Download Staphylococcus aureus

FOOD INTOXICATIONS
Britni Mahan and Beth Johnson
WHAT IS FOOD POISONING?
Food poisoning is an illness caused by eating
foods that have harmful organisms in them.
 Includes: bacteria, parasites, fungi, and viruses.
 Mostly found in raw meat, chicken, fish, and
eggs, but can spread to any type of food.
 Can also grow on food that is left out on counters
or outdoors or is stored too long before you eat it.
 Sometimes food poisoning is caused by people
not washing their hands before they touch food.

CAUSES
Food poisoning can affect one person or it can
occur as an outbreak in a group of people who all
ate the same contaminated food.
 Food poisoning tends to occur at picnics, school
cafeterias, and large social functions. In these
cases, food may be left out of the refrigerator too
long or food preparation techniques may not be
clean. Food poisoning often occurs from eating
undercooked meats, dairy products, or food
containing mayonnaise (like coleslaw or potato
salad) that have sat out of the refrigerator too
long.

SIGNS AND SYMPTOMS

Most commonly
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Diarrhea
Vomiting
Stomach cramps
Nausea
Headaches
Fever
TYPES OF FOOD POISONING
Infection

The microorganism
itself grows inside
your body and is the
source of your
symptoms
Intoxication

A chemical or natural
toxin (often produced
as a by-product of
bacteria present in the
food - known as an
exotoxin)
We will be focusing on food intoxications
TREATMENT FOR FOOD INTOXICATIONS
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In most cases, food intoxications go away on their own
in 2 to 3 days.
Rest and plenty of fluids to prevent dehydration.
Doctors recommend trying to eat normally as soon as
possible. But, follow a BRAT diet (Bananas, Rice,
Applesauce and Toast) until you can eat without
vomiting
Try to stay away from foods that are high in fat or
sugar
Antibiotics are usually not used to treat food
poisoning, they can actually worsen the symptoms.
Medicines that stop diarrhea (anti-diarrheals) can be
helpful, but they should not be given to infants or
young children.
COMPLICATIONS AND LONG TERM
EFFECTS
Most types of food poisonings only lead to severe
dehydration and do not lead to long term effects or
conditions. Here are some examples that do.
 Arthritis (Yersinia and Salmonella)
 Bleeding disorders (E. coli and others)
 Death (from mushrooms, certain fish poisonings, or
botulism)
 Kidney problems (Shigella, E. coli)
 Nervous system disorders (Botulism, Campylobacter)
 Pericarditis Salmonella)
 Respiratory distress, including the need for support
on a breathing machine (botulism)
MOST COMMON TYPES OF FOOD POISONING
The most common types of food poisoning are
caused by bacteria such as:
 Staphylococcus aureus
 Salmonella
 Clostridium botulinium
 Vibro parahaemolyticus
 Bacillus cereus
 Listeria monocytogens
 Campylobacter jejuni
 Versinia enterocolotica
 Enteropathogenic E. coli
FRIDAY’S SPECIAL
OOOPS… SHOULD HAVE
BROWN BAGGED IT
By Dr. Beth Johnson
Flamingham General Hospital
April 23, 2009
PATIENT BACKGROUND
ANATOMICAL AND EPIDEMIOLOGICAL
DIAGNOSIS
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Mary Kate De Sausalito
16 years old girl
History of malaise since noon followed by severe
abdominal cramps, headache and weakness
In transit to hospital patient experienced perfuse and
continuous vomiting.
PATIENT BACKGROUND
ANATOMICAL AND EPIDEMIOLOGICAL
DIAGNOSIS
Patient did not appear to be in acute distress, but
did vomit a few more times during interview.
 Patient also experienced profuse watery diarrhea
during initial exam.
 Patient claimed to have no family history. She
was adopted and may have an identical twin
sister, but there are no records.

CONTINUED EPIDEMIOLOGICAL DIAGNOSIS
Mary Kate is a high school cheerleader and
frequently stays after school for practices and
games. Being in heavily populated areas and in
close contact with others on a regular basis can
make one more susceptible to catch a contagious
infection. In addition, Mary Kate gets her
lunches from the school cafeteria, which also
increases her risk of a food borne illness.
EXAM IN THE ER
Patients vitals were taken and came back normal
Patient
Normal
Temp 37.1 C
Pulse 110 BPM
37.0 C
70-100 BPM
Systolic: 110 - 140mmHg
BP 110/9mmHg
Diastolic: 70 - 90 mmHg
Respirations 20/Min
15-20 /Min
THE LIKELY SUSPECTS
It was clear to me with Mary Kate’s vital signs
being normal coupled with her signs and
symptoms, that she had become the victim of food
poisoning (food-borne illness).
Food-bourne illness-(food poisoning) is any
illness resulting from the consumption of food.
There are two types
THE LIKELY SUSPECTS
Food borne infection and Food Intoxication
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Food Infection- Refers to the presence of bacteria
or other microbes which infect the body, after
consumption of food.
Food Intoxication- Refers to the ingestion of
toxins contained within the food, including
bacterially produced exotoxins which can happen
even when microbe which produced the toxin is
no longer present.
THE LIKELY SUSPECTS
Most Cases are caused by:
 A variety of pathenogenic bacteria
 Viruses
 Parasites
Common Symptoms include:
 Nausea/Vomiting
 Abdominal Pain
 Diarrhea
 Fever
 Headache
 Fatigue
 Gastroenteritis
POTENTIAL MICROBES
My initial differential diagnosis showed that
there were twenty seven microbes that could
have been the potential cause of Mary Kate's
illness.
But after careful research of the microbes, I
ruled out 24 of them and focused on the four that
were most like the signs and symptoms my
patient was exhibiting.
AND
THE
CONTESTANTS
WERE
DIFFERENTIAL DIAGNOSIS
Staphylococcus aureus-- Type of gram positive
food poisoning caused by infection with the
Staphylococcus aureus bacterium. Bacteria
multiply in foods and produce a toxin even at
refrigeration temps. The toxin may be present in
dangerous amounts in foods with no sign of
spoilage.
 Reason to consider- it is known for abrupt onset
of intense vomiting and diarrhea for up to 24
hours with an incubation period of 2-8 hours.
This microbe is a likely cause of the patients
illness in regards to her vomiting and diarrhea.

DIFFERENTIAL DIAGNOSIS
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Salmonella spp- (gastroenteritis) A gram neg food
poisoning that grow in gut.
Reason to consider- Clinical features include gradual
or abrupt onset of diarrhea and low grade fever,
nausea, headache and muscle aches.
DIFFERENTIAL DIAGNOSIS
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Trichina spiralis- a parasitic worm that lives in
the intestines and causes a serious illness known
as trichinosis. The eggs usually enter the body
via raw or undercooked pork, sausage, or bear
meat. The eggs hatch mature in the intestines
and migrate to other parts of the body through
the bloodstream and lymph system.
Reason to consider- Early symptoms include
vomiting, diarrhea, and abdominal cramps. In
time, a high fever and puffiness of face and
muscle pain develop.
DIFFERENTIAL DIAGNOSIS
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
Norwalk virus- (stomach flu) Intestinal illness
that often occurs in outbreaks, increasingly being
recognized as the leading causes of food bourne
disease in the U.S. Virus is passed in stool of
infected person, people get infected by swallowing
stool contaminated food or water. Also outbreaks
are often linked to raw oysters.
Reason to consider- Signs and symptoms of this
virus are nausea, vomiting, diarrhea, and
stomach cramps. Similar to that of the patient.
SPECIMENS TESTED
STOOL/VOMIT SPECIMENS WERE TESTED ON:
 BLOOD
 MAC
 SS
 CAMPY
 SELENITE
 HE
BLOOD SPECIMENS WERE TESTED ON:
 BLOOD
 CHOC
 MAC
 ANA
RESULTS
THE RESULTS OF THE AGAR
PLATES DEMONSTRATED NO
SIGNS OF INFECTION. THE
ONLY GROWTH ON PLATES
WAS OF NORMAL FLORA
THAT IS NORMALLY FOUND
WITHIN THE GUTS OF
HUMANS.
WBC COUNT
MARY KATE
NORMAL
SEGMENTED
NEUTROPHILS
61%
BANDED
NEUTROPHILS
1%
44-77%
0-5%
BASOPHILS
2%
0-2%
EOSINOPHILS
1%
0-7%
LYMPHOCYTES
31%
16-43%
MONOCYTES
4%
2-10%
RULING OUT
The results of the WBC Counts helped me to rule
out the possibility of a parasitic infection. If the
cause were Trichinosis, my patients white blood
cell count would have been elevated due to an
increase in antibodies created to fight off this
infection.
Mary Kates wbc count would also have been
elevated had my patient been infected with the
Norwalk Virus.
A TOSS UP
Now that the virus and parasites are ruled out, the
last of my possible candidates are:
 Salmonella spp
and
 Staphylococcus aureus
Helping me to determine that the cause of Mary
Kate's illness as Bacterial Gastroenteritis.
CONTINUED EPIDEMIOLOGICAL
DIAGNOSIS
Not long after my patients admission to the
hospital, 35 more students from Mary Kate’s
High School of whom all share the same lunch
period show up in the emergency room, all with
the same symptoms.
I immediately called the hospitals infection control
officer regarding a potential outbreak of food
poisoning at a local school, and ordered test on
the food that was served that day.
RESULTS OF TESTED FOOD
When the cultures of the food came back, the
results showed gram positive cocci that were
produced on TSA, BLOOD and PEA and there
was no growth on the MAC.
No growth on the MAC ruled out the possibility of
a the gram negative bacterial infection of
salmonella.
Growth of gram positive cocci reinforced the likely
hood of Staphylococcus aureus food poisoning.
THE CULPRITE
Staphylococcus aureus
 Facultative anaerobic gram positive cocci that
makes ATP by aerobic respiration, if oxygen is
present, but is also capable to switch to
fermentation.
 Microscopic -grape like clusters
 Macroscopic - golden yellow colonies
 20 % of population are long term carriers
SOME INFECTIONS CAUSED BY
STAPHYLOCOCCUS AUREUS
In addition to food poisoning, this bacteria can also
cause minor skin infections such as:
 Impetigo
 Pimples
 Boils
 Cellulitis
As well as more life threatening diseases such as
 Pneumonia
 Meningitis
 Toxic Shock Syndrome
WHAT IS STAPH AUREUS FOOD
POISONING?
Staphylococcal food poisoning is a
gastrointestinal illness caused be eating foods
contaminated with the toxins produced by
Staphylococcus aureus.
 The most common way of contamination is
through workers who carry the bacteria or
through contaminated milk and cheeses.
 Staphylococcus aureus produces an
enterotoxin (a type of exotoxin or protein toxin
that is released by microorganisms in the
intestines).

WHAT IS STAPH AUREUS
POISONING?
FOOD
Staphylococcus is salt tolerant and can grow in
salty foods like ham.
 As the germ multiplies in food, it produces toxins
that can cause illness.
 Staphylococcal toxins are resistant to heat and
cannot be destroyed by cooking.
 Foods at highest risk of contamination with
Staphylococcus aureus and subsequent toxin
production are those that are made by hand and
require no cooking such as puddings, some
pastries and sandwiches.

SIGNS AND SYMPTOMS
Staphylococcal toxins are fast acting, sometimes
causing illness in as little as 30 minutes.
 Symptoms usually develop within one to six
hours after eating contaminated food.
 Patients typically experience several of the
following: nausea, vomiting, stomach cramps,
and diarrhea.
 The illness is usually mild and most patients
recover after one to three days. In a small
minority of patients the illness may be more
severe.

HOW DO KNOW IF I HAVE STAPH
FOOD POISONING?
Toxin-producing Staphylococcus aureus can be
identified in stool or vomit, and toxin can be
detected in food items.
Diagnosis of staphylococcal food poisoning in an
individual is generally based only on the signs
and symptoms of the patient.
Testing for the toxin-producing bacteria or the
toxin is not usually done in individual patients,
but is usually reserved for outbreaks involving
several persons.
INITIAL EXAM
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Abdominal examination was notable for abdominal
tenderness
The remainder of her physical exam was
unremarkable. She had an “urgent” conversation
with a nurse, who escorted her to the ladies’ room;
the nurse immediately informed you that Ashley
had profuse, watery diarrhea.
As you concluded your examination of Ashley, the
admitting clerk warned you that tons of kids were
throwing up all over the waiting room
Claimed to have no family history. She was adopted
and may have an identical twin sister, but there are
no records
TREATMENT
The best treatments for these patients are rest,
plenty of fluids, and medicines to calm their
stomachs.
 Highly susceptible patients, such as the young
and the elderly, are more likely to have severe
illness requiring intravenous therapy and care in
a hospital.
 Antibiotics are not useful in treating this illness.
The toxin is not affected by antibiotics.
 Patients with this illness are not contagious.
Toxins are not transmitted from one person to
another.
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PREVENTION
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It is important to prevent the contamination of food
with Staphylococcus before the toxin can be produced.
Wash hands and under fingernails vigorously with
soap and water before handling and preparing food.
Do not prepare food if you have a nose or eye
infection.
Do not prepare or serve food for others if you have
wounds or skin infections on your hands or wrists.
Keep kitchens and food-serving areas clean and
sanitized. If food is to be stored longer than two
hours, keep hot foods hot (over 140°F) and cold foods
cold (40°F or under).
Store cooked food in a wide, shallow container and
refrigerate as soon as possible.
PROGNOSIS
After a little TLC, Mary Kate and her classmates
were all back to normal the following day.
THE BEST CAFETERIA DAY OF THE MONTH
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Ashley de Sanfrancisco
16 years old
Chow mein lover
By 5 PM:
severe abdominal
cramps
 headache
 felt weak
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Sent to hospital and
vomited on the way, but
arrived in apparent
“good health”
BEWARE THE IDES OF MARCH
HOSPITAL ADMISSION

Vomited twice while being interviewed, but did not
appear in acute distress

Normal Values
Patient's
Body Temperature 37oC
(T)
37.1oC
Heart Rate (Pulse) 60-100/min (higher for
infants and children)
Respiratory Rate 9-18/min (higher for
(Respiration)
infants and children)
110 beats/min
Blood Pressure
(BP)
110/90 mm Hg
90-150/50-90 (lower for
infants and children)
20 breaths/min
SPECIMEN REQUEST’S
-Blood
NO SMEAR – This Specimen is NOT Routinely Gram Stained
BLOOD
CHOC
MAC
ANA
- Stool
&Vomitis
NO SMEAR – This Specimen is NOT Routinely Gram Stained
Upon Special Request - EXAMINATION FOR LYMPHOCYTES
BLOOD
MAC
HE
SS
CAMPY - Incubate at 42oC
SELENITE - Place Remaining Specimen on Swab in Selenite Broth
CBC RESULTS
Complete Blood Count (CBC)
White Blood Cell (WBCs)
- Neutrophils
- Segmented Neutrophils
- Banded Neutrophils
Normal Values
4,000-10,000/mm3
47 - 77%
Patient's
9500/mm3
62%
60 - 70%
61%
0 - 5%
1%
- Basophils
0 - 2%
- Eosinophils
0 - 7%
1%
Monocytes
2 - 10%
4%
Lymphocytes
16 - 43%
31%
2%
LIKELY SUSPECTS
The Stool and Vomitis specimens were still
pending..
 35 students were admitted with similar
symptoms, they all shared same lunch period
 S. aureus was my most likely suspect at this
point, but considering B.cereus because of the
rice.
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The 2 pathogens have similar same signs and
symptoms and are often difficult to initially
distinguish from one another
A sample of the rice that the students ate was
ordered at this point to definitively identify the
pathogen causing my patient’s illness.
CAUSE: BACILLUS CEREUS
The cultures of the STOOL and VOMITIS grew
out “normal flora.”
 The cultures of the FOOD from the school
cafeteria produced Gram-positive bacilli that
grew on TSA, BLOOD, and PEA, but “no growth”
on MAC.

BACILLUS CEREUS
Gram-positive, facultative
aerobic spore former which
produces two types of
toxins. Most B. cereus are
motile
 B. cereus is beta hemolytic
(the bacteria's hemolytic
enzymes completely break
down blood cells)
 The β-hemolysis pattern
results in the media
displaying clear halos
around bacterial colonies.

B. Cereus on a blood agar plate
BACILLUS CEREUS FOODBORNE ILLNESSES
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Occur due to survival of the bacterial endospores
when food is improperly cooked. This problem is
compounded when food is then improperly
refrigerated, allowing the endospores to germinate.
Bacterial growth results in production of enterotoxin
(a protein toxin released by a microorganism in the
intestine), and ingestion leads to two types of illness:
The emetic illness is caused by the ingestion of a heatstable toxin produced by the microorganisms in the food.
 The diarrheal illness is caused by the ingestion of moderate
to high number of B. cereus and their subsequent
production of toxin in the stomach.

B. CEREUS FOOD POISONING
Diarrheal

Diarrheal type food
poisoning mimic signs
and symptoms of
Clostridium perfringens
food poisoning.

6-15 hours after
consumption -watery
diarrhea, abdominal
cramps, and pain occurs
*Nausea may accompany
diarrhea, but vomiting
(emesis) rarely occurs.
Symptoms persist for 24
hours in most instances
Emetic
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Characterized by nausea
and vomiting within 0.5 to
6 hours after consumption
of contaminated foods.
Occasionally, abdominal
cramps and/or diarrhea
may also occur.
Duration of symptoms is
generally less than 24 h.
The symptoms of this type
of food poisoning parallel
those caused by
Staphylococcus aureus
foodborne intoxication
SOURCES
A wide variety of foods including meats, milk,
vegetables, and fish have been associated with
the diarrheal type food poisoning.
 The vomiting-type outbreaks have generally been
associated with rice products; however, other
starchy foods such as potato, pasta and cheese
products have also been implicated.

DIAGNOSIS
The rapid onset time to symptoms in the emetic
form of disease, coupled with some food evidence,
is often sufficient to diagnose this type of food
poisoning.
 Isolation of B. cereus serotype in food and vomitis
or stools of patients is also done
 Large numbers of enterotoxigenic Bacillus cereus
were isolated from the rice that was part of the
lunch served to the students.
 Reverse passive agglutination was used to
demonstrate the presence of entertoxin type in
the patient’s vomitis and in the leftover rice.

OTHER COMPLICATIONS ASSOCIATED WITH
B.CEREUS
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Although no specific complications have been
associated with the diarrheal and vomiting toxins
produced by B. cereus, other clinical manifestations of
B. cereus invasion or contamination have been
observed.
Bovine mastitis
severe systemic and pyogenic infections
gangrene
septic meningitis
cellulitis
panophthalmitis
lung abscesses
infant death
endocarditis
TREATMENT
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Due to the apparent nature of this outbreak of food
poisoning, I decided not to admit my patient for
further diagnostic testing.
She was sent home with orders that included
supportive therapy [drink plenty of fluids, etc.] but no
antibiotic therapy was needed. Most cases of Bacillus
cereus food poisoning resolve themselves without
medical treatment
Antibiotics are normally not given, as the bacteria
have been found to be resistant to penicillin and
antibiotics are rarely needed for food poisoning. In
some cases, antibiotics worsen the condition.
This illness cannot be spread by person to person
contact. The only way to contract the illness is by
consuming contaminated food.
PREVENTION
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To prevent food poisoning, take the following steps when
preparing food:
Carefully wash your hands and clean dishes and utensils.
Use a thermometer when cooking. Cook beef to at least
160°F, poultry to at least 180°F, and fish to at least 140°F.
DO NOT place cooked meat or fish back onto the same
plate or container that held the raw meat, unless the
container has been completely washed.
Promptly refrigerate any food you will not be eating. Keep
the refrigerator set to around 40°F and your freezer at or
below 0°F. DO NOT eat meat, poultry, or fish that has been
refrigerated uncooked for longer than 1 to 2 days.
DO NOT use outdated foods, packaged food with a broken
seal, or cans that are bulging or have a dent.
DO NOT use foods that have an unusual odor or a spoiled
taste.
PREVENTION
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If you take care of young children, wash your hands often and
dispose of diapers carefully so that bacteria can't spread to
other surfaces or people.
If you make canned food at home, be sure to follow proper
canning techniques to prevent botulism.
DO NOT feed honey to children under 1 year of age.
DO NOT eat wild mushrooms.
When traveling where contamination is more likely, eat only
hot, freshly cooked food. Drink water only if it's been boiled.
DO NOT eat raw vegetables or unpeeled fruit.
DO NOT eat shellfish that has been exposed to red tides.
If you are pregnant or have a weakened immune system, DO
NOT eat soft cheeses, especially imported from countries
outside the U.S.
If other people may have eaten the food that made you sick, let
them know. If you think the food was contaminated when you
bought it from a store or restaurant, tell the store and your
local health department