7 in Cattle
S22 — Current Practices
in Produce Safety
S23 — Food Safety Education
Lecture Topics
T01 — Meat and Poultry
Microbiology
T02 — Microbiological Methods
T03 — GMOs and Produce
T04 — Public Health and
Outbreaks
T05 — General Food Microbiology
T06 — Antimicrobials
S01
— Antibiotic Resistance
Michelle Danyluk, University of Georgia and Kelly Felkey, University
of Florida
This session provided an extensive background on antibiotic resistance in relation
to history, persistence, multiple resistance factors, transmission, and removal.
T. O’Brien discussed the history and mechanism of antibiotic resistance. Antibiotic
use began 65 years ago. When antibiotics are utilized at moderate concentrations,
bacteria survive by natural selection. Evolution involves mutations of genes
on chromosomes or plasmids. Such changes may lead to a strain or species with
a selective advantage, such as the ability to resist antibiotics. A. Gupta presented
information on Salmonella Newport resistance and difficulties in obtaining specimens.
Salmonella spp. is part of a surveillance system operated by the Center for
Disease Control and Prevention and the National Antimicrobial Resistance Monitoring
System (NARMS). The system has assisted in monitoring identification of the
ACSSuT resistance pattern and new resistance patterns.
P. J. Fedorka-Cray covered multiple drug resistance in foodborne bacteria,
defining multiple resistance patterns in relation to various pathogens. Multiple
drug resistance was defined as the ability of a bacterium to grow in the presence
of two or more antibiotics. Some pathogens discussed in this regard were S.
Newport, S. Typhimurium DT104, C. jejuni and C. coli.
E. J. Threlfall discussed antibiotic resistance trends in Europe, and their
surveillance system “Enter-Net”, which is similar to NARMS. He detailed the
use of standard methods for surveying antimicrobial resistance in Salmonella
spp. and E. coli. Outbreaks of Campylobacter spp.resistant to quinolones and
macrolides, and globalization of S. Typhimurium DT104 through movement of humans
and animals, were also discussed.
S. F. Kotarski introduced the
topic of cephalosporin safety in animal medicine and discussed
a study that was performed to determine residues of cephalosporin in feces and
urine. Four generations of cephalosporins exist, and ceftiofur has been used
in the US for 14 years to treat cattle diseases. Ceftiofur residues are low
in the intestinal tract and high in the environment, but their levels decline
with time. The transmission of antimicrobial resistance in Salmonella spp. can
be monitored, and possibly controlled, by observing shedding, health management,
farm biosecurity, feed and water, transport, comingling, and other stressors.
H.-D. Emborg presented an opposing
viewpoint and a solution to the antibiotic resistance problem. He proposed complete
removal of antibiotic growth promoters (AGP). AGPs were banned for use in cattle
and pigs in Denmark, which produced worries in producers and slaughterhouse
workers, relating to health, production, and feed use. Pigs and broilers produced
without AGP showed few effects with regard to these issues. In Salmonella
spp., resistance to antimicrobials decreased when broilers and pigs were grown
without AGPs.
S02
— Viruses in Foods
Gabriel Sanglay, Virginia Tech and Angela Hartman, Virginia
Tech
Dr.
Craig Hedberg, of the University of Minnesota, discussed the epidemiology of
Norwalk-like viral gastroenteritis. Norwalk-like viruses (NLVs) have caused
approximately 23 million cases, of which 40% are food related. While the
fecal-oral route is the primary mode of transmission, NLVs can also be
transmitted by person-to-person contact, fomites, or airborne transmission. NLVs
are commonly associated with foods such as produce, oysters, or bakery products.
Although these foods can act as vehicles, it has been found that NLVs do not
replicate in the foods. Currently, there is no effective surveillance for viral
pathogens. To prevent outbreaks, preventive measures such as protecting produce
and shellfish beds from human feces, as well as rapid investigation of outbreaks
to identify sources, must be undertaken. Outbreaks must be investigated rapidly
to identify sources.
Dr. Paul Allwood, of the Minnesota
Department of Health, discussed investigating outbreaks of foodborne viral gastroenteritis.
Outbreak investigation is important in order to identify the source, prevent
transmission of the virus, enhance understanding of agents, assess effectiveness
of existing safeguards, develop more effective safeguards, and prevent the use
of viruses in bioterrorism. The goal of investigating outbreaks is to confirm
that the outbreak occurred, identify the agent or agents involved, identify
the food vehicle, and implement control measures. Outbreaks can be identified
by phone calls to a complaint hotline, surveillance, voluntary reports from
healthcare providers, and reports from public health agenices and establishments.
If an outbreak is identified, an investigation begins. Investigation has 3 phases:
epidemiologic, environmental, and laboratory. If a foodborne viral outbreak
has occurred, then enforcement measures and/or operational recommendations are
needed. These can include discarding ready-to-eat foods, excluding ill workers
for upto 72 hours, handwashing training, vaccination of workers (if Hepatitis
A is implicated), or closing down the facility.
Dr. Steve Monroe, of the Center
for Disease Control and Prevention, discussed CaliciNet as a tool to improve
surveillance of NLVs. CaliciNet is a molecular taxonomy tool that can be used
in surveillance for the familiy of Caliciviridae. The family of Caliciviridae
includes the Vesiviruses, Sapoviruses, Lagoviruses, and Noroviruses (NLVs).
CaliciNet is used to identify caliciviruses because they do not grow in cell
culture and there is a great deal of genetic variation within NLVs. NLVs are
rarely detected and reported because they will be found only if they are specifically
targeted. This tool aids in the molecular epidemiology of NLV outbreaks. Results
using CaliciNet have shown that 197 out of 229 (86%) samples have been positive
for NLV detection using RT-PCR. CaliciNet may also be used to link nucleotide
sequences to epidemiologic information so as to identify and compare calicivirus
strains in “real time.”
Dr. Lee-Ann Jaykus of North Carolina
State University discussed environmental persistence and transfer of NLVs. NLVs
are unique because they are obligate intracellular parasites that do not grow
in food; they are antigenically and genetically diverse; they are generally
found in low numbers but have a low infective dose (<100 particles); they
are epidemiologically associated with propagated outbreaks, and they appear
to be enviromentally persistent. NLVs are able to resist chlorination (10 ppm),
can persist for 2 months at 4°C with a 50% reduction in infectivity, and are
not affected by quaternary ammonium salts and anionic detergents. Dr. Jaykus
and her colleagues performed a study to determine whether weight applied to
lettuce, surface-drying time, and use of wet vs. dry lettuce increased viral
transfer from surfaces to lettuce. Increased weight applied to the lettuce appeared
to have no effect on virus transfer, but viral transfer occurred more frequently
when the lettuce was wet. Surfaces that were dried for 10 minutes were able
to transfer NLVs to both dry and wet lettuce, whereas surfaces dried for 30
to 60 minutes did not transfer any virus to dry lettuce.
Dr. Sagar Goyal, of the University of Minnesota, discussed viral indicators
and methods of detection. Human enteric viruses (HEV), such as Hepatitis or
caliciviruses, can be found in feces, water used to irrigate produce, estuarine
water for shellfish, and wash or rinse water, as well as being present in or
on food handlers or contaminated surfaces. These viruses can occur at any stage
of the processing operation, from preharvest to transport of the final product.
Therefore, an indicator organism or new detection methods are needed. Characteristics
of an ideal indicator organism would include being present when pathogens are
present, having similar persistence and growth patterns, having similar resistance
to environmental stresses or disinfectants, and being non-pathogenic. Because
fecal indicator bacteria are not really effective in detection of HEVs, alternate
indicators such as Clostridium perfringens, Salmonella, and coliphages can be
used. F-RNA plaques, a heterogeneous group of RNA coliphages, are reliable indicators
of HEV because they are more resistant to ultraviolet light than fecal coliforms
are. In addition to viral indicators, new detection methods for preventive surveillance
or outbreak situations are also needed. Currently, there are no methods for
detection of viruses in foods, except for shellfish. Viral detection includes
liquefaction of a food, elution or precipitation of the viruses from the food,
investigation of PCR inhibitors and cytotoxicity, and percent recovery of the
viruses. Because no single method is suitable for all food types, new methods
applicable to groups of foods need to be developed.
Dr. Dean Cliver, of the University
of California-Davis, discussed control strategies with relation to foodborne
and waterborne viruses. Primary control measures include preventing contamination,
through use of chemical cleaning, proper handwashing, and biodegradation of
the viruses. Inactivation of the virus can be achieved by application of ultraviolet
light to surfaces or by use of clean water, drying, and heat. In terms of detection,
RT-PCR can be used, but only if the RNA is in good condition. If the capsid
of the virus is badly damaged, the RNase will destroy the viral RNA. If the
capsid is mildly damaged, protease may facilitate RNase action. To control foodborne
viruses, viral or fecal contamination of food must be prevented. The best mode
of prevention is still thought to be handwashing.
S03
— Development in Intervention Technologies to Enhance Produce Safety
Renee M. Raiden, Virginia Tech and Brian Yaun, Virginia Tech
This symposium introduced many different developmental technologies that are
being researched in an attempt to increase safety of produce throughout the
United States. Brian C. Hampson, from California Polytechnic State University,
discussed advantages of using ozone to increase produce safety. Its high oxidation
potential allows it to be used as a fumigant for produce storage rooms or as
an aqueous water treatment to aid in the recycling of water throughout processing
plants. Howard Q. Zhang, from Ohio State University, discussed pulsed electric
fields, which have been shown to reduce microbial loads in juices. This process,
which is carried out in static or continuous processing lines, ultimately causes
disruption in cell membranes. Low dose irradiation also kills microorganisms,
by breaking water molecules into radicals that cause disruption of cell membranes.
Brendan A. Niemera, from USDA-ARS-ERRC, explained that when irradiation is used
at low doses, it has no sensory impact on produce. However, once doses exceed
5 kgy, detrimental sensory characteristics are noted in foods. High pressure
processing, introduced by Dallas G. Hoover, from the University of Delaware,
and is best used for products that are not intact, because the pressure applied
may cause collapse of structure. Hoover specifically discussed the success of
using high pressure for processing oysters, whose structure would not be adversely
affected by the use of such high pressures. Active packaging is another innovation
discussed in this symposium. Kay Cooksey, from Clemson University, described
methods to deliver antimicrobial agents to food products through packaging.
Active packaging is regulated as an indirect food additive. One area of research
is prevention of mold growth in strawberries through chlorine dioxide diffusion.
Factors that become important in the use of active packaging include water activity,
pH, temperature and polymer diffusion from the package. Finally, Bassam A. Annous,
from USDA-ARS-ERRC, concluded the symposium with ideas on the development of
“experiment- friendly” equipment that can utilize and control many different
factors simultaneously during processing. Specific areas of concern were the
uses of incremental controls and the ability to contain pathogens.
S04 — Safety
of Latin-Style High Moisture Fresh Cheese
Shiao Mei Lee, University of Georgia and Paola Sabina Contreras,
Laboratorio DeAlta
Latin-style
cheese is soft cheese that has a high pH and high moisture content. These characteristics
do not provide sufficient barriers to limit growth of pathogens such as Listeria
monocytogenes, which has been implicated in several outbreaks. Production
of Latin-style cheeses does not utilize milk that has been pasteurized before
elaboration of the cheese. Use of pasteurized milk would eliminate competitive
flora and L. monocytogenes, but this
is not the complete solution. The lack of new and modern machinery, as well
as resistance to changes in cultural habits, represent major barriers to the
production of safe Latin cheeses. The panel of presenters suggested providing
more education to consumers and producers with regard to the need to use pasteurized
milk to make cheese. An infusion of financial support in Latin America is also
needed for purchasing manufacturing equipment and for providing education
regarding Latin-style cheeses, which have also become desired products in the
USA.
S06
— Minimizing the Risk of Salmonella
Enteritidis in Shell Eggs
Joshua Gurtler, University of Georgia and Kari Shoaf, University
of Nebraska-Lincoln
Symposium
06, entitled “Minimizing the Risk of Salmonella
Enteritidis in Shell Eggs,” discussed current problems associated contamination
of shell eggs with Salmonella Enteritidis
(SE) and strategies to prevent the organism’s transmission, contamination, and
growth. Dr. Robert E. Brackett, Director, Food Safety, FDA-CFSAN in College
Park, MD, presented an overview of the risks associated with SE infection in
shell eggs and discussed the symptoms, duration, and disease course of SE infections
in humans. Dr. Brackett emphasized the fact that the occurrence of SE infection
in humans is not decreasing. He explained
the 1999 USDA Egg Safety Action Plan implemented by the President’s Council
on Food Safety and first introduced by President Bill Clinton’s December 10,
1999 weekly radio address (www. foodsafety.gov/~fsg/ceggs.html). Numerous programs
and agencies are involved in this national prevention program designed to reduce
the occurrence of SE in shell eggs. Dr. Brackett suggested numerous approaches
to this problem, including increasing research to develop intervention plans
and determining the mechanisms of pathogenicity. Other possible solutions involved
implementing safety assurance programs, educating the public, and increasing
regulatory efforts. The USDA has set the year 2010
as a deadline for the “Elimination of SE illnesses associated with egg
consumption,” with an interim goal set for 2005 to “reduce by 50% the number
of egg-associated SE illnesses.” Dr. Richard K. Gast, of the USDA, spoke of
the risk factors for SE infection in laying hens. He suggested that the best
time to prevent contamination of eggs is post-harvest; however, pre-harvest
contamination prevention should also be considered. The risk factors involved in
SE infection in laying hens include the source of bacterial introduction, the
method of transmission, and the susceptibility of laying hens to the disease.
Dr. Mark Walderhaug, of the FDA-CFSAN, discussed environmental testing for SE in
layer houses. He elaborated on the FDA’s policy and protocol while describing
traceback investigations of SE outbreaks. Dr. Robert R. H. Davies, of the
Veterinary Laboratories Agency in Surrey, gave an overview of the current
reduction in SE contamination in shell eggs in the United Kingdom; however, no
explanation of this reduction could be given. Dr. Patricia A. Curtis, of Auburn
University, discussed emerging technologies for rapid cooling of shell eggs. It
was pointed out that shell eggs must be kept cool from laying to consumption.
She suggested that rapid cooling leads to less SE growth within shell eggs. Dr.
Brian Sheldon, of North Carolina State University, discussed the pasteurization
of shell eggs, which was developed to effectively address SE and egg safety
issues. He described in-shell egg pasteurization as a thermostabilization
process that denatures the outer albumen to maintain interior egg quality,
reduce evaporation rates, reduce bacterial contamination, and devitalize fertile
eggs. Finally, Dr. Shelly McKee, from the University of Nebraska in Lincoln,
made a presentation concerning HACCP for shell egg packing and processing. McKee
and colleagues developed five different HACCP plans for varying egg production
processes to minimize SE risk to the consumer. Two of these processes were
discussed, including processes dealing with pasteurized egg products such as
hard-boiled eggs and other specialty eggs. This informative symposium provided
numerous explanations for current problems of Salmonella
Enteritidis in shell eggs as well as solutions for reducing the risk of SE
infections.
S07
— Microbiological Food Safety at Retail
Renee M. Raiden, Virginia Tech and Brooke K. Seeman, Virginia Tech
This symposium discussed microbiological food safety at the retail level. Shelly
Huddle, of the CDC, began the symposium by introducing statistics related to
the occurrence of foodborne outbreaks in restaurants, as well as common agents
involved, as reported by several surveillance systems that the CDC has in place.
For the years 1973-1999, 55% of all reported outbreaks were linked to restaurants
and delis. Frank Busta, from the University of Minnesota, pointed out that defining
potentially hazardous foods is related to the potential for pathogens to grow
in the food. In 2001, the definition “potentially hazardous food (PHF)” was
replaced by “temperature controlled for safety (TCS).” This change meant that
foods considered potentially hazardous were those that required temperature
control to remain safe. Tim Freier, from Cargill, explained the importance
of microbiological controls throughout every stage of food production. Such
controls include good agricultural practices (GAPs), prerequisite programs implemented
at processing plants, training, and new processing innovations through the use
of irradiation and other developing processes. Sheila Cohn, from the National
Restaurant Association, introduced the topic of microbial control strategies
at the retail level, emphasizing the importance of employee training and food
safety education throughout restaurant chains to keep food safe for consumers.
The control and incidence of viruses at retail was also addressed by Susan Sumner,
from Virginia Tech. She explained that, unlike bacteria, viruses do not replicate
in food systems, and their incidence is usually under-reported. Viruses typically
come into contact with foods through point source contamination such as infected
handlers or raw sewage. Finally, David Theno, of Jack-in-the-Box, Inc., ended
the symposium by stressing the importance of management of food safety risks
at retail. He proposed setting realistic goals and establishing a protocol and
a threshold at which action would be taken. Retailers must then follow through
with employee education and training as well as implementation of available
technology, including a contigency system in case problems arise.
S08
— Extended Shelf Life Meat Products–Issues and Interventions
Kelley Felkey, University of Florida and Sally Foong, Iowa
State University
This session covered research on problems related to shelf life in meat products,
and ready-to-eat (RTE) products, and to interventions. Dr. Bruce Tompkin, of
ConAgra, introduced the session with an overview of microbiology in extended
shelf life products. “Extended” is defined as being held in storage for more
than is usual in normal, commercial practice. This is not applicable in all
countries. Extended shelf life helps to eliminate economic loss, delivers a
consistent product, improves inventory, eliminates large production and allows
products to be distributed longer distances. Packaging improvements have also
been made in recent years, progressing from paper wrapping to present day modified
atmospheres and cooking in a bag. There have been better temperature and environmental
controls with such products as sodium lactate and diacetate. Code dating on
RTE assists in traceback investigation in the event of a recall. Studies have
been performed on spoilage organisms for more than 90 years; more recent work
has focused on Listeria monocytogenes.
Dorota M. Broda presented information regarding low-temperature-growing Clostridia.
Commonly associated with vacuum-packed chilled meats, raw or cooked, the organism
causes bag extension and spoilage, with a rank odor. Detection methods can be
difficult and a technique utilizing Polymerase Chain Reaction (PCR) is currently
being developed. Sources of Clostridia could be boning rooms, feces, soil and
water on farm, and pelts. Controls can be implemented in pre-slaughter, dressings,
post-dressing, boning, and packaging. A blown pack is often the result of bad
hygiene during processing.
Dr. Richard A. Holley discussed the impact of green discoloration in cured
meat products. The discoloration is often associated with spoilage that has
sour, slimy, and gaseous characteristics at 4°C. His work centered on the organisms
responsible for causing this discoloration. Some microflora associated with
cured meats are Lactobacillus, Brochothrix, Aerococcus, and Carnobacterium viridans.
The Aerococcus species was isolated as the probable cause of spoilage with green
discoloration. Some treatments such as sodium diacetate and sodium lactate may
be helpful in reducing or eliminating this spoilage.
John Luchansky presented an update
on the prevalence and persistence of L.
monocytogenes in RTE products. This presentation demonstrated the effectiveness
of antimicrobials against L. monocyto-genes.
In recovering L. monocytogenes from
frankfurters and packages, the USDA/ARS compared a package rinse technique with
the current USDA/FSIS method. All packages were naturally contaminated and counts
were obtained from both methods. Potassium lactate, utilized as an ingredient
in batter, can be effective as an antimicrobial at low levels; however, heating
at high temperatures is the best method of reducing L.
monocytogenes populations.
Robin Kalinowski discussed intervention
strategies utilized at ConAgra Foods, Inc. after problems with Clostridia
contamination. The problems arose in their cooked beef and poultry cook-in-a-bag
products. The first solution was to reduce code dates, but customers wanted
a longer shelf life (at least 45 days). Other interventions included elimination
of Clostridia from the environment,
modification of the storage temperature, and addition of antimicrobial ingredients.
John Sofos discussed the topic of additives as interventions in RTE products.
The studies he discussed involved frankfurters, bologna, and beef jerky. All
studies were performed to control post-processing surface contamination by L.
monocyto-genes. The beef jerky studies also tested additives as inhibitors of
Salmonella and E. coli O157:H7. A variety of additives were tested, among them
sodium acetate, sodium diacetate, sodium lactate, potassium sorbate, potassium
benzoate, acetic acid and lactic acid. Not all additives were capable of inhibiting
bacterial growth.
S09
— Cooperating to Improve Foodborne Outbreak Investigations
Karol M. Gailunas, Virginia Tech and Megan L. Hereford, Virginia
Tech
Jack
Guzewich, of the Food and Drug Administration, spoke about the “team” effort
required during a foodborne outbreak investigation and how each of the “players”
has specific roles and responsibilities. The team, made up of members from epidemiology,
laboratory, and environmental areas, work together along with different levels
of government, including local, state, federal and international. There must
be a partnership among the government, academia, and private sectors to create
the working relationships required for a successful outbreak investigation.
Each player has a specific role in surveillance, detection, investigation, food
association, trace back, and source investigation.
Rob Tauxe, of the Centers for
Disease Control and Prevention, gave an overview of the surveillance and epidemiological
activities that occur during a foodborne outbreak investigation at the CDC.
He emphasized that the most important part of epidemiological investigations
is the surveillance that occurs daily in county and state health departments.
Of the 6 stages in an outbreak investigation, the first uses surveillance to
detect an outbreak that has occurred. The next two stages involve developing
possible explanations and testing the related hypotheses. Stage 4 is a reconstruction
of the location and time the contamination occurred, the epidemiological trace
back; if the findings of the investigation do not converge on a specific food
and place, stages 2 and 3 must be reconsidered. Stage 5 occurs when it is determined
how the contamination most likely occurred, and Stage 6 consists of developing
a plan for long-term prevention so that this type of outbreak will not happen
again.
To show examples of how epidemiological investigations of foodborne outbreaks
are done, two Epidemic Intelligence Service (EIS) Officers from the CDC spoke
about recent investigations in which they were involved. The first, Donita
Croft, explored an outbreak of E. coli O157:H7 that occurred in the fall of
2001. Using the 6 stages discussed earlier, she explained how her team associated
the bacteria with a pancake breakfast held at a university stock pavilion. Her
team found that bacteria were transmitted by contact with cow manure in contaminated
sawdust bedding on the floor of the pavilion. The second EIS officer to speak,
Anita Gupta, discussed an outbreak of Salmonella Newport that occurred between
1998 and 2001. Her team found that there was illness among humans and dairy
cattle and that the illness was passed between the humans and cattle intermittenly
for about 3 years.
Dr. Jeff Farrar, Chief of the
Emergency Response Unit of the California Department of Health Services, spoke
on the importance of environmental investigations in foodborne outbreaks. He
stressed the importance of correct and proper measurement during investigations
and careful documentation of these processes. Lab and epidemiological findings
should be reviewed and critiqued. Farrar also emphasized the need for cooperation
between agencies in these foodborne outbreak investigations. Investigations
should include a review of people (employee food safety knowledge and training),
equipment (maintenance and use), and economics (such as how supply vs. demand
affects SOPs).
Dr. Mary Palumbo, of the California
Department of Health Services, discussed the environmental investigation of
a 2000 Salmonella outbreak associated
with almonds in Canada and California, and a 2001 outbreak of Shigella
associated with five-layer bean dip. In the almond outbreak investigation, the
review process considered the process flow diagram of the almond processors,
and this led to samples testing positive for Salmonella
at one of four huller/sheller locations and at four of twenty-three farms.
In the end it could not be determined how the farms were contaminated, but
actions were take to prevent further outbreaks. The huller/sheller was
disinfected, and all almonds from positive fields were treated separately and
processed with a kill step. After the Shigella
outbreak, consisting of 217 cases in California and more in various other
states, there was a voluntary recall of the five-layer bean dip. Following the
investigation, it was concluded that the source of contamination was most likely
an ill employee, although contaminated produce could not be ruled out.
Dr. Mindy Brashears, of Texas Tech University, spoke about the university perspective
on recalls and outbreaks. She noted that the number of microbial associated
recalls has increased compared to previous years and that not all recalls are
associated with outbreaks. Universities must work with processors and regulatory
agencies to provide valuable research, extension, and teaching. It is also important
that the media be provided with the correct facts quickly so that they reach
consumers. Dr. Brashears discussed the August 1997 Hudson Foods recall due to
Escherichia coli O157:H7 in ground beef. The results of this recall were two-fold:
more aggressive testing programs for E. coli O157:H7 by the USDA, and better
lotting and coding adopted by processors. The number of E. coli O157:H7 recalls
has increased since this incident.
S10
— Integrated Approaches to the Study and Control of Foodborne Pathogens in Meat
and Poultry
Walairut Chantarapanont, University of Georgia and Suphachai Nuanualsuwan,
University of California-Davis
The
integration of farm‑to‑plate approaches to assure food safety, based
on research investigating all possible routes of transmission, is becoming
recognized as an effective means of reducing foodborne illness from bacterial
pathogens. The need to extend the focus of intervention efforts to on‑farm
sources of human pathogens, food animals, is clear. The challenge presented is
to design studies to determine important risk factors for sources of enteric
zoonotic pathogens during production on the farm to address the human health
burden.
This symposium described how studies
conducted in Iceland, New Zealand, Denmark and the United States have approached
the challenge of integrating the application of multiple disciplines, e.g. microbiology,
molecular biology, epidemiology (using geographic information system or GIS
and spatial epidemiology), statistics, and risk assessment. Topics in microbiology
centered on sampling and detecting microorganisms. Molecular biology combined
with statistical software was used to correlate genetic and epidemiological
information among isolates. These available fields were integrated to extend
the study of sources and risk factors of foodborne pathogens from the entire
primary production sector (on‑farm, hatchery, etc.) through exposure to
consumers.
S11
— Listeria Research Update
James Folsom, University of Florida and Yash Burgula, University
of Minnesota
Jeffrey
M. Farber spoke about a novel new approach to sub-typing Listeria monocytogenes,
which causes about fifty or sixty cases of disease in Canada annually. The new
technique, it is hoped, will be able to differentiate between L. monocytogenes
isolates of varying pathogenicity. This new method has been named MultiLocus
Sequence Typing (MLST). For more information, please see the web resource http://www.mlst.net.
Bala Swaminathan, of the CDC,
replaced Sophia Kathariou at the last minute. Dr. Swaminathan spoke about efforts
to differentiate Epidemic Clone II (ECII) isolates from other isolates of L.
monocytogenes.
Martin Wiedman spoke about progress
made in his lab regarding a definition of human pathogenic strains of L.
monocytogenes. Ongoing work in his lab will help determine if there are
methods that can allow the differentiation of harmful strains of L.
monocytogenes from harmless strains. The web resource http://www.pathogentracker.net
has further information.
Byron Brehme-Stecher detailed the progress made toward the use of fluorescent
in situ hybridization (FISH) to detect L. monocytogenes. The technique has been
made possible by use of peptide nucleic acid (PNA) probes. A powerful method
of detecting and enumerating L. monocytogenes could result from the combination
of PNA probes with flow cytometry.
S12
— Current Issues in Seafood Safety
Nancy DeTrana, University of Tennessee and Rico Suhalim, University
of Georgia
Approximately
26% of the foodborne outbreaks in the US involve seafood. Ciguatoxin, histamine,
Vibrio spp., C.
botulinum, viruses and paralytic shellfish poisoning are some of the agents
identified in seafoodborne diseases. In addition, algal bloom can become a human
health hazard when there is an increase in water temperature and in availability
of wastes that serve as nutrients. Marine biotoxins are neurological in nature.
Among bacteria, V. parahaemolyticus is
a significant cause of foodborne disease, and a risk assessment model is
currently being developed. To prevent and contain outbreaks of disease caused by
Vibrio spp., proper education,
warnings, and harvest controls (depuration, area closure, and refrigeration) are
needed. Contrary to popular belief, hot sauces of any kind and/or alcohol do not
inactivate the organisms.
S13
— Controlling Clostridium perfringens Hazards during Cooling
Suphachai Nuanualsuwan, University of California-Davis and
Sally Foong, Iowa State University
Clostridium
perfringens is a continuing concern to the food service industry. The abilities
of this pathogen to form heat‑resistant spores and to grow at a very rapid
rate at relatively high temperatures are the major contributing factors leading
to food poisoning. Spores of C. perfringens,
which have a decimal reduction value at 99oC of 26 to 31 min, can be expected
to survive the pasteurization temperatures and times used to cook or prepare
foods in food‑service operations. Although the temperature range for growth
of C. perfringens is 6 to 52.3oC,
rapid growth occurs between 35 to 48.9oC. The short generation time of the organism,
7.1 to 20 min, in the rapid‑growth temperature range means that after
the spore has germinated, fast cooling of foods is critical. Because of the
potential health hazards associated with cooling cooked foods, the United States
Department of Agriculture (USDA) requires that, during cooling of certain meat
and poultry products, the relative growth of C.
perfringens should not exceed 1.0 log10.
This symposium was designated
to present information on ways to control the rapid growth, based on current
knowledge of C. perfringens biology,
by experimenting with various kinds of cooling system, e.g. blast freezing,
blast chilling and blast cooling with different rates of success. In addition
to physical methods, some chemical agents are being studied in poultry products
as possible
anti-clostridia agents, e.g. sodium diacetate, sodium lactate, and sodium
acetate.
Risk assessments and predictive models are other alternatives to controlling
the growth of C. perfringens. Researchers have developed predictive models that
can be used to predict small to moderate amounts of relative growth of C. perfringens
from spores during cooling of cooked cured and non-cured meat products. The
predictive equations are being used in risk assessment models for cooked meats
and have been incorporated into the USDA pathogen modeling computer program,
which is available on the Eastern Regional Research Center Web site.
S14
— Innovation in Retail Food Safety Management Systems and Technology
Shiao Mei Lee, University of Georgia and Rico Suhalim, University
of Georgia
Supermarkets
are offering more foods that accommodate today’s “on-the-go” lifestyle, leading
to greater emphasis on home meal replacements (HMR) and their safety. HMRs offer
a variety of quality prepared foods that resemble restaurant-quality food rather
than traditional frozen food selections. Safety of HMRs has come under increased
scrutiny. HACCP systems in many food companies ensure the production of
safe food and lower the cost of “value-added” products. Companies are preparing
higher standards and working closely with food suppliers to produce safe food
with lower cost and high quality. The presenters also talked about using technology
as a tool for training employees and for inspections. Some of the problem areas
that need to be addressed are storage temperature, sanitation, personal hygiene,
and pest control. Following standards and guidelines are key to producing wholesome
foods that serve as HMRs.
S15
— Alternatives in Dairy Waste Management: Create New Products or Generate Power!
James Folsom, University of Georgia and Leslie Thompson, Kansas State
University
This session discussed the sources of dairy waste and uses for the waste. The
two sources of waste that are being targeted by the industry for further use
are the milk product left in pipes and tanks during processing, and the wastes
produced by cattle on dairy farms. The technologies discussed to recover milk
products included reverse osmosis, TLSL, SPN project, and thermal depolymerization
(TDP). These technologies recover lactose, whey protein concentrate, lactic
acid, fertilizer, oil, gas, carbon, and calcium magnesium acetate, respectively.
Product recovery from dairy processing allows reduction of BOD. The utilization
of methane is also a pro-missing development. The biogas produced by modern
digesters can be used to produce electricity for use on the dairy farm and more.
There are presently 36 projects in California with 7.6 megawatts biogas generating
capacity. The waste left after digestion can also be used as fertilizer.
S16
— Chronic Wasting Disease and Other Transmissible Spongiform Encephalopathies
Megan Herford, Virginia Tech and Angela Hartman, Virginia Tech
Dr.
Dean Cliver, of the University of California-Davis, gave an overview of
Transmissible Spongiform Encephalopathies (TSEs). TSEs are accumulations of
abnormal prions in the brain that lead to spongiform degeneration. These low
mole-cular weight proteins are found in the central nervous system and are
thought to be responsible for a number of diseases, including Chronic Wasting
Disease (deer and elk), scrapie (sheep), bovine spongiform encephalopathy, and
Creutzfeldt-Jakob disease (humans). All TSEs are fatal, and some are even
contagious. The response in the United Kingdom to the occurrence of BSE in
cattle was the slaughter of whole herds to eradicate the presence of the
disease. It is now recognized that the TSEs can be spread between species, and
its occurrence in cattle and now in humans has prompted a massive research
effort. There is now concern that CWD can be spread to humans.
Dr. Katherine O’Rourke, of the
USDA-ARS, spoke about the development of diagnostic tests for Chronic Wasting
Disease. CWD, a disease of deer and elk, is actually a family of diseases, as
it varies in species and location. Currently, live animal tests and postmortem
tests are available, but the brain remains the most reliable source for diagnostic
testing. To develop more reliable live animal tests, researchers are looking
for ways the disease may be transmitted. Routine necropsy of farm animals is
regulated by the government, and surveillance is also performed on wild herds.
To develop better diagnostic testing, large numbers of animals must be tested.
Currently there is a significant need for personnel and laboratories for CWD
testing, lack of which delays test result availability. In the future, CWD testing
is expected to be species specific, and tissue specific, and to be better designed
to meet volume demands.
Dr. Suzette Priola, of the Laboratory
of Persistent Viral Diseases, NIH, NIADI, discussed how TSEs such as scrapie,
Creutzfeldt-Jakob disease, BSE and CWD could cross species barriers to infection.
She suggested that ingestion or inoculation of the prion most likely causes
infection, although the infectious agent is unclear. A study with transgenic
mice suggested that conversion of the normal prion (PrP sen) to the abnormal
prion (PrP res) might be related to the sequence of amino acids in the protein
of the prion. In vitro studies also show that susceptibility to cross-species
transmission is based on species-specific abnormal prion formation; therefore,
the PrP sequence can control species barriers in TSEs. She discussed the relative
strengths of conversion of PrPsen to PrPres molecules in different species.
For example, BSE & CWD abnormal prions convert normal cervid PrPsen better
than noncervid PrPsen to PrPres. Therefore, BSE & CWD transmission to humans
and other noncervids may be restricted.
Dr. Elizabeth Williams, of the
University of Wyoming, discussed the epidemiology of CWD in wildlife. She noted
that the core epidemic area of CWD occurs in free range deer, and farmed elk
contribute to the commercial movement of the disease in the midwestern U.S.
Currently the core endemic focus is on hunter harvest surveillance, which has
contributed more than 10,000 animals to be tested from 1983-2001. The foci in
free-range deer are thought to be game farm associated, but this is not confirmed.
Overall, epidemiological investigation of CWD has shown that in the core endemic
area, the disease has a slow geographic spread and relatively high prevalence.
As more farmed animals are moved in commerce, a higher number of affected herds
is likely. Recently recognized foci are game farms. As affected animals are
moved in commerce or as animal agents are moved geographic expansion of the
disease will occur.
Dr. Lynn Creekmore, of the National
Animal Health Programs, of the USDA spoke about the challenges in controlling
CWD and of the current control measures used for CWD. She noted that effective
control prgrams for CWD in alternative livestock such as farmed elk and deer
has been difficult because of multiple regulatory authorities, fragmented jurisdictional
frameworks, and multiple cervid species industries. Also, the maximum incubation
period and the time from infection to the shedding period is unknown, and no
reliable antemortem diagnosis for elk is available. Although these factors present
challenges in controlling CWD, the USDA has recently proposed a control program.
This program, for farmed elk, includes fencing requirements, animal identification,
herd inventory, and surveillance of deaths over the past 16 months. In response
to positive herds, the program calls for depopulation or quarantine with selective
depopulation. In a herd that is traced forward, removal and testing or quarantine
would be required, whereas a traced back herd would require quarantine. Current
responses for the control of CWD also include a CWD task force, a national program,
and a declaration of emergency & CDC funds for traces, positive herds, and
surveillance.
S17
— Applications of DNA Chip Technology in the Food Safety Area
Kali Kniel, University of Georgia and Manan Sharma, University
of Georgia
As
an emerging area of great potential for use in food safety, this symposium spotlighted
the use of micorarray technology, more commonly referred to as DNA or gene chips,
and their various applications, concentrating on their use in the identification
of foodborne pathogens. Microarray technology is unique in that it allows for
high throughput analysis, unlike that available through other techniques. The
gene chips contain an array of DNA or RNA molecules printed onto a solid or
semisolid substrate. This allows for fast processing and subsequent analysis
of gene expression and DNA composition. While gene chips are most common at
this time, arrays composed of proteins, cells, tissues, and small molecules
are also available. With all microarrays, standards must be available to allow
duplicate experiments to be performed and to ensure that standard terms are
used across the industry. This is currently a problem with this technology,
but it will be overcome with increased use, comfort by the users, and time.
The potential for the use of gene
chips in food safety is immense, including, but not limited to, use as a diagnostic
tool in food samples, comparison of virulent and nonvirulent strains, typing
of strains involved in foodborne outbreaks, evaluation of the effectiveness
of drug treatments, and analysis of the selection pressures that occur in different
food matrices. Various industries could use this technology to analyze gene
expression, evaluate antibiotic resistance, or identify differences in phenotypes
observed in various food matrices. Microarray technology can be used in conjunction
with PulseNet, which first demonstrated the importance of molecular subtyping
for foodborne disease surveillance. Additionally, this technology can be optimized
to fit specific situations, depending on the purpose and the size of the genetic
sequence. To date, gene chip technology has been used to study the virulence
among different strains of Listeria monocytogenes.
This technology allows scientists to discriminate between small changes in types
that occur within a single outbreak. Similar successful applications have been
used in studying Campylobacter species,
in particular looking at the high variability of gene expression correlated
with phenotypic characteristics. In summary, microarray technology, in particular
gene chips, have great potential for use in the food industry for identification
and differentiation or organisms in foods. Multiple pathogen chips are under
development as the use of this technology continues to grow.
S18
— Sanitary Design of Plants and Equipment
Rico Suhalim, University of Georgia and Adriana Velasquez, University
of Nebraska-Lincoln
Food
companies are required to do their homework before designing a food plant and
buying a piece of equipment. There are many factors to consider, from the choice
of floor covering and location of equipment to what goes overhead. All these
choices can in the long run increase the ease of plant and equipment sanitation
to prevent harboring microorganisms. Food contact surfaces should be smooth and
free of cracks and crevices to avoid pathogen danger zones. Equipment should be
simple, smooth, accessible and easy to disassemble. Ease of cleaning could
translate to faster cleaning, fewer sanitation workers, and reduction of
spoilage and pathogen issues. Stainless steel with built-in anti-microbial
coating is now available. Beware of microorganisms hiding in lubricants,
bearings, wiring conduit, and electric switches.
S19
— Risk Assessment of Food Workers’ Hygiene Practices and Intervention Strategies
Matthew Evans, North Carolina State University and Leslie Thompson,
Kansas State University
Food
service workers can directly or indirectly contribute to bacterial, viral, or
parasitic illness outbreaks through poor personal hygiene and sanitation
practices. This symposium reviewed the identification of hazards such as cuts
and sores on workers’ hands, inadequate or non-functioning bathroom
facilities, and multiple infections of symptomatic and asymptomatic workers.
After exposure to the pathogen has occurred, the probability of illness is a
complex function of factors associated with a specific disease, including
several factors such as the host and the pathogen, including its survival and
growth capabilities. Other factors associated with exposure, such as the
environment, the food vehicle, and indigenous microbial competitors, as well as
intervention measures employed to reduce or prevent microbial contamination,
were discussed. An exposure assessment takes into account the likelihood of
exposure by various means such as in production, or processing, by different
routes and pathways, and in relation to the frequency of contamination, portion
sizes consumed, consumption patterns of the population, ecology of different
foods, and characteristics of the pathogen of concern. Quantitative risk
assessment models of worker hand washing procedures and of the
cross-contamination of raw chicken exudates containing Salmonella
or Campylobacter with ready-to-eat
(RTE) foods were presented to demonstrate the degree of risk to human health.
The first assessment addressed handwashing procedures among food preparation
workers by use of computer simulations to identify critical control points in
their hand washing procedure so as to reduce the risk of bacterial contamination
of food products. The second simulation used bootstrap methodology to decrease
the variability of uncertainty in dose-response models. Finally, the
psychological aspects of the workers’ hygiene training, including factors
which may determine a food handlers’ behavior such as organizational climate
or culture of the workplace, the attitudes and beliefs of the workers, human
error analysis, and social marketing approaches, were reviewed to determine
their usefulness in worker training.
S20
— Customized Approaches to Microbiological Risk Assessment
Matthew Evans, North Carolina State University and Kimberly
Stanley, University of Tennessee
Food safety has both a risk analysis and a risk assessment framework. The framework
for risk analysis consists of a policy-based risk management area and a science-based
risk assessment area. The key to a successful assessment program is communication
between these two areas. Ongoing work is presented to the Codex Committee on
Food Hygiene, and feedback is required from risk managers to risk assessors;
this now occurs only once a year. This need for greater interaction has been
recognized and is being addressed. For four ongoing studies of bacterial contamination
of food, various approaches were examined. For example, a quantitative risk
assessment for the risk of Listeria monocytogenes in ready-to-eat foods from
retail to consumption consisted of selecting certain ready-to-eat foods to represent
various types of products, which were then modeled from retail to consumption.
For an exposure assessment, the production-to-consumption approach is not always
required, and often a modular approach is easier to adapt to risk assessments.
For all of these assessment types, flexibility is a necessity as is interaction
with risk management and a multidisciplinary approach should be taken.
Risk ranking is a very important
type of quantitative risk assessment. Ranking is generally emphasized more than
values because ranking gives people a frame of reference, especially if these
people are not technically trained. Three levels of data exist for risk assessments:
data collected specifically for risk assessment, data from research done for
other purposes, and expert opinions. The main principle for risk assessment
and these data is to “keep it simple, but no simpler.”
Mr. Whiting identified good data
as being both complete (objective) and relative to the risk assessment question.
The quality of data is relative to its usage in risk assessment. This is often
determined by performing sensitivity and importance analyses. Risks are ranked
to determine data gaps, research needs and to show the relative relationships
between these. Ranking also helps provide insight into the predominant factors
responsible for circumstances when high levels of uncertainty exist.
Risk profiling is used to describe
a microbiological food safety problem and its context. This type of profiling
works to determine the size and nature of the problem and what actions are necessary
to combat the situation, as well as whether a risk analysis should be carried
out. Mr. Notermans used a hypothetical situation to describe the risk profiling
of fruits and vegetables that are eaten raw. The factors that must be taken
into consideration for this situation include production practices, pathogens
of concern, commodities and aspects of concern, post-harvest measures, the management
of risks, and consumer perceptions and wishes.
A risk profile serves to provide
general background information, and these profiles are generally relatively
easy to carry out. Various conclusions obtained from risk profiling may describe
the source of the microbiological hazard, evaluation of the hazard’s contribution
to health problems, incidence data and severity of adverse effects, available
intervention options, potential consequences of actions taken and the distribution
of risks and benefits
Mr. Ross led a discussion regarding
the usage of specialized software as a support tool for Microbiological Risk
Analysis (MRA). Quantitative MRA is a rather expensive process, requiring a
considerable amount of expertise along with specialized software. Mr. Ross provided
a demonstration of a program in Microsoft Excel, which used “list boxes” and
provided qualitative prompts and questions. Eleven questions were designed for
the risk analysis, including the realm of exposure, population size, and cooking
procedures.
There are limitations to this
program. First, it is only an “approach” to risk analysis, not a tool or model.
The performance of the tool is unproven, it does require some level of expert
knowledge, it yields average values, and its sensitivity is limited. Some improvements
that could be made include asking more objective questions, having more discrete
steps in the model, and devising better weighing factors. According to Mr. Ross,
this program is a start and there are many possible improvements. It is useful
for risk screening and ranking, as well as for communicating the idea of food
safety risk analysis and the factors important in establishing the analyses.
Although risk analysis can be used by governments to obtain overviews of food
safety, industries may better benefit from Microbiological Risk Analysis (MRA).
MRAs are of many different sizes, but the principles of a tiered approach are
as follows:
1) Rough Analysis—description of the population, risks, contributing factors,
worst
case scenario
2) Decompose most relevant steps—progresses quantitative insight on existing
data
3) Describe most relevant steps in full detail
Potential cons to MRAs include
the potential of less complete and flexible cases for future development and
data gaps. Deciding on rough levels could allow false confidence, and all critical
factors must be included. Positive aspects include the resource efficiency of
the process and the fact that it identifies the most risk-determining factors
and estimates their magnitude of influence. The tiered approach is very systematic,
and researchers are able to stop at any level.
The Process Risk model consists
of performing risk assessments in order to establish potential risks and to
gain understanding of the system. This gives direction for research, and the
ideal goals are to collect and evaluate information of concern and to act as
a channel of communication between groups.
There are various types of risk
assessment. Hazard assessment, which is a basic first step, is done in order
to simply determine whether risks exist or not. A qualitative approach consists
of developing a knowledge base of the risk issue, whereas a structural qualitative
approach deals more with risk profiling. A semi-quantitative approach converts
the understanding of the data at hand into a “model,” and a quantitative approach
transmits data into the characterization of the system, which does not have
to be complex. The process risk modeling approach is developed from the system
modeling concept and is used to create a model as a tool to provide insight
into the system.
S21 — Control
of Escherichia coli O157:H7 in Cattle
Shiao M. Lee, University of Georgia and Renee M. Raiden, Virginia
Tech
This symposium introduced many different areas that are being researched in
the attempt to control Escherichia coli O157:H7 in cattle. Francisco Diez-Gonzalez,
from the University of Minnesota, discussed the effect of forage feeding and
other dietary controls for reducing the prevalence of E. coli O157:H7. Forage
feeding has been found to reduce populations, and grain feeding may increase
populations by stimulating E. coli O157:H7 growth. Another topic, discussed
by Jeffery T. Lejeune, from Ohio State University, was the association of E.
coli O157:H7 with drinking water. It was thought that cleansing drinking water
with chlorine or ozone would reduce levels of E. coli O157:H7 in cattle. However,
it has been found that these controls have little effect on prevention of contamination
in cattle. Robin Anderson, from Southern Plains Agricultural Research Center,
explained that cattle are considered a natural reservoir for E. coli O157:H7.
The use of chlorate salt preparations as feed additives may lyse bacterial cells
in cattle, because the chlorate salt becomes bactericidal after 6 hours. Mindy
Brashears, from Texas Tech University, introduced the concept of competitive
exclusion. This incorporates probiotic bacteria such as proteus and non-pathogenic
E. coli as well as lactic acid bacteria to control levels of E. coli O157:H7.
It has been found that the addition of these competitive organisms reduces the
time that the animals shed the E. coli O157:H7. The use of vaccination was another
innovation discussed in this symposium. Andrew A. Potter, from the Veterinary
Infectious Disease Organization, described methods to reduce populations through
use of an enterhemorrhagic E. coli vaccine. This has been found to reduce numbers
and the duration of time that E. coli O157:H7 is shed. Finally Denis O. Krause,
from CSIRO Livestock Industries, wrapped up the symposium with an introduction
to the use of dietary supplements for control of bacteria in the tropical beef
production systems of Australia.
S22
— Current Practices in Produce Safety
Vivian A. Rash, University of Tennessee and Brooke Seeman,
Virginia Tech
Because
fresh produce consumption has increased rapidly since 1970, the number of
produce-associated outbreaks has also increased. Contamination is occurring on
produce and produce is consumed mainly via salads/bars (35.4% outbreaks
associated in the United States between 1990-1998). Approximately 75% of produce
associated with these outbreaks are domestic products. To prevent this, Bob
Gravani states that we have to stop the transmission of microorganisms and
recognize their sources. Manufacturing processes such as the use of recirculated
waters, failure to change this water, and improper treatment are major factors
in pathogen contamination. Also, produce must be grown in areas separated from
livestock areas to decrease on pathogen contamination.
As for the rise in numbers of
people suffering from foodborne illness, we have an aging population, more cases
of chronic illness and more immunocompromised patients who are more prone to
become sick from contaminated produce. Also, we are more aware of hygiene and
have a more complex food system. Microorganisms are able to adapt to different
environments and stresses and strains may be more virulent.
In his talk, Trevor Suslow discussed how risks differ with varied environmental
interactions. Contamination may come from unlikely places and thorough investigations
must be done in order to derive the source. For example, Salmonella was found
on mushrooms during the 2000-2001 growing season. The source was traced to gypsum,
which was being used in the casings. Thus, this led to the proposal that unique
risks are attached to organic farming. He said that currently there is not enough
data, but with proper regulations on safety, organic farmers are no more at
risk than non-organic farmers. He also addressed the issue of water filtration.
If water is filtered properly, then this can remove any concerns of waters used
for irrigations and surface washes, so that clean water means cleaner and pathogen
free produce.
Maintaining good manufacturing
practices is the key to having a reduced microorganism environment on minimally
processed produce. It will take implementation steps of the actual manufacturers
to achieve these higher quality foods.
S23
— Food Safety Education
Paola S. Contreas, Laboratorio De Alta and Rico Suhalim, University
of Georgia
Although
overall awareness of food safety is increasing among consumers, the perception
of personal risk tends is still slight. Many believe that the source of foodborne
diseases is due to the food they ate within 24 hours of illness. When asked
which factors keep food safe, most consumers indicate that hand washing, proper
cooking, washing food, and proper refrigeration are important factors. An FDA/FSIS
survey shows that 68% of consumers know when hand washing is necessary but that
48% of those do not wash their hands. Some of the recommended practices in food
safety that many consumers do not know include: maintenance of refrigerator
temperature, how long to store perishables, how to wash hands, how to wash cutting
boards, and how to wash produce. Failure to cook sufficiently is due to the
fact that few people use thermometers and that people serve food that has not
reached a safe temperature. Seniors are likely to follow recommended kitchen
and personal hygiene, whereas households with young children are less likely
to properly clean the kitchen. With regards to fresh produce handling, certain
groups, including males, high-income households, college/post-college graduates,
and persons who are 44 years of age and younger, are least likely to follow
the recommended practices. Food safety messages can be effective if we can identify
the seriousness of the illness, note who is at risk, describe control measures,
and reinforce the message.
Lecture
Topics
Ginny Moore, University of Wales Institute-Cardiff and Adriana
Velasquez, University of Georgia
The ICMFS Lecture on microbiological sampling plans by Susanne Dahms analyzed
different biometry plans to use in the food industry and research environments.
The diverse types of sampling plans were explained thoroughly, having been divided
into qualitative and quantitative categories.
These methods are widely used
in the laboratory to reject/accept data obtained from experiments.
Risk assessment of microbiological
hazards in foods: an international approach was discussed by Sarah Cahill (FAO)
and Peter BenEmbarek (WHO). The World Health Organization and the Food and Agricultural
Organization are working together on a joint project to establish common rules
and guidelines to be used worldwide to control microbiological hazards on foods.
Because of research done in the past and availability of information, popular
awareness of these hazards has increased. Also, with time new hazards emerge,
along with new risks and challenges. Because a more globalized food trade means
an increased risk of cross-border transmission of pathogens, food safety is
a global issue that requires global attention.
Some of the objectives of this
project are:
1. Generation of scientific info
2. Elaboration of guideline documents
3. Data collection
4. Information and technology transfer
5. Use of risk assessment within a risk management framework
T01
— Meat and Poultry Microbiology
Joshua Gurtler, University of Georgia and Marcos Sánchez, University
of Nebraska-Lincoln
The first four presentations, related to meat products, started with an overview
of microbiological risk assessment programs in Canada. Researchers from the
Ontario Ministry of Agriculture developed a program to evaluate microbiological
risks on raw beef in Ontario abattoirs. An industry speaker then presented data
regarding the performance standards of Clostridium perfringens in cured meat
products. The company provided additional information to explain the behavior
of this organism during several processes, including cooking, chilling and storage.
A microbial intervention presented was the use of hydrodynamic pressure processing
to reduce bacterial levels in ground beef with representative results. Finally,
a private company introduced equipment and supporting data on the use of wet-vacuum
procedures for surface testing of beef carcasses. The second segment of presentations
focused on broiler operations. Researchers from the University of Nebraska presented
microbial data to present a profile for broilers processed using air-chilling
processes instead of the conventional water immersion. Data presented included
farm and plant information. Additionally, a comparison between immersion and
air-chilled broilers was presented. Two USDA speakers also presented information
about the association of microbial contamination between the farm and the plant,
using the pathogens Campylobacter spp. and Salmonella spp. as references. New
information presented included the microbial quality of free-range chickens
compared to the conventional broiler. Speakers from Auburn University explained
the potential of bacteria isolated from deboning operations to inhibit the presence
of C. jejuni. Finally, a profile of yeasts, including Zygosaccharomyces bailii
was presented in connection with commercially processed broilers. A general
conclusion from the session was that there is a need to combine farm and plant
data and interventions to reduce bacterial levels in meat and poultry products,
to support the farm-to-table initiative.
T02
— Microbiological Methods
Ginny Moore, University of Wales Institute-Cardiff and Kelly
Stevens, North Carolina State University
This technical session presented at IAFP 2002 featured current research updates
in microbiological methods. Several presenters were part of the developing scientist
competition. A wide range of methods and innovations were presented, running
the gamut of methods used not only in microbiological work but also in food
safety related issues, including the detection of spinal cord tissue.
Several of the presentations in this session focused on traditional microbiological
methods such as microscopy and cultural procedures. The incorporation of molecular
techniques was also presented. Yashodhar Burgula started off the Microbiological
Methods technical session by presenting a conventional method with modification
to enhance the recovery of stressed Salmonella from cultured dairy products.
The use of TSA supplemented with ferric ammonium citrate and sodium thiosulfate
improved recovery of Salmonella and had the potential for better exposure assessment
for use in quantitative risk assessment. Walairut Chantarapanon presented research
utilizing direct microscopic observation to identify sites on chicken skin that
allow attachment and survival of Campylobacter jejuni. Geunwoo Park presented
a detection method for Shiga Toxin producing Escherichia coli. The method takes
advantage of glutamate decarboxylase genes and enzymes present only in E. coli.
Beth Ann Crozier-Dodson used a thin agar layer method utilizing selective media
to optimize recovery of air-borne microorganisms in dairy cattle facilities.
Jared Gailey presented the development of a valid sampling plan for the detection
and enumeration of Salmonella in pig pens. Lynette Kleman, from North Carolina
State University, presented a rapid sample preparation and associated detection
procedure for produce that yielded a 250 fold reduction in sample size and was
compatible with molecular methods such as PCR. The method presented was sensitive,
easy to use and inexpensive.
Eileen Cole, from Qualicon, presented
technical information on comparison of the new gel-free automated BAX system
with traditional culture methods. The automated BAX system is comprised of an
integrated thermocycler and detector. The system uses a fluorescent DNA intercalating
dye and melting curve analysis to ultimately yield comparable sensitivity and
specificity as cultural methods. R. P. Betts presented development data for
the detection of mold by the MicroFoss System. The procedure presented can detect
the presence of mold contamination after 72 hours of incubation. Maha Hajmeer
presented an overview of the detection of spinal cord tissue by use of two commercially
available immunological kits. Kit sensitivity, detection level and ease of use
were compared for the kits evaluated.
The use of surrogates (harmless
microorganisms with slightly higher heat resistance than the target pathogens)
would allow logistically easier and potentially safer testing of thermal processes
and CCP validation than the use of the pathogen itself. Research in this area
was presented by two authors. B. A. Annous described the use of a non-pathogenic
strain of E. coli for use as a surrogate
in place of E. coli O157:H7 in pilot
plant challenge studies. Jeffrey Kornacki described the use of Pediococcus
species NRRL B02354 as a thermal surrogate in place of Salmonella
and Listeria monocytogenes.
T03
— GMOs and Produce
Laura Bauermeister, University of Nebraska-Lincoln and
Joshua Gurtler, University of Georgia
In
the GMO session, many authors expressed general concern that there is a growing
need for education concerning GMOs. Cohn discussed the impact biotechnology has
had on the food service industry and concluded that to achieve consistency in
GMO labeling, the FDA should establish criteria for what constitutes a biotech
food in the marketplace and some sort of criteria for the voluntary labeling of
foods. Harlander was concerned with the labeling issues at the retail level,
indicating that there was a need for consumer education on GMOs. Blaine found
that when consumers were educated about Bt sweet corn, the GM corn outsold the
non-GM corn in that particular market. Gomes indicated that many education
initiatives concerning biotechnology have been implemented throughout the world;
however, there is no published work on the best way to distribute this
information. In this study, they found that it was best to develop materials
that are practical for people’s needs in each situation. Bruhn discussed the
attitudes of consumers towards GM foods, indicating that companies labeling
foods as “No GMO” will be facing increased difficulties with a
zero-tolerance policy, especially in those foods with a mix of many different
ingredients. The Produce Session covered a broader scope of topics. Isaacs
indicated that when a new outbreak occurs in a product, this offers an excellent
opportunity to study and reassess potential risks in processing of that product.
In this case, they studied the first outbreak of Salmonellosis
associated with nuts. Luedtke discussed some of the problems they
encountered as they were developing a HACCP-based farm management program and
how they were able to work with vegetable producers to develop a more manageable
program for the producers. Brashears indicated that the use of competitive
inhibition with certain LAB species shows promise in the control of pathogens
during the sprouting of alfalfa sprouts. Thomas showed the results of a survey
done of California sprout growers to determine compliance with the FDA
guidelines. Wade found that the removal of decayed or damaged tissues in
tomatoes during sorting, as well as minimal processing, may decrease the chance
of pathogen presence in raw tomatoes because of altered pH of the tissue, which
creates a favorable environment for some pathogens. Kniel found ozone and
hydrogen peroxide were effective treatments and may be an alternative to
pasteurization of fruit juices for controlling C.
parvum. Suslow found that the location of animal farms vs. produce farms
could be considered a risk when monitoring fecal indicators on some produce
farms. Many valuable studies were presented in this session.
T04
— Public Health and Outbreaks
Michelle Danyluk, University of Georgia and Marcos Sanchez, University
of Nebraska-Lincoln
R. Lee began this technical session with a talk about the Environmental Health
Network, which has collection sites in nine states. It is currently conducting
a project dealing with health concerns connected to restaurants, such as the
magnitude of unhealthy practices and the adherence to state and local food program
policy. M. T. Destro continued with an example of staphylococcal food poisoning
in Brazil. After attending a party, 180 people became sick; 16 food isolates
and 43 clinical isolates of Staphylococcus
were collected. Isolates were screened by phage typing, antibiotic resistant
profiles, enterotoxin testing and RAPD genotyping, and the outbreak, which was
linked to vegetables, chicken and pasta served, was found to be disseminated
by four of the food handlers. J. Farber then discussed the epidemiological typing
of Campylobacter isolates from clinical
and stock cultures by PFGE. No Campylobacter
isolates were found in 119 ready-to- eat foods sampled, or from 125 environ-mental
samples taken in restaurants. Dose response modeling of E.
coli O157 from food and waterborne outbreaks was addressed by N. J. C. Strachan.
Using Poisson dose response distribution and the eight data points that
exist from outbreaks, they suggest new E.
coli O157 lines, closer to those of Shigella
than to the animal model for E. coli
O157. P. M. Tanner analyzed US cross-contamination incidents in the food industry
and found 924 incidences, of which 33% led to illness or injury.
Of these, 70% were related to
microbial con-tamination and 30% to chemical contamination. The largest outbreak
involved a dairy in Chicago, and 5 states were affected by salmonellosis. Finally,
the implications of flies, pathogens and public health risks were discussed
by J. Buttler.
Hemolytic isolates were identified
by 16s rRNA analysis. Acinetobacter baumann,
Bacillus puilus, Enterobacter
sakazakii and Shigella flexneri were
identified for the first time. Other pathogens, such as E.
coli O157:H7 and Salmonella spp.,
were also identified, providing information about a new potential route for
contamination of foods.
>T05
— General Food Microbiology
Megha R. Gandhi, Rutgers University and Ethan Solomon, Rutgers
University
This
technical session, held on Wednesday morning, had presentations dealing with
various aspects of food safety. Presenters spoke about issues such as food
contamination by terrorists, and the threats involved, and a proposed
operational risk management systems approach to deal with it; and the
development of a food safety network to deliver food safety information to the
public and food safety in food manufacturing facilities and the financial losses
involved in product quality failures. Some presentations were on topics such as
microbial risk assessment of Salmonella
Typhimurium in processed postchill broilers, thermal inactivation of milkborne
organisms, and inactivation of foodborne viruses by high pressure processing. A
couple of speakers talked about the microbiological levels in warewash machines
used in food service establishments and water in vending machines.
T06
— Antimicrobials
Megha R. Gandhi, Rutgers University and Ethan Solomon,
Rutgers University
The
technical session “Antimicrobials,” held on Wednesday afternoon, focused on
antimicrobial treatments that can be used to deal with micro-biological food
safety problems in various foods and food processing environments. Presentations
provided valuable information on the use of acidified sodium chlorite to extend
the shelf life of produce and as an in-home antimicrobial spray, control of Clostridium
botulinum in RTE foods, and the use of ozone for decontamination in the food
industry. Other topics of interest were intervention strategies to reduce Escherichia
coli O157:H7 on beef cuts and trimmings, Listeria
monocytogenes contamination in a salmon smoke house and its control
(comparing two sanitizing methods), biofilms and their significance to the food
industry, and multiple antimicrobial resistance among Salmonella
isolates.
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