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AGBIO/FDSC 521: Food Defense
Biological Hazards and Controls – Ln 2 Lecture 4
Biological Hazards and Controls
Please note: This transcript was taken directly from the VoiceThread presentation
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Slide 1: Biological Hazards and Controls
This is AGBIO521, today were going to continue talking about HACCP and
biological hazards.
Slide 2: Guest Speaker
My name is Martin Bucknavage. I'm the senior food safety extension associate
here at Penn State University. I work with Dr. Catherine Cutter in the area of food
safety and food defense.
Slide 3: Foodborne Outbreaks
When we think about hazards that are normally associated with foods,
undoubtedly biological hazards have the biggest impact with regard to food-born
illness. I'd like to guess that most of you have seen one of the recent outbreaks
associated with biological hazards. Most recently we have the outbreak of E. coli
in Germany that was associated with sprouts. In this case there were over 3000
illnesses and over 30 deaths that were associated with sprouts that had been
contaminated with this particular strain of E. coli. Another case that had gained
national prominence was a salmonella case associated with peanut butter
produced by PCA in two plants, one in Texas and one in Georgia.
CDC defines a foodborne disease outbreak is “an occurrence of 2 or more cases
of the similar illness from the ingestion of a common food”. However it's
estimated that this is only a small fraction of foodborne illnesses cases reported
to the CDC. There are much larger number of cases that recalls sporadic cases.
These sporadic cases are cases that occur when there is a lapse in practice
either at home or in the food service staff establishment that maybe one person
becomes ill. These cases are often not reported back into the CDC.
Slide 4: Type of Foodborne Disease
In order to discuss biological hazards, it's important to differentiate between
infections and intoxications. In an infection, the pathogens are ingested with the
food and they multiply in the body causing illness. Salmonella is a good example
of an infection.
In an intoxication, the bacteria grow in a food, producing a toxin and then when
we consume the food along with the toxin, the toxin causes illness. Staph
enterotoxin and botulism (Clostridium botulinum) are two good examples of
intoxications.
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There's also a toxin-mediated infection. In this case, we consume a pathogen
that grows in our body and then as that bacteria grows, it produces a toxin. A
good example is E. coli 157:H7. It causes an infection when we consume the
organism, and as that organism is growing inside us it also produces a toxin. In
this case a toxin that affects our kidney function.
Slide 5: Factors Affecting Susceptibility
When we talk about food borne illnesses, itʼs important to discuss a personʼs
susceptibility, or the inability to prevent infection by an organism. There a lot of
things that impact that, such as a person who is advanced in age and their
immune system is on the decline or they could be young and their immune
system has not fully developed. Another important part of that is pregnancy.
When a woman is pregnant, thereʼs a certain level of immunosuppression that
goes on, and during that time sheʼs more susceptible to food borne illness. And
of course there are other things such as AIDS or when people are on cancer
medication that can also impact a personʼs susceptibility.
Slide 6: Type of Foodborne Disease
Now let's start talking about the types of biological agents. First we have bacteria.
They account for about half of the foodborne outbreaks that have occurred
between 2001 and 2004. They include a lot of bacteria that were probably
familiar with, organisms like salmonella, E. coli, Clostridium botulinum,
staphylococcus, and maybe some organisms were not as familiar with,
organisms like Yersinia, Bacillus cereus, and Clostridium perfringens.
Slide 7: Type of Foodborne Disease
There are also viruses. The two viruses that we will discuss are Norovirus and
hepatitis A. There are some other foodborne viruses, but these two account for
the vast majority of foodborne illness cases that occur [from visuses]. In terms of
parasites there are a number of parasites. Cryptosporidium, Cyclospora, Giardia,
Trichinella, Tacoplasma, and Anisakis. There are others, but these will be the
ones that we will discuss.
Slide 8: Factors Contributing to Foodborne Disease Outbreaks
What conditions lead to foodborne illness? Well generally it's going to be a lapse
in a procedure that we have. The product could be held that an improper storage
temperatures, [that is when] cold food is held too warm or hot food is held too
cold. The product is held in what is called the “temperature danger zone”.
Another is inadequate cooking, we don't bring the food up to the adequate
temperature. Poor personal hygiene includes people not washing their hands,
people coming to work with debris or soils on their clothing. Cross-contamination
is another factor. If we don't properly clean the surface after it's been used to
handle raw products, improper reheating, poor storage practices, we hold the
product in places that food is subject to contamination.
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Slide 9: Microbial Hazards: Characteristics and Controls
As we start to look at the biological hazards that can be associated with certain
foods, we want to look at the organisms themselves. Is the organism a spore
former like Clostridium botulinum that can survive a heat treatment? Is it an
organism like Salmonella can survive in a dry environment for an extended
period of time? What's the state of the microorganism? Is it in the stationary
phase of growth? Or are the cells injured? And this could impact the survivability
of that organism. What's the infectious dose? The infectious dose being how
much needs to be there to cause an infection. We look at organisms like
Norovirus or hepatitis A, they have a low infectious dose, that is, there does not
need to be a lot of viral particle there to cause illness.
Another thing that we have to do is look at the characteristic of the food. Does the
food have certain nutrition available for microbiological growth such as protein
carbohydrates? What is the acidity level? Of course products that are more
neutral in pH are going to be more apt to have bacteria growth. And as that pH
decreases, itʼs going to start to prevent bacterial growth. How is the product
stored? Is it stored in what is called the temperature danger zone from 41 to 135
Fahrenheit? And along with that how long is that product being held in that
temperature danger zone? What's the oxygen level? Is it a vacuum packaged
product that creates an anaerobic product that will allow growth of anaerobic
organisms like Clostridium botulinum.
And of course what's the moisture level? And the term that we use for moisture is
water activity, or the available moisture. As the water activity increases or there's
more moisture available, you're going to have more ability for microorganisms to
grow. When you think about a meat product or product like milk, they have very
very high water activities and so they're subject to have bacterial growth in them.
As the water activity drops, there's less moisture available for microorganisms to
grow. And so when we look at products like saltine crackers or we at look at
bread, weʼre not going to see bacterial growth. If anything weʼll see mold growth.
Slide 10: Microbial Hazards: Characteristics and Controls
The food microbiologist needs to look at each food and determine which
microorganisms can survive in a food or growing in the food. They have to look at
the antimicrobials that may naturally be in the food or may be added in the food
that could inhibit the growth or the survival of the organisms. They have to look at
a combination of factors associated with that food, something that we call the
hurdle effect. The hurdle effect factors is assault level, moisture level pH level,
may work together to inhibit bacterial growth.
Slide 11: Microbial Hazards: Characteristics and Controls
In the food supply chain there are a number of controls that prevent the
contamination of food to begin with. Some examples of these are the harvesting
of shellfish from approved waters, in that these waters have been tested to show
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that they donʼt contain toxigenic algae that shellfish can feed on. Another thing
that we have are good agricultural practices or GAPS, and these are procedures
that are used by farmers to prevent the contamination of fruits and vegetables.
In food operations there are practices that are used to prevent cross
contamination. Separation of raw and cooked foods - if you go to the counter in a
retail store youʼll see that cooked seafood is separated from raw seafood.
Another thing thatʼs done is the cleaning and sanitizing of shared surfaces. If we
have cutting boards or we have cook counters, those counters are cleaned and
sanitized before we start to handle ready to eat foods on them.
Slide 12: Microbial Hazards: Characteristics and Control
There are certain control measures that are in place that will destroy or remove
foodborne pathogens. You could have a heat treatment where food is heated to a
certain time and temperature to eliminate any type of pathogens, we could use
irradiation, freezing is often done for certain types of parasites especially in
certain types of seafood. The meat industry uses a lot of surface washes,
carcass washes, as a way to remove pathogens from the exterior surface of a
carcass. And there are a number of new technologies, high-pressure, pulsed
light, that are currently being developed and in some cases being used as a way
to destroy and remove pathogens from food products.
Slide 13: Microbial Hazards: Characteristics and Control
One of the terms that we use when weʼre talking about bacterial destruction is log
reduction. Log reduction stands for a tenfold or one decimal reduction or 90%
reduction in the number of recoverable bacteria in it food. We often look for a 5
log reduction, and this is a value for some food to be reduced by 10 to the 5th
power or by a factor of 100,000.
Slide 14: Microbial Hazards: Characteristics and Control
The next set of controls looks at preventing the growth of foodborne pathogens.
A number of these things such as freezing or refrigeration use temperature to a
limit or prevent bacterial growth. It's also important to use proper cooling after a
heating step to ensure that as the products cools it does not provide an
opportunity for bacterial growth, especially organisms like Clostridium perfringens
in meat that was just cooked.
Another thing that we use is hot holding. We see this in food service, food is held
at 135° or higher and this prevents bacterial growth, from organisms like
Staphylococcs aureus. Outside of temperature, we can look at the decreasing
pH. As a product drops below 4.6, it prevents bacteria especially Clostridium
botulinum, from growing. Another thing we can use as preservatives. A number
of preservatives like sodium nitrate prevent bacteria from growing in meat
products. Often times what we use is the hurdle effect, as we mentioned earlier
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we use a combination of these factors and these provides a synergistic effect in
preventing bacterial growth.
Slide 15: Bacteria Escherichia coli O157:H7
Next we are going to move on to each of the biological hazards. One of the 1st
that were going to talk about is E. coli O157:H7. This is a particularly devastating
strain of E. coli in that it causes both an infection and creates a toxin. And this
toxin can affect kidney function. Generally when somebody becomes infected,
they have diarrhea which progresses into bloody diarrhea. Along with that, this E.
coli strain produces a toxin that shuts down kidney function. So there is the
potential that somebody that is infected with this can have a loss of kidney
function, which could mean either dialysis for months or for years or it could be
death if not treated properly.
The source of this organism is the intestinal track of animals, primarily ruminants
such as cows. We see that transmission to food from fecal contamination. We
also see it with cross-contamination when people are handling raw meats along
with ready-to-eat food items or with things such as vegetables.
While this organism is destroyed by mild heat, it can survive in low-acid foods.
Weʼve seen this in outbreaks involving juice products over the past few years. In
order to control this organism is important to properly cook the food products.
Whether you're cooking hamburgers on the grill or different types of beef
products, it's important to cook them at the right temperature. Another thing we
want to do is prevent cross contamination from a surface that may have had raw
beef or raw meat product to a food product that is ready-to-eat. It's also important
to have proper refrigeration. You certainly don't want this organism growing to a
high number that may increase the chances of having cross-contamination.
Bacteria
Escherichia coli O157:H7
Disease
Infection/enterotoxigenic – severe cramping (abdominal
pain) and diarrhea which can progress to bloody. Hemolytic
uremic syndrome in immunocompromised.
Onset / duration
2 to 12 days / lasts over 8 days.
Source
Intestinal tract of animals and humans (carriers)
Transmission
Fecal contamination of food or water. Cross contamination.
Characteristics
Destroyed by mild heat (>140 F); survives in low acid foods;
grows at temperatures greater than 45 F.
Control
Proper cooking; prevent cross contamination; proper
refrigeration.
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Slide 16: E. Coli O157:H7
There have been a number of outbreaks involving O157:H7. In 1993, Jack-in-theBox was involved in an incident where hundreds of people became ill with E. coli
and also had a few deaths. This case led to E. coli being declared an adulterated
in ground beef. In 2006 we have the spinach outbreak were hundreds of people
became ill from eating tainted spinach. Spinach became contaminated due to its
proximity to cow pastures, most likely the cause being the irrigation of the
spinach with water where the cows were occupying.
Another big outbreak, more recent outbreak was the Topps frozen beef outbreak
in 2007. This led to a very large recall, 21.7 million pounds of meat product being
recalled. And really the issue here was that there was carryover of meat. Meat
came in that had E. coli contamination in it, this product was frozen, it was
shipped out across the country and it caused a number of illnesses. The primary
concern was the fact of using frozen patties, people don't often get the internal
temperature up to the right temperature, allowing E. coli to survive in and cause
infection. Another issue with Topps here is the fact that traceability became an
issue. The common term that we use is “slop back” and every day they would
hold product back to be blended into the next production day, which never leaves
a clean production date. In looking at traceability, this case here really points out
the need to have clean breaks and have clean lot codes that have product. When
we think about food defense and we think about controlling contamination within
an operation, it's so important to have those clean breaks either through
sanitation, through proper labeling, through the control of rework. That certainly
was not the case in this Topps outbreak, leading to such a large recall.
Slide 17: E. Coli O157:H7
The meat industry has gone a long way to help reduce the instance of E. coli in
meat. Looking at intervention strategies on a farm and before slaughter, trying to
reduce the in-housing feed and water through the use of antibiotics and vaccines,
probiotics through different types of chemicals, through managing the
transportations we don't get contamination from cow to cow during transportation
and also once the cows arrive at location where they're held in holding pens. And
making sure that the cows themselves are clean. Oftentimes cows will trample
through the mud and the dirt, they have E. coli kicked up onto their skin and by
keeping cattle clean, it helps to reduce the instances as well.
Slide 18: E. Coli O157:H7
Within the meat processing plants themselves, a number of intervention
strategies are also put in place. These things range from how the animals are
slaughtered, how they're eviscerated through how the carcasses themselves are
cleaned. Making sure the employees themselves are clean and don't carry the
cross-contamination, all of these things, all these different methods can not only
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impacting E. coli but they also impact other pathogens. So it's important to
recognize that there are a number of methodologies that are being used in meat
processing plants as well as other plants, to reduce the level of contamination,
especially on raw products such as beef carcasses.
Slide 19: E. Coli O157:H7
Another important step is once the meat is going to be ground, of course this is
where the E. coli on the exterior portion of the meat is then drawn into the internal
part during the grinding operation. So it's important, here, for those that grind
meat to have control measures in place as well. One of the things that we often
see is that the purchasing company will request from their suppliers a certificate
of analysis or a COA. In the COA basically provides some documentation that
some testing was done, analysis was done, onto the product to ensure that it was
free from E. coli. Of course is important to recognize a certificate of analysis will
only go so far. It's looking at one sample taken from or a set of samples taken,
and composited from a lot of beef.
Another thing that often occurs before grinding is some treatment of that trend
meet. Hot water, organic acids, a combination of treatments can be done on that
trim prior in the grinding process to help reduce the incident level of E. coli in that
product. And of course we can always go through and do microbiological testing
on a ground product as well. However, again, anytime we rely on testing we have
to recognize that were only taking small amounts of the larger quantity that's in
that lot.
Slide 20: E. Coli O157:H7
The government has taken a big step in working with the industry to reduce the
E. coli O157:H7 prevalence in meet. And in this particular case, working with the
USDA FSIS where they have increased the amount of testing and analysis of
trim, looking to verify the control of plants with regard to E. coli O517:H7. Testing
products, being able to conduct more rapid recalls, focusing on the areas where
contamination would be the biggest concern: in the slaughter and grinding
facilities. And then working with international suppliers to make sure that they
have the proper mitigation strategies in place.
Slide 21: E. Coli Non-O157:H7
In addition to E. coli O157:H7, there are some non-O157 strains that have gained
increased attention because they've also caused illness in individuals, causing
HUS. Most recently was the outbreak in Germany that was related to sprouts.
Where over 3000 people became ill with approximately 700 cases of HUS and
more than 30 died. In this particular case it was the O104:H4 strain that caused
illness. There are a number of these different strains, non-0157 strains that have
been identified and have caused illness and so right now the government
attention is looking at how best to control these different strains.
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Slide 22: Bacteria – Listeria monocytogenes
The next organism weʼre going to talk about is Listeria monocytogenes. This
foodborne pathogen has a higher mortality rate primarily in people that are
susceptible: higher risk populations such as older people, younger children, and
really where it has been most impactful is for women that are pregnant.
What happens is this organism, found in the environment and animals,
contaminates food processing facilities and it can grow to high numbers. One of
the hallmarks of this organism is its ability to grow at refrigeration temperatures.
So this organism grows at refrigeration temperatures in these facilities and even
though these facilities may have a heat treatment in place such as on a meat
product like a deli meat product, because this organism is in the post-process
environment, it can contaminate that product and then once it's shipped and held
at refrigeration temperatures for long periods of time, it continues to grow. Once
it's consumed by the individual, this organism leads to a blood infection or
septicemia which can lead to meningitis as well as the miscarriage and death of
the mother.
Facilities need to make sure that they have good control measures in place,
besides properly heat-treating their product. We also need to make sure that the
process environment is clean. So facilities will go to great lengths to ensure that
they have good sanitation measures in place but also to have measures in place
to monitor the environment to ensure that they don't have high levels, to ensure
that they don't have any levels, of Listeria within their processing environment.
Bacteria
Listeria monocytogenes
Disease
In susceptible, fever, nausea, vomiting, coma or
death. Abortion possible in pregnant woman.
Onset / duration
Few days to several weeks.
Source
Animals and the environment.
Transmission
Consumption of contaminated vegetables, dairy products,
RTE meats, and seafood.
Characteristics
Destroyed by heat (161 F for 15 sec); grows at refrigerated
temps (>31 F), salt tolerant, grows at pH >4.6.
Control
Proper heat treatment; low pH; proper temperature control;
inhibitors; prevent re-contamination.
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Slide 23: Listeria monocytogenes
One of the biggest issues we have with listeria is exposure in the post-lethality
environment. As an example, if we have deli meats, deli meats go through a cook
step. After the cook step, they cool down and are often times packaged. Itʼs in
this packaging step that we have concerns for listeria, because listeria can grow
in this cold environment, contaminant product, and then grow in that product
before the consumer buys it. So anytime we have any post-lethality exposure, we
want to make sure listeria is controlled within this environment so it doesnʼt
contaminant product.
Slide 24: Listeria monocytogenes
So these facilities with post-lethality exposed product must have control
measures in place to prevent the contamination of their product by Listeria
monocytogenes. These can be done through a HACCP plan or through
prerequisite plan such as sanitation.
Slide 25: Listeria monocytogenes
The USDA has established three different alternatives for facilities that do
produce post-lethality product that does have post lethality exposure. Alternative
1 includes a post-lethality treatment on the product where the product may be
heated in the package as well as the inclusion of an antimicrobial agent in the
formulation of that product to suppress the growth of Listeria during the shelf life
of that product. These products have the lowest risk in comparison to alternative
2 and alternative 3. In alternative 2, you do have one or the other. They could
have a post-lethality treatment or they could have the addition of an antimicrobial
agent. Finally there is alternative 3 where they require the use of good sanitation
measures to be in place only for the control of Listeria monocytogenes. Of the 3,
this has the highest risk and really focuses a lot of attention on control and
monitoring of the post-lethality environment.
Slide 26: Control Measures for Listeria monocytogenes
So there are some different procedures that companies can use to control
Listeria monocytogenes in the post-lethality environment. On the processing side,
they can look at post-packaging heat treatments where that product is perhaps
heated in a steam tunnel after it's been packaged or that product is irradiated.
The packaging itself may have the incorporation of different types of
antimicrobials and once that product is in the package, those antimicrobials then
seep into the surface of the product eliminating any the pathogens that may be
there.
Slide 27: Control Measures for Listeria monocytogenes
Another thing that they can use is to make different types of changes within the
formulation of the product. Fermenting the product, adding nitrites, changing the
water activity can prevent growth. They can also look at adding different types of
chemical agents or chemicals into the formulation of that product (organic acids
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or other different types of chemicals that prevent the growth of Listeria). Another
thing is to use live cultures or the use of bacteria sins, which are compounds that
have been isolated from cultures that have been shown to be antagonistic
towards Listeria monocytogenes.
Slide 28: Control Measures for Listeria monocytogenes
Within the post-process environment, there are some sanitizers that can be used.
Acidified sodium chlorite, Peroxyactic acic, ozone, and UV are types of chemicals
that are being used that have been shown to have a decent lethality against
Listeria monocytogenes.
Slide 29: Bacteria - Campylobacter
Campylobacter is one of the leading causes of sporadic diarrheal illness in the
United States. Generally what we see with this organism is an infection that leads
to abdominal pain, fever, and diarrhea. Diarrhea normally lasts up to 7 days and
it's often followed on with another syndrome called Guillain-Barré syndrome
which occurs 1 to 3 weeks after infection which basically mimics a severe arthritic
situation in the joints.
This organism is often found in poultry products and in fact, has a high
prevalence in poultry products. Somewhere between 30 and 40, up to 70% of
poultry may contain or may have this organism associated with it. The reason
that it causes sporadic diarrheal illness is because of mishandling of the poultry
that occurs in the home. So people who buy a turkey and don't handle it correctly,
this can lead to situations such as cross-contamination, on cutting boards on
knives or it also can be under cooking situations where the product may not be
brought to the proper temperature.
Some characteristics of this organism is that itʼs microaerophilic: which means it
needs to have a little bit of oxygen but not too much. However it is very sensitive
to heat and very sensitive to drying so if it is on a surface that dries out, it
normally perishes.
The best way of controlling this organism is by preventing the crosscontamination as well as preventing the organism from survival by properly
heating the product. The industry is going to great lengths to try to reduce the
prevalence of it on the surfaces of poultry through better cleaning conditions
within facilities as well looking at different types of treatments is processing
facilities themselves.
Bacteria
Campylobacter
Disease
Infection – Abdominal pain, fever, diarrhea (profuse, and
sometimes bloody). LT Guillain-Barré Syndrome
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Onset / duration
2 days / lasts up to 7 days. Guillain-Barré Syndrome 1 to 3
weeks after infection.
Source
Intestinal tract of warm-blooded animals; most common
sources: raw milk and poultry.
Transmission
Direct contact with animals or through contaminated water,
milk or poultry; cross contamination.
Characteristics
Microaerophilic; sensitive to heat and drying.
Control
Chlorination of water; pasteurization of milk; proper cooking
of meat; prevent cross contamination; desiccation by air
chilling.
Slide 30: Campylobacter
So while the industry has reduced the prevalence of Campylobacter resulting in a
decline in the number of cases of Campylobacter infection, it still remains one of
the primary causes of sporadic diarrheal illness in the United States. So the
USDA continues to work with the facilities in trying to look at how it can be
reduced even lower.
Slide 31: Bacteria – Clostridium botulinum
The pathogenicity of Clostridium botulinum is based on the fact that produces
one of the strongest toxins known to man. This toxin is a neurotoxin and when
ingested, the neurotoxin affects the nervous system. Initially we see blurred
vision, dry mouth, difficulty in swallowing, and later we see paralysis of the
respiratory muscles. So what happens is that death can often occur if not treated
due to the fact that somebody suffocates because of inability to breathe.
The organism found throughout the environment contaminates product that's
normally heat-treated. So if we think of home-canned foods that are improperly
heat treated, this organism survives that heat treatment and then if the conditions
are ripe for growth, primarily having a pH above 4.6 and having sufficient
moisture there, the organism grows and produces a toxin. When somebody
consumes this food product with the toxin in there, they suffer the neurotoxin
getting into their blood stream and shutting down the nervous system.
In order to control this organism, it is important for companies to manage their
products properly. Making sure that they have the right heating processes in
place, making sure that they do have pH adjustments to lower the pH to a point
where the product is not susceptible to growth by Clostridium botulinum. They
have the measures in place to do that. For those products that are solely
refrigerated, it's important that they are in kept in refrigeration.
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Bacteria
Clostridium botulinum
Disease
Intoxication – blurred vision, dry mouth, difficulty swallowing,
paralysis of respiratory muscles
Onset / duration
12 to 36 hrs / lasts months, depending on severity.
Source
Soil, marine sediment, intestinal tract of animals; assumed
to be in all foods
Transmission
Spores germinate in food, usually previously cooked, and
produce toxin.
Characteristics
Anaerobe; heat resistant spore; low temperature growth (for
non-proteolytic); pH minimum 4.6; Aw minimum 0.92.
Control
Retort to destroy spores; low pH; low Aw; proper cooling.
Slide 32: Bacteria - Clostridium perfringens
Clostridium perfringens is another spore-forming organism just like Clostridium
botulinum. And we see this in heat-treated products, products like stews or
soups, the organism comes in on the ingredients and because of the spore
former it's able to survive as he treatments such as heating the stew or cooking a
ready-to-eat deli meat. And that those products are not properly cooled
afterwards and theyʼre held at an elevated temperature, this organism will grow to
high numbers and then when consumed those organisms get into the person's
intestinal tract and cause illness characterized by abdominal pain, diarrhea, and
nausea. So it's important when working with these different types of food
products is to ensure that they have proper heating and that also along with that
is to have proper cooling of those products.
Bacteria
Clostridium perfringens
Disease
Infection/Intoxication – abdominal pain, diarrhea, and
nausea. (No fever).
Onset / duration
6 to 24 hours / lasts 24 hours.
Source
Soil, intestinal tract of animals; Common in vegetables and
dehydrated foods.
Transmission
Spores germinated in mishandled, cooked foods; cells are
consumed, then grow / produce toxin in gut.
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Characteristics
Anaerobe; heat resistant spores survive normal cooking;
high growth rate occurs at 110 to 113 F; grows at
temperatures as high as 120 F.
Control
Proper heating and cooling of cooked, perishable foods.
Slide 33: Bacteria - Salmonella
One of the leading causes of bacterial foodborne illness in the United States is
salmonella. The CDC has reported that while other bacterial pathogens have
been on the decline, in terms of causing foodborne illness, cases of salmonella
has been on the increase.
One of the reasons for that is the fact that Salmonella is prevalent throughout the
environment - it's carried by number of animals including farm animals, birds, and
reptiles. Another thing is that salmonella can survive in a dry state for an
extended period of time. Along with that, it has a very low infectious dose, it only
takes 100 or so cells to cause infection. And because of this, it's easy to see that
small lapses in good manufacturing practices can lead to salmonella
contamination.
A good example of that is the Peter Pan peanut butter outbreak a few years
back. In this case, a leaky roof allowed Salmonella to gain access into the facility
and once they are there, the organism was able to contaminate the product on
the process side and the post process side of the heat treatment. Once there, the
organisms survived in that peanut butter as it was shipped across the country
and this resulted in over 500 cases of foodborne illness. There have been
another of other issues as well. We have the salsa outbreak a few years back,
where how jalapeno peppers were contaminated with salmonella. These peppers
were often times mixed with tomatoes to make salsa and then this product was
served, it caused a great number of cases of Salmonella. Other cases that have
been involved with salmonella include pet food, snack foods, and bean sprouts.
In order to control salmonella, it's important for companies to have proper
cooking procedures in place. Another thing is that itʼs very important is to prevent
re-contamination. After the product has been cooked or after it has been treated
it's important to prevent cross contamination onto those products, as well as to
prevent cross-contamination onto any ready-to-eat products especially fruits and
vegetables. Another thing that's important is to have proper hygiene practices
practiced by food handlers. Hand washing, making sure employees change their
clothing so they don't bring contamination into the processing facility.
Bacteria
Salmonella
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Disease
Headache, abdominal pain, mild fever, nausea and diarrhea.
Arthritic symptoms can occur one to three weeks later.
Onset / duration
6 to 72 hours / 3 days.
Source
Intestinal tract of animals and humans.
Transmission
Ingestion of organism in contaminated food (raw,
undercooked, or cross contaminated). Low infective dose
100 to 1000 cells.
Characteristics
Destroyed by mild heat (>140 F); grows at temperatures of
41.4 F to 116 F; survives in frozen or dried state.
Control
Proper cooking; avoid recontamination; low pH; proper
hygiene by food handlers.
Slide 34: Staphylococcus aureus
Staphylococcus aureus causes foodborne illness through intoxication. The
organism contaminates food and grows the high number and as it grows it
produces a toxin. When the food is consumed along with the top Senate can
cause a severe nausea, cramps, and vomiting. And this can be seen 1 to 6 hours
after consumption and can last a day longer.
The organism is found throughout the environment but has a high prevelence on
the skin of animals and in humans. Especially we see it in hair and in people's
nasal passages as well as on open sores and boils. While the organism is
destroyed by mild heat, the toxin is heat-stable. So once the food is contaminated
and the organism grows and produces toxin, any treatment of heat after that will
destroy the organism but not the toxin.
We see this organism associated with outbreaks in protein based salads. This is
the organism we often associate with people going on picnics. They take to tuna
salad or chicken salad and the organism grows on those protein products in the
salads. It grows to high numbers where the product is temperature abused, and
when that food is consumed then we have the resulting illness.
In order to control this organism it's important that people practice good hygiene,
making sure that they wash their hands and wear gloves when theyʼre handling
food, especially ready-to-eat food items. Another thing that's important to do is
when people have boils or sores on their hands, either that they don't work with
food for those boils or sores are properly covered through bandaging and
wearing gloves. Another thing that's important to do this for food products to be
held at the proper temperature. We either want to hold foods hot, at temperatures
greater than 135 or hold those foods cold at temperatures lower than 40.
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AGBIO/FDSC 521: Food Defense
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Bacteria
Staphylococcus aureus
Disease
Intoxication – Severe nausea, cramps, and vomiting.
Onset / duration
1 to 6 hrs / 1 to 2 days.
Source
Found in in air, dust, sewage, water milk, food, equipment,
animals and humans: skin, hair, nose, throat, open sores,
boils, saliva
Transmission
Organism grows in contaminated food and produces toxin,
which is ingested.
Characteristics
Organism destroyed by mild heat (>140 F), however toxin is
heat stable. Grows at temperatures of 45 F to 118 F; grows
in low Aw (0.83); wide pH range (4 to 10); resistant to high
salt (15%).
Control
Proper hygiene; proper hot and cold holding; exclusion of
workers with boils and sores.
Slide 35: Bacteria - Vibrio parahaemolyticus
Vibrio parahaemolyticus is another organism that causes foodborne illness and
primarily comes through the consumption of raw or undercooked seafood,
especially clams or oysters. So in order to prevent illness from this organism itʼs
important that we hold raw seafood at the proper temperature and that we
properly cook it. And then we also want to prevent any type of crosscontamination.
Bacteria
Vibrio parahaemolyticus
Disease
Diarrhea, abdominal cramps, nausea, headache, and rarely
fever.
Onset / duration
4 to 96 hours / 3 days.
Source
Marine sources and seafood.
Transmission
Consumption of raw, under processed or re-contaminated
seafood (primarily molluscan or crustacean shellfish).
Characteristics
Destroyed by mild heat (>140 F); grows at temperatures of
41 F to 109 F; grows in 0.5 to 10% NaCl.
Control
Proper cold holding of raw seafood (<41 F); proper cooking;
avoid cross contamination.
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Slide 36: Virus - Hepatitis A
Now we will discuss foodborne illness due to viruses. The first of the viruses that
will discuss is hepatitis A. Hepatitis A contaminates the food through the
exposure by an infected food worker. Once the food is contaminated and the
person is infected through the consumption of the contaminated food, it can take
15 to 50 days to see the symptoms of illness. These symptoms include fever,
malaise, but most importantly jaundice, and this is when hepatitis A is most
dangerous. Jaundice is caused by a loss of liver function in the affected
individual.
There've been a number of cases of hepatitis A contamination, but most of these
have been in food service operations were an infected food worker has handled
food for an extended period of time, exposing large numbers of people to the
virus.
In order to control this virus, it's important that workers practice proper employee
hygiene – especially making sure that they wash their hands and wear gloves.
Another thing that is important to do in an operation is to exclude ill food handlers
from the operation. So if somebody does have jaundice, when they do have a
fever, it's important to prevent them from working with food. The virus is subject
to heat treatments and so is important that foods are properly cooked and it's
also important that if we are consuming shellfish, they are taken from approved
shellfish areas.
Virus
Disease
Onset / duration
Hepatitis A
Infection - Fever, malaise, nausea, abdominal discomfort,
followed by jaundice; loss of liver function can occur.
15 to 50 days / lasting seven days until onset of jaundice;
shed virus 10 to 15 days before symptoms appear.
Source
Intestinal tract of humans.
Transmission
Human to human / fecal-oral route. Contaminated water and
food.
Characteristics
Heat sensitive (185 F); resistant to acid, freezing, and
drying; inactivated by oxidizing agents.
Control
Proper employee hygiene; exclusion of ill food handlers;
heat treatment; vaccination; approved shellfish harvest
areas.
Slide 37: Virus - Norovirus
The other virus that we will discuss is norovirus. Norovirus causes a large
percentage of the foodborne illness cases here in the United States. We often
16 AGBIO/FDSC 521: Food Defense
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consider Norovirus the “cruise ship virus”. That is when somebody is sick, they
get on board a cruise ship, before you know a large percentage of the people on
board have come down with Norovirus. And the reason for that is the fact that
when people are ill, one of the symptoms that they have is projectile vomiting.
When somebody has projectile vomiting, it exposes a number of people to the
virus, either through aerosolization of the virus or through direct contact with the
material. Another thing that's important about norovirus is that it has a low
infectious dose. There doesn't need to be a lot of particle to be there for
somebody to become infected.
In order to prevent norovirus infection it's important that food handlers practice
proper personal hygiene. And that they make sure that they wash their hands, as
well as wearing gloves when handling ready-to-eat food items. Another very
important thing that companies need to do is to exclude ill food handlers from
working with food. So if somebody is sick, especially if somebody is vomiting,
they should not be working in or around food.
Virus
Disease
Onset / duration
Norovirus
Infection – Acute onset vomiting, watery diarrhea, cramps;
occasional fever, headache.
24 to 48 hours / lasting 1 to 2 days. Shedding of virus can
occur for several days after symptoms.
Source
Intestinal tract of humans.
Transmission
Human to human / fecal-oral route; contaminated oysters;
virus contaminated surfaces; aerosolized vomit particles.
Characteristics
Heat sensitive (>140 F); low infective dose (100 particles).
Control
Proper employee hygiene (good hand washing key); heat
treatment; exclusion of ill food handlers; approved shellfish
harvest.
Slide 38: Parasite - Cryptosporidium
There are a number of parasites that can cause foodborne illness. Most of these
result only in sporadic cases. However there are some such as Cryptosporidium
parvum that can cause larger outbreaks. In the case of Cryptosporidium parvum,
we often see this with infected water sources. People consume the water that
has the parasite in there and this leads to severe diarrhea, nausea, and cramps.
It's especially harmful to those who are suffering from some immunological
disorder.
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AGBIO/FDSC 521: Food Defense
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In order to prevent large outbreaks from parasites, it's especially important to use
good water. And not use water that may have been contaminated, especially
when water is on the boil advisory due to some mishap at the water treatment
facilities. Another thing that is important to do is to practice personal hygiene,
when somebody is infected they can contaminate food through improper hand
washing.
Parasite
Cryptosporidium parvum
Disease
Infection – Severe watery diarrhea, nausea, cramps, lowgrade fever.
Onset / duration
1 to 2 days / lasting 2 days to 2 weeks. (May be
asymptomatic).
Source
Intestinal tract of cattle.
Transmission
Contaminated drinking water; food contaminated by ill food
handlers.
Characteristics
Single cell protozoa; heat sensitive (161 F for 5 sec); killed
by freezing (-28.8 F for 24 hrs).
Control
Use of potable water; proper employee hygiene; and heat
treatment.
Slide 39: Prion - BSE: Bovine spongiform encephalopathy
Next we'll briefly mention BSE. BSE is a progressive and fatal neurological
disease of cattle and this may be related to a similar type of disease in humans.
The disease is caused by a prion and it's transmitted into cattle from the
consumption of infected brain and spinal cord material that may be used in feed.
The US government has gone to great lengths to prevent BSE from entering into
the US food chain. A few of the things that they've done is prohibited the use of
these types of materials, brain and spinal cord tissue, from being used in feed for
ruminants such as cows. Another thing that they've done this to have an active
surveillance system in place to prevent any cattle from entering into the United
States that may have symptoms of this disease.
Prion
BSE – Bovine spongiform encephalopathy
Disease
Progressive and fatal neurological disease of cattle may be
related to CJD disease in humans.
Onset / duration
In cattle, 4 to 6 years to onset, period of deterioration is 2
wks to 6 months.
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AGBIO/FDSC 521: Food Defense
Source
Transmission
Characteristics
Control
Biological Hazards and Controls – Ln 2 Lecture 4
Infected brain and spinal cord tissue.
Animals contract disease from consuming feed containing
prion.
Extremely resistant to heat and normal sterilization
processes.
Prevent importation of high-risk animals and products.
Prohibit feeding of mammalian protein to ruminants.
Surveillance and quarantine suspected infected animals.
Slide 40: References and Additional Reading
We have covered the majority of pathogens associated with food. There are a
number of other pathogens that can be followed up on the references attached
here.
FDA: Bad Bug Book: Introduction Foodborne Pathogenic Microorganisms and
Natural Toxins Handbook http://www.fda.gov/food/foodsafety/foodborneillness/foodborneillnessfoodbornep
athogensnaturaltoxins/badbugbook/default.htm
CDC: Estimates of Foodborne Illness in the United States http://www.cdc.gov/foodborneburden/index.html
CDC: Food Safety Page - http://www.cdc.gov/foodsafety/
Slide 41: References and Additional Reading
These references will also indicate some of the different control measures that
are put in place by food manufacturers as well as in food service and retail
companies to prevent foodborne illness from occurring.
FDA: Food Safety Page - http://www.fda.gov/food/foodsafety/default.htm
USDA: Food Safety and Inspection - http://www.fsis.usda.gov/
Food Safety: A food safety portal - http://www.foodsafety.gov/
Slide 42: References and Additional Reading
Finally, here are two texts that go into greater detail on foodborne pathogens and
the different foods that they can be associated with.
Modern Food Microbiology (Food Science Text Series) by James M. Jay, Martin
J. Loessner and David A. Golden (Feb 10, 2005)
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AGBIO/FDSC 521: Food Defense
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Microorganisms in Foods 6: Microbial Ecology of Food Commodities (v. 6) by
International Commission on Microbiological Specifications of Foods (ICMSF)
(Jul 1, 2005)
Slide 43: Points to Ponder…
Now as part of your class participation I'd like to have some questions. The first
question is “are some biological hazards more common than others?” You can
think about this in terms of different newspaper reports regarding foodborne
outbreaks and food recalls.
Slide 44: Points to Ponder…
“Are some biological hazards more severe than others?” Think of this in terms of
ones that may cause more severe illness or ones that have a higher mortality
rate.
Slide 45: Points to Ponder…
Thinking about some foods that you normally consume: “what type of biological
hazards would probably have been associated with those types of foods?” Either
ones that may have already been removed through either your processes that
you do in your own kitchen or processes that have may have come upstream
from the manufacturer or through the farmer.
Slide 46: Points to Ponder…
Taking the last question one step further: “how were the biological hazards
controlled and the foods that you consumed?” What type of processes were put
in place either by you or by the manufacturer in order to control the certain types
of hazards.
Slide 47: Points to Ponder…
If our food safety systems are so good, “why do we continue to have outbreaks?”
Slide 48: Points to Ponder…
“Do you think the food reporting systems that aren't replaced by CDC threat the
states have changed how we've looked at foodborne outbreaks?”
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