June
2007
Microorganisms
That Make Us Worry
By Joyce Wilkins, MS, RD
Today’s Dietitian
Vol. 9 No. 6 P. 10
CDR Learning Codes: 2000, 2080, 4000,
4070, 8000, 8040; Level 2
Recent headlines about chemically contaminated
pet food have temporarily deflected focus from other food safety
issues. But pathogens have a way of remaining in the headlines,
and there will surely be more incidents to soon dissect and
discuss. People notice headlines and want to know how their
food is affected and what the foodservice industry is doing
about it. Whether your business involves an institutional or
retail setting, this information is vital.
In this article, we will look at how three pathogenic
organisms—one familiar and deadly, one relatively new
on the scene, and one that is currently just a threat—affect
the food industry. We’ll offer some practical suggestions
on preparedness and take a look at “superbugs” in
general.
E. coli
First, the familiar and deadly Escherichia coli (E. coli) 157.
Last fall, this pathogen contaminated raw spinach. Roughly 200
people were affected (11% were children under the age of 5).
More than one half of those affected were hospitalized, and
three people—one child and two older adults—died.
Another raw food—lettuce—was cited
in an outbreak involving Taco Bell restaurants in New Jersey,
New York, Pennsylvania, Delaware, and South Carolina. The Centers
for Disease Control and Prevention (CDC) announced in December
2006 that 71 people had become ill with E. coli infections.
Of the 48 people hospitalized with confirmed cases of E. coli,
eight developed hemolytic uremic syndrome (HUS).1
E. coli is found in all animal and human digestive
tracts, where it inhibits the development of more pathogenic
bacteria. Bacteria are good at acquiring genetic information
from other sources. At the time of the development of the O157:H7
strain, E. coli became infected with a bacterial virus that
had the ability to insert its DNA into the bacteria and continue
to replicate in daughter cells. This became the far more virulent
strain O157:H7.
The O157:H7 strain is an enterohemorrhagic E.
coli (EHEC) that causes intestinal bleeding. The genetic information
in this organism contains programming to produce a protein that
causes severe damage to intestinal epithelial cells. Once under
siege, the victim loses water and electrolytes, and the blood
vessels are so damaged that bleeding becomes hemorrhagic. This
condition is particularly dangerous to susceptible population
groups: children, elders, and immunocompromised individuals.
In some cases, this progresses to the kidneys, causing HUS—which
can cause permanent kidney damage. Most deaths are from HUS.2
As people strive for healthier diets, raw salads
will likely be a more frequent choice. But the spinach case
illustrates that safety may be harder to achieve when a foodstuff
is not processed.
Growing conditions are harder to control than
conditions in a factory or processing plant. A flock of birds
may pass through, leaving contaminants in its wake, and no one
will notice. The 2006 spinach outbreak originated in California’s
Salinas Valley, and backtracking identified four fields as possible
sources of the contaminated greens. The outbreak strain was
finally isolated and determined to have come from two sources:
cattle fields near the implicated spinach fields and a wild
boar that had been spotted and finally killed in one of the
fields.
Sometimes, we fail to realize just how vulnerable
fresh produce is. Bacteria are found in the soil where the food
is grown, in the water it is irrigated with, in the feces and
on the hands of those who harvest and handle it, in animals
that pass through and over the fields and leave their waste,
in pests that eat it or live on it, and in containers that hold
it during transit to processing. Even if carefully washed, produce
will carry bacteria. Chemical and thermal inactivation of the
pathogens is difficult due to the product’s delicate nature.
“We must face the reality that we live
in a microbial ocean,” says Sam Beattie, an assistant
professor and food safety extension specialist at Iowa State
University, who urges consumers to remember that processing
can’t eliminate bacteria in fresh foods.3
If the best we can do isn’t 100% effective,
what can we do? If we can’t prevent, we can minimize impact.
The most important reminder for the foodservice manager is to
stay tuned to the news when outbreaks emerge and product codes
are identified—the media is prompt to report brand names,
codes, and suspected distribution areas. A good relationship
with vendors is important as well, but we cannot assume that
our vendors are protecting us.
For example, a well-known restaurant was faced
with an outbreak of Salmonella enteritidis, verified by medical
examination and health department investigation. Perplexed by
this because their recipes specified pasteurized eggs, they
were embarrassed when it was discovered that their vendor was
providing unpasteurized eggs. Had it been diligent, the restaurant
would have discovered the less-than-optimum conditions under
which this vendor operated, thus alerting them to the danger
of doing business with them.
What we can control, we must control. At staff
training sessions, it is always wise to repeat the following:
• Pay special attention to highly susceptible
populations.
• Wash all produce, even if prewashed.
• Sanitize surfaces.
• Wash hands frequently.
Norovirus
Next, a relatively new-in-the-news pathogen, the Norovirus.
Noroviruses consist of several virus groups first named after
the places where outbreaks occurred. The first identified outbreak
occurred in 1968 in Norwalk, Ohio—hence the name Norwalk
virus.
This intestinal virus causes nausea, vomiting,
and diarrhea, usually lasting one to three days. Outbreaks of
Norovirus gastroenteritis have taken place in restaurants, cruise
ships, nursing homes, hospitals, schools, banquet halls, summer
camps, and homes.
Norovirus gastroenteritis is often reported
during winter as “stomach flu.” As its identification
becomes more common, it is considered the most common cause
of gastroenteritis in the United States, superseded only by
the common cold as a reported viral illness.4,5
Microscopically, the Norovirus is surrounded
by a protein ball. The virus’s genetic material is transferred
to the human intestinal cell as the ball attaches itself to
the stomach lining. Here, it produces more copies of itself,
killing the human cell and releasing more virus cells to attach
to still more of the intestinal lining.6
Gastrointestinal symptoms can occur within 18
hours of infection and persist for 48 hours. Those infected
may spread the virus after the abatement of the symptoms; some
people who show no symptoms may still be carriers.7
There are several characteristics of the Norovirus
that make controlling it a challenge. It is highly contagious;
it spreads through food and water; it survives on surfaces and
may travel through the air; and it is resistant to many disinfectants.
Norovirus cells are highly persistent and often defy common
sanitary principles. Fewer than 100 are needed to cause infection.8
The Norovirus is shed in large numbers in the vomit and stool
of infected individuals. An infected foodhandler can spread
the Norovirus by touching feces or vomitus and carrying the
cells to work surfaces, utensils, etc.
Thus, the challenge to the foodservice and housekeeping
industries is to maintain excellent personal hygiene and facility
cleanliness. The fact that the virus may be airborne compounds
the problem, as a client or patient who vomits in a dining room
could spew small droplets through the air. In addition, people
should not have access to a common food source, such as a buffet
or basket of rolls. It may be advisable in an institutional
setting to close the dining room and serve residents in their
rooms. Employees may have to be sent home. (A worker must be
clear of symptoms for 72 hours before returning to work.) Instruct
your staff to do the following:
• Report all intestinal illness to the
person in charge.
• Thoroughly wash all fruits and vegetables
and sanitize work surfaces.
• Wash hands frequently and thoroughly.
Stress that this protects them, as well as the customer.
Avian Flu
Currently, human infections with the “bird flu”
(Avian Influenza A [strain H5N1]) have been rare, with roughly
200 cases reported since 2004. Most of these cases are thought
to have originated from consuming contaminated poultry. Though
rare, there have been isolated reports of human-to-human transmission
of the virus. This is a disturbing possibility, as a pandemic
would occur if the virus, which mutates rapidly, develops the
ability to spread between humans. The 1918 influenza epidemic
killed from 50 million to 100 million people worldwide at a
time when transportation was difficult and travel was much less
common.
Today, the potential death toll would be staggering.
Symptoms of avian influenza infection range from typical flulike
symptoms to eye infections and respiratory distress, including
pneumonia, with severe life-threatening complications.9 The
following is a historical summary of bird flu from a report
from the Canadian Broadcasting Corporation:
The first reported deaths were in 1997 in Hong
Kong, where 18 people were stricken with severe respiratory
disease—six of them fatally—concurrently with an
epidemic of avian influenza in the poultry population. More
than 1.5 million birds were destroyed in three days, which may
have averted a pandemic. Similar poultry euthanasia in Vietnam
(2004) was concurrent with eight new human cases, six of them
fatal. Health officials ordered the culling of millions of birds,
but the threat continues.
In 2005, an ominous development—possible
human-to-human transmission—was reported. A man and his
two daughters in Indonesia died of H5N1, although none of them
worked around poultry. In October 2005, H5N1 was confirmed to
have spread to fowl in Romania and Turkey. Days later, a bird
on the Greek island Oinousses was found to have avian flu, though
officials hadn’t immediately identified the strain.
By March 2006, 97 people in Vietnam, Cambodia,
Thailand, China, Indonesia, Turkey, and Iraq had died from the
disease.
That month, seven people in Azerbaijan were
diagnosed with H5N1. Five died, raising the number of humans
killed by avian flu to 103 worldwide. Six of the Azerbaijan
cases were from the southeastern part of the country. According
to WHO [the World Health Organization], one possible source
of the infection was the carcasses of dead swans found in the
region—residents used the dead birds as a source of feathers.
There were 161 deaths in 2006 out of 267 confirmed
cases, according to the agency’s data, bringing the death
rate to 70%. It was 60% in each of the previous three years.
The Western Hemisphere was soon affected as
well: In November 2005, the H5 strain hit Canada. Two wild ducks
tested positive for H5N1 virus. The virus was also found in
a commercial duck on a farm in Chilliwack, British Columbia.
Another case was reported on Prince Edward Island in June 2006.10
In 2007, WHO issued a warning about bird flu:
As long as the virus continues to circulate among birds, the
threat of a human pandemic will persist. The agency said the
world is still years away from effectively controlling the illness
in the agricultural sector. It was also noted that 2006 was
the worst year yet for human fatalities of bird flu. A map,
available at www.pandemicflu.gov/#map, provides information
on the extent of this condition worldwide.
Typically, flu viruses are species specific.
In this case, the bird flu attacks only birds. Due to the activity
in southeast Asia, however, authorities are becoming increasingly
concerned about a potential mutation or recombination with a
human virus that may allow it to spread rapidly. Currently,
the human receptors appear to be buried deep in the lungs as
opposed to the nose or throat. Should the location of these
receptors change, spreading between humans would be far more
likely.11
As a result of repeated human infections and
given the highly virulent nature of this virus, the potential
of a pandemic similar to that seen in 1918 is entirely possible.
If the virus mutates to the point of passing
from human to human, it will likely spread with stunning speed.
This will be a pandemic of epic proportions. Some of the suggested
effects in this event include the following:
• People will resist leaving their homes,
hence fewer customers and employees.
• Grocery store visits will be less frequent
and bigger in size.
• Poultry consumption will plummet.
• Restaurant business will evaporate.
• Healthcare institutions will see increased
demand with limited and deficient resources.
• Companies will learn to operate with
significant staff shortages.12
As a result, authorities are actively educating
food producers, food safety personnel, and the general population
about measures to prevent or control this pathogen.
Although the virus has been found in the muscle
and eggs of infected poultry, there has been no reported incidence
of human infection as a result of eating cooked product. It
is prudent, however, to refrain from contact with raw carcasses,
such as those in open air markets, in areas where the virus
has been identified. The virus is inactivated by chemicals effective
against Salmonella and is destroyed by cooking. Refrigeration
and freezing have little effect on the organism.13
Procedures for foodservice personnel to have
in place are as follows:
• To the extent possible, negotiate with
vendors to provide appropriate commitments.
• Develop communication pathways with
local health authorities.
• Have an emergency call list of staff
willing to work.
• Clearly identify essential and nonessential
aspects of the company’s operation. Have a plan to “shift
resources.”
• Consider cross-training staff members.
• All food operations that will continue
to provide food must have an emergency menu in place with the
product sources identified.
The “Superbugs”
In January, several children became ill at a sleep-away camp
in Ramona, Calif. Apparently weakened by this illness, one 12-year-old
contracted methicillin-resistant Staphylococcus aureus (MRSA).
Unable to stop the spread of this powerful bacteria, medical
personnel watched helplessly as the child died a few weeks later.14
The rise of “superbugs,” those pathogens
that defy modern antibiotic treatment, poses a significant threat
to our expectation of modern medicine. In fact, according to
the Mayo Clinic, drug resistance may have contributed to the
58% rise in infectious disease deaths among Americans between
1980 and 1992. While this is not a new phenomenon (resistance
began almost as soon as antibiotics were developed), what is
different now, according to the CDC, is that this is no longer
a problem isolated to a specific bug. In fact, virtually all
pathogens important to humans have developed some resistance.15
Of course, overuse of antibiotics is the most
cited problem. It has been estimated that 25% to 40% of hospitalized
patients are treated with these drugs. The overuse is augmented
when the prevalence of antibiotics in the cattle industry is
included. It is estimated that 75% of the antibiotics used in
this country are used in animals, usually for the purpose of
increasing yield. An executive summary by the FDA states: “A
recent draft risk assessment examining the human health impact
of antimicrobials used in food-producing animals demonstrated
quantitatively that resistance development in food-producing
animals does impact on human health.”16
The risk is greatest in hospitals, nursing homes,
and other locations where immune systems may already be stressed.
While the risk is not great for persons in the community, incidents
such as the child cited previously show the possibility of the
dangers. This virulent strain of MRSA affects groups of people
in close physical contact: prisoners, those in day care centers,
and athletes on sports teams.
For example, two NFL players were hospitalized
with MRSA in 2006. The use of artificial turf creates the potential
for cuts since this surface acts more like a rug than grass,
producing abrasions that would not happen on a natural surface.
As with any skin break, cuts from this type of athletic event
offer the opportunity for bacteria to enter a person’s
body.17
While there is no specific list of superbugs,
the following are often cited as falling into this category:
• MRSA: This bacterium, which is the largest
cause of patient infections in U.S. hospitals, can infect burns,
skin, and surgical wounds. The CDC monitored more than 1,200
intensive care units from 1992 to 2003 and found that the number
of Staphylococcus aureus isolates that were multiresistant increased
from 36% to 64% by 2003. Despite the use of vigorous attempts
at eradication over the years, MRSA continues to be the major
health-associated pathogen in acute care institutions.
• Vancomycin-resistant Enterococcus faecium
(VRE): This organism can cause everything from urinary tract
to heart valve infections. A recent survey of U.S. hospitals
found a VRE rate of 10% in all patient groups. Rates are as
high as 70% in high-risk groups. Some strains can outmatch many
previously effective antibiotics.
• Pseudomonas aeruginosa: This pathogen
can cause severe infections that can be fatal, especially in
immunocompromised individuals. Rates of this pathogen have nearly
doubled from 1975 to 2003 (9.1% to 18%). It is particularly
virulent in children with cystic fibrosis. These patients often
die without lung transplants.
What Is Our Best Defense?
The answer is startling in its simplicity: wash your hands.
That’s right. In our era of high-tech super science and
complex relationships between causes, the simplest answer remains
paramount.
A now-famous study involving grade school students
showed that the group scheduled to wash their hands four times
per day had fewer sick days due to communicable and gastrointestinal
illnesses than the control group, which followed normal practices
for handwashing.18
How are we doing with handwashing? In a recent
comprehensive study involving 62 volunteers and 14 different
hygiene products, it was shown that soap combined with hot water
and scrubbing reduced pathogens to a manageable level.19 Opinions
vary on the use of antimicrobial soaps and waterless alcohol-based
agents.
Don’t we wish we knew who really washes
their hands thoroughly after using the toilet, before eating,
etc?
The truth is, far fewer people are today than
formerly. Why? Usually, the answer involves time restraints;
we are always in a rush. The second reason is that many parents
are no longer home reminding children to develop the habit.
Whatever the reason, poor handwashing is the
second leading cause of foodborne illness. I usually tell foodservice
managers to be “nags” because employees will probably
never wash their hands often or well enough without constant
reminders, warnings, etc. A very revealing question for managers
is: How often do you have to replace the soap in the handwashing
area? If the answer is infrequently, a problem exists.
And it is a problem. One study shows that 60%
of foodservice personnel did not wash their hands after using
the toilet.20 The same is true in the home environment. Estimates
are that 60% to 80% of people do not wash their hands after
using the restroom.
How are these statistics gathered? Several ways,
but a common one is to station an invisible observer (one confined
to a stall) who counts flushes and faucets being used. This
can easily be observed in any public restroom.
What is even more interesting is to watch the
procedures used for handwashing. Is cold water okay? Do we need
soap? Is three seconds long enough? A tour of the bathroom is
most educational and may offer a few surprises.
After finishing with the toilet, a person goes
to the sink and turns on the hot water. (Note the operative
word here is hot. Soaps are designed to work better in hot water.)
After this, the person touches the soap dispenser. Medical technology
students usually learn that the soap dispenser has a high contamination
count due to the pathogens present on the hands touching it.
After a cursory scrubbing, hands are rinsed and the faucet turned
off. Remember, this is the same faucet originally touched with
the contaminated hand.
Next, the person operates the towel dispenser,
but this often requires the touching of a lever or handle—more
contamination. No-touch dispensers are becoming common. Hot
air dryers? Bad idea. Hot air dryers increase the bacterial
count on the hands and in the local environment. In addition,
people rarely use hot air dryers long enough to ensure more
than 55% to 65% dryness and often complete drying by wiping
hands on clothes.21
After drying, the person reaches for the door
handle. Now remember, 60% to 80% of the other people leaving
through this door had failed to wash their hands. Is the picture
clear? This person’s hands may be more contaminated after
washing than before.
How Can We Improve on
This Process?
First, remember to not touch any surfaces. How? By obtaining
a paper towel first. Use this towel to touch the faucet, get
soap (yes, it can be done), and obtain more toweling. Most importantly,
use the towel to open the door. It is easy to reinforce this
by recalling the types of diseases spread by poor handwashing.
Even with these precautions, it is essential that persons handling
food be required to wash their hands a second time prior to
food preparation. This should be done in the handwashing sink
in the food preparation area.
Clearly, foodborne illness is not going away.
While familiar pathogens remain with us, new organisms continue
to appear. Food providers will always be an important line of
defense in protecting the public. Our fundamental practices
of temperature control, handwashing, and avoidance of cross-contamination
must continue to be reinforced, while new measures must be developed.
Education of workers will remain pivotal.
— Joyce Wilkins, MS, RD, has a bachelor’s
degree in human nutrition and foods from Cornell University.
She completed her dietetic internship at the University of Indiana
Medical Center and earned a master’s degree in dietetics
from Florida International University. She has worked in all
phases of dietetics and is currently an independent consultant
in southern California. She has lectured extensively on the
subject of food safety throughout the country for the past 20
years. Her company, Safe-at-the-Plate, is utilized by multiple
corporations for training and food safety support.
References
1. Marler Clark Attorneys at Law, LLP, PS. Taco
Bell E. coli Outbreak. Available here.
2. The Centers for Disease Control and Prevention.
Escherichia coli O157:H7. Frequently Asked Questions: What is
Escherichia coli O157:H7? Available here.
3. Iowa State University News Service. “ISU
food safety specialist provides spinach E. coli advice.”
September 15, 2006. Available here.
4. Fankhauser RL, Monroe SS, Joel NS, et al.
Epidemiologic and molecular trends of “Norwalk-like viruses”
associated with outbreaks of gastroenteritis in the United States.
J Infect Dis. 2002;186(1):1-7.
5. Benson V, Merano MA. Current estimates from
the National Health Interview Survey, 1995. Vital Health Stat
10. 1998; (199):1-428.
6. About Norwalk Virus. “What Is Norwalk
virus (Norovirus)?” Available here.
7. WAFF.com “Norovirus sharing spotlight
with flu this season.” April 16, 2007. Available here.
8. Parashar U, Quiroz ES, Mounts AW, et al.
“Norwalk-like viruses.” Public health consequences
and outbreak management. MMWR Recomm Rep. 2001;50(RR-9):1-17.
9. PandemicFlu.gov. Available here.
10. CBC News. “Avian flu: The next pandemic?”
March 1, 2007. Available here.
11. Institute of Food Science & Technology
Trust Food. Information Statement: Avian Influenza and Food.
2007. Available here.
12. AMR Research. “H5N1 Potential Impact."
13. International Association for Food Protection.
Perspectives on Avian Influenza Risk Management for Food Safety
Professionals. Available here.
14. “Ramona boy dies of rare infection.”
North County Times. February 5, 2007. Available here.
15. Nordenberg T. “Miracle Drugs vs. Superbugs
— Preserving the Usefulness of Antiobiotics.” FDA
Consumer. November-December 1998. Available here.
16. U.S. Food and Drug Administration Center
for Veterinary Medicine. Human-use Antiobiotics in Livestock
Production. April 28, 2000. Available here.
17. CBS News. “Super-resistant Superbugs.”
May 2, 2004. Available here.
18. Master D, Hess Longe DH, Dickson H. Scheduled
hand washing in an elementary school population. Fam Med. 1997;29(5):336-339.
19. LiveScience.com. “The Dirty Truth
About Washing Your Hands.” March 11, 2005. Available here.
20. Emery HC. Changing poor hand washing habits
— A continuing challenge for sanitarians. Dairy Food Environ
Sanitation. 1990;10(1):8-9.
21. Knights B, Evans C, Barrass S, et al. Hand
drying — A survey of efficiency and hygiene. London; The
Applied Ecology Research Group, University of Westminster. 1993.
Examination
1. Escherichia coli (E. coli) O157:H7 is particularly
dangerous to:
a. older adults.
b. young children.
c. immunocompromised individuals.
d. all of the above
2. Fresh produce is often problematic in the
control of foodborne illness because:
a. pathogens on this type of food are more virulent.
b. handlers are difficult to train.
c. chemical control is discouraged due to the delicate nature
of the food.
d. these products are often used in exotic recipes.
3. An example of a pathogen that may be spread
through airborne channels is:
a. Salmonella enteritidis.
b. Norovirus.
c. hepatitis A.
d. E. coli.
4. E. coli O157:H7 is a member of the EHEC group.
EHEC stands for:
a. enterohemolytic E. coli.
b. enteric-hepatic E. coli.
c. enterohemorrhagic E. coli.
d. endenogenousheme E. coli.
5. E. coli is an example of a:
a. virus.
b. bacteria.
c. spore.
d. prion.
6. The avian flu would likely spread very rapidly
if:
a. it could reproduce more rapidly.
b. the human receptors were located closer to the nose or throat.
c. birds are frozen prior to processing.
d. governments become more vigilant in monitoring outbreaks.
7. The Norovirus primarily affects the heart.
a. True
b. False
8. Employees with the Norovirus should be symptom-free
for _____ hours before returning to work.
a. 24
b. 36
c. 48
d. 72
9. The Norovirus attaches to the intestinal
wall with:
a. the protein ball.
b. the appendages.
c. The Norovirus does not attach to the intestinal wall.
d. the lipid layer.
10. Avian flu:
a. may be spread by eating the cooked muscle of infected poultry.
b. is not destroyed by cooking.
c. is not inactivated by disinfectants currently in use for
Salmonella.
d. is not destroyed by freezing.
