Transcript food posioning prese..

FOOD POISONING

Foodborne Diseases
 Apply to illnesses acquired by consumption of
contaminated food.
 Sometimes incorrectly referred to as food
poisoning.
 Includes :
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Foodborne intoxications
Foodborne infections.

Foodborne intoxication
By toxins, whether biological or chemical
e.g.
 Staphylococcus
 Fish poisons
 Heavy metals.

Foodborne infection
e.g. Salmonella
Vulnerable Groups
Food poisoning is more likely to affect people with
lowered resistance to disease than healthy people who
might show mild symptoms or none at all.
The following are particularly vulnerable to food
poisoning: • Elderly or sick people
• Babies
• Young children
•Pregnant women
Symptoms of Microbiological
Food Poisoning
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Vomiting
Abdominal pain
Diarrhea
Fever
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Others
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e.g. neurological;
Botulism
Causes of Foodborne Diseases
A- Infective
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Bacterial
Viral
Protozoa
B. Non infective (intoxication)
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Non Biological
a. Chemical Poisons
b. Heavy metals
c. Other organic Cpds
Food Poisoning (contd.)
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Physical contamination:objects falling in to food –
metal, glass, packaging
materials etc.
Chemical contamination:Bleach, cleaning chemicals
getting in to food
Natural contamination:
Poisonous plants and
berries, undercooked red
kidney beans
Causes of Foodborne Diseases (Continued)
Biological From:
a- Mushrooms
b- Harmful algal species
c- Fish e.g.
 Ciguatera Fish poisoning
 Scombroid Fish poisoning associated with
raised Histamine levels.
 Paralytic shell Fish poisoning [In Japan].
Causes Food Borne Disease
Bacteria
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Salmonella species
Campylobacter jejuni
Staphylococcus aureus
Clostridium perfringens
Clostridium botulinum
Bacillus and other sporing bacilli
Shigella species.
E.coli
Yersinia enterocolitica
Vibrio parahaemolyticus,
Aeromonas hydrophilia,
Streptococcus species Group C, E and G .
The other e.g. Listeria monocytogens
Causes Of Foodborne
Viruses
Unlike bacteria viruses do not multiply in Foods.
Acquired by:
a- Primary contamination
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From shell Fish
From Oysters
From Mussels
From Vegetables e.g Hepatitis A
From Vegetables irrigated by untreated water.
b- Secondary contamination.
 From Food handlers
e.g. Hepatitis A
Foodborne Viruses (Continued)
Viruses:
a- Hepatitis A
b- Hepatitis E
c- Small rounded structured viruses(SRSV)
e.g.
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Norovirus
Caliciviruses
Astroviruses
Rotaviruses
Causes of Foodborne Disease
Protozoae
1- Giardiasis.
2- Amoebiasis
3- Cryptosporiosis
4- Isospora
5- Balantidum
6- Blastocytosis hominis
7- Microsporidia
8- Toxoplasmosis (?)
Some Diseases Which Are Transmitted By Food
But Not Considered As Food Poisoning:
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Bovine tuberculosis (milk)
Brucellosis (milk)
Toxoplasmosis (meat)
Listerosis (milk products)
Mad cow diseases etc.
Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused
By Common Foodborne Pathogens*
Pathogen
Typical
Incubation
Period
Duration
Typical Clinical
Presentation
Assorted Foods
Salmonella
species
1-3 Days
4-7 Days
Gastroenteritis
Undercooked
eggs or
poultry,
produce
Campylobacter
jejuni
2-5 Days
2-10
Days
Gastroenteritis
Undercooked
poultry,
unpasteurized
Bacterial
dairy products
E. coli,
Enterotoxigenic
1-3 Days
3-7 Days
Gastroenteritis
Many foods
Shigella species
1-2 Days
4-7 Days
Gastroenteritis
Produce, egg
salad
Listeria
monocytogenes
2-6 weeks
Variable
Gastroenteritis,
meningitis
abortion
Deli meat,
hotdogs,
unpasteurized
dairy products
Bacillus cereus
1-6 hour
<24 hour
Vomiting,
Gastroenteritis
Fried rice, meats
Clostridium
botulinum
12-72 hour
Days-months
Blurred vision,
paralysis
Home-canned
foods, fermented
fish
Staphylococcus
aureus
1-6 hour
1-2 Days
Gastroenteritis,
particularly
nausea
Meats, potato &
pork,
unpasteurized
dairy products.
Yersinia
enterocolitica
1-2 Days
1-3 weeks
Gastroenteritis,
Undercooked
appendicitis-like pork,
syndrome
unpasteurized
dairy products.
Viral
Typical
incubation
period
Duration
Typical
clinical
presentation
Norovirus
1-2 Days
12-60 Hr
Gastroenteritis Under
cooked
shellfish
Hepatitis A
virus
15-50 Days Weeksmonths
Hepatitis
Assorted
foods
Produce,
undercooked
shellfish
Parasitic
Typical
incubation
Duration
Typical clinical
presentation
Assorted
foods
Cryptos
poridium
parvum
2-10 Days
Weeks
Gastroenteritis
Produce, water
Cyclospora
cayetanesis
1-11 Days
Weeks
Gastroenteritis
Produce, water
Toxoplasma
gondii
5-23 Days
Months
Influenza-like
illness,
Food
contaminated by
cat feces,
undercooked
lymphadenopathy
meat
Giardia
lamblia
1-4 Wk
Weeks
Gastroenteritis
Water
Taenia solium
Variable
Variable
Asymptomatic,
cysticercosis
Raw pork
Types of bacteria
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Spoilage: Not particularly
harmful bacteria which cause
food to go off
Beneficial: “Good Bacteria”
which are used to make yoghurt
and cheese
Pathogenic: Illness causing
bacteria
In order to grow and multiply germs need:
Time
Moisture
Food
Warmth
Flies
Waiting
Remember it like this
Too
Many
In ideal conditions where there is
Moisture, Food and Warmth (37degrees
centigrade is ideal), bacteria can double
every 10 to 20 minutes. They do this by
dividing in to two. This is called
Binary Fission
These cells are beginning to divide into two
After 10 minutes
After 20 minutes
After 30 minutes
After 40 minutes
cooking chicken to a core temperature
of 75°C should kill most of the bacteria
Time : 9.30
Bacteria : 0
Time : 9.40
Bacteria : 12,000
Time : 9.50
Bacteria : 24,000
Time : 10.00 Bacteria : 48,000
Time : 10.10
Bacteria : 96,000
Time : 10.20 Bacteria : 192,000
Time : 10.30 Bacteria : 384,000
Time : 10.40 Bacteria : 768,000
Time : 10.50 Bacteria : 1.5 million
From 0 to 1,536,000 in
only 80 minutes !!!!!!
Knife
contaminated
by blood
Bacterial Growth Curve
Numbers
Of
Bacteria
rapid
multiplication
no multiplication
Lag Phase
Stationary Phase
Numbers of
bacteria remain
constant as the
number
produced is
equal to the
number dying
Time (hours)
Numbers of
bacteria
decrease
Spore
A resting resistant phase of some bacteria
(including Clostridium Perfingens and
Botulinum and Bacillus Cereus). The
bacterium produces a protective coat which
helps it to survive high temperatures (up to
120°C) and lack of water. When favourable
conditions return, the spores split open and
release the bacteria which are then able to
grow and multiply
Bacterial cell
Spore forming inside cell
Spore Formation
This is what happens …………..
Cell
Spore forms
in cell
Cell
disintegrates
Spore is
released
Spore starts
to germinate
Spore
continues to
germinate
Now see as, in suitable conditions, the cell
begins to divide (binary fission)………………………….
Staphylococcus
Aureus
Found in human
nose and throat
(also skin)
Salmonella
Found in animals,
raw poultry and
birds
Bacillus Cereus
Found in soil,
vegetation,
cereals and
spices
Clostridium
Perfingens
Found in animals
and birds
Clostridium
Botulinum
Found in the soil
and associated
with vegetables
and meats
Important Microbial Causes of Food
Poisoning
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Toxin related
A. Staphylococcus aureus
 Short incubation period < 6 hours
 An intoxication
 Not infection
Important Microbial Causes of
Food Poisoning (Continued)
Clinical Features:
 Abrupt, violent
 Nausea, vomiting, cramps
(abdominal pain)
 Prostration
 Diarrhea, sub normal temperature
 Source infected human & food handlers
 Food contaminated
enterotoxin
produced
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Toxin is heat stable
Diagnosis:
1- Epidemiologically
2- Isolation of organism from suspected food.
3- Toxin detection in faeces of patients
(rarely done)
B- Bacillus cereus (from rice meals)
 Bacillus caereus is an spore forming aerobic
bacillus produces two types of enterotoxins.
a- Heat stable causing:
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emetic type of food poisoning
incubation period < 6 hours
vomiting, nausea
b- Heat labile causing:
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diarrheal type
incubation period 6-24 hours
“BOTH TOXINS ARE PREFORMED IN FOOD”
Clostridium Perfringens
 Causative agent: type A strains of C. perfringens (C.
Welchii)
 Gram positive anaerobic rod spore forming characterized
by sudden:
 Onset of colic
 Diarrhea
 Nausea
Pathogenesis
Incubation period 10-16 hours
Spore-vegetate in food, when swollen they
sporulate in the intestine and
Produce toxin
Diagnosis:
Detection of spores in food >105 spores
Detection of spore in faeces >106 spores
Botulism:
 Causative agent Clostridium Botulinum
 Gram positive anaerobic spore forming
 It produces a powerful toxin
 The most lethal (killing toxin) 3 Kg can kill the
whole population of the world.
Food sources:
 Canned food e.g. fish under anaerobic conditions.
Pathogenesis (Continued)
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Incubation period 12-24 hours under anaerobic
condition the spores germinate in the foods to
produce the toxin.
 Classified into A – G strains they produce the responsible
toxins A, B, E and F
 Toxin is heat labile
 Toxin inhibits release of acetylcholine at neurone muscular
junction leading to flaccid paralysis.
Symptoms:
Neurological (no gastrointestinal)
As abnormal eye movements
Listeriosis
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Causative agent
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Listeria monocytogenes
Gram positive rod aerobic
Resembles dipththeroids
Can multiply at lower temperature 4°C
Sources
Wide spread in dust, soil, water,
sewage, vegetation, animals feeds,
poultry, meat fish, vegetable
Diseases
In pregnant women = febrile illness
Neonates – meningitis
Immunocompromised patients – febrile illness
Food Poisoning Outbreaks:
1.Illness in a period of time - few hours, few
weeks.
2.In individuals who consumed common food.
3.Many acute cases can happen
4.Proper evaluation of cases and implicated
food is essential
5.Single cases are difficult to recognized
unless they have a distinctive clinical
syndrome e.g. Botulism
LABORATORY DIAGNOSIS OF
FOOD POISONING OUTBREAKS
1- Type of Food
2- Incubation period
3-Isolation of the
causative agent from
a- Patient faeces,
Vomit
b- From incriminated
food and related articles.
4- Investigation of Food
Handlers in the same
way.
LABORATORY INVESTIGATIONS
OF FOOD HANDLERS
1-Most Important to explain the procedure
2-Don’t frightened the food handlers
3-Look for Salmonellae, Giardia, Amebae
4-Stop work until three specimens are negative
Salmonellosis
 Caused by No typhoid causing Salmonellas.
 Called Food poisoning gastro intestinal Salmonellas.
 Cause about 85% of cases of Food poisoning or Food
borne diseases (Shawrma)
 They are
 Gram –ve rods belonging to Enterobactericaee group
 There are more then 2500 species of Salmonellas enterica.
Salmonellasis (Continued)
Pathogenesis:
Incubation period 12-72 hours may be
more depends on the dose of Bacteria
Swollen.
CAMPYLOBACTER JEJUNI
A common cause of infectious diarrhea.
Affect children.
Sources:
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Chicken (Shwarma)
Milk
Person to person spread.
Diarrhea extends 1- 3 days.
Gram stain of faces spiral organisms
Culture on selective medium at 42°C.
10 Golden Rules For The Food
Preparation
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Choose foods processed for safety
Cook food thoroughly
Eat cooked foods immediately
Store cooked foods carefully
Reheat cooked foods thoroughly
10 Golden Rules For The Food
Preparation (Continued)
6- Avoid contact between raw food and
cooked food.
7- Wash hands repeatedly.
8- Keep all kitchen surfaces meticulously
clean.
9- Protect food from insects, rodents and
other animals.
10-Use safe water.
Are you safe?
© British Nutrition Foundation 2003
What should you do
before you cook?
What clothing should your wear?
Why should you wash your hands?
When is it important to
wash your hands?
How would you know if the
ingredients are safe to use?
Why should you tie back long hair?
© British Nutrition Foundation 2003
Washing hands
Always wash hands before cooking and after:
• going to the toilet;
• handling raw food, e.g. meat;
• touching hair, the mouth, spots or cuts;
• coughing or sneezing into your hands;
• blowing your nose;
• going out of the kitchen, e.g. to put the
rubbish out.
© British Nutrition Foundation 2003
How would you know how
long these foods last?
All packaged food has a date mark.
A date mark:
• tells us by when a food is safe to eat;
• is in 2 formats:
• ‘use by’ or
• ‘best before’
© British Nutrition Foundation 2003
Is it safe to eat?
‘Use by’ dates are used for
perishable foods, e.g. cheese, milk
‘Best before’ dates are used for
less perishable foods, e.g. canned
baked beans, jar of jam and frozen
fish fingers.
© British Nutrition Foundation 2003
Where should these foods be
stored?
Different foods are stored in a variety of
ways to keep them safe to eat for longer.
Dry cupboard
© British Nutrition Foundation 2003
Refrigerator
Freezer
Raw and cooked foods
Raw meat and poultry
should be stored on the
bottom shelf of the fridge
to prevent crosscontamination.
© British Nutrition Foundation 2003
Fruit and vegetables
Always wash fruit and vegetables
before you eat or use them to cook.
This removes dirt and other
and other particles.
© British Nutrition Foundation 2003
Campylobacter
enteritis
Escherichia Coli
0157
Listeriosis
That’s the end of lesson 1!
Coming next lesson: Foodborne diseases
Typhoid and paratyphoid
fever
Dysentery
Enjoy your food!
© British Nutrition Foundation 2003
Shigellosis
Epidemiology
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Endemic in developing countries
Poor sanitation, crowding and flies
10 to 20 percent of enteric disease
50% of the bloody diarrhea or dysentery of young
children
Developed countries, single-source, food or waterborne outbreaks occur sporadically under cooked
food and contaminated water)
Substandard sanitary facilities.
Homosexual men
Shigella
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Family Enterobacteriaceae
G-ve,facultatively anaerobic, non-sporeforming rods.
Four serogroups (species)
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Serogroup A — S. dysenteriae
Serogroup B — S flexneri
Serogroup C — S. boydji
Serogroup D — S sonne
• Developing countries (most virulant);
 S. dysenteriae
 S flexneri
• Developed conteries
 S sonne
Differentiated from the closely related
Escherichia coli
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Pathogenicity
Physiology (failure to ferment lactose or
decarboxylate lysine) and serology
Clinical Manifestations - Shigella
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Person-to-person spread
Also food/water vectors
IP 24-48 hrs, disease 7 days & carried for 30 D
Vomiting and mild to moderate dehydration
Bloody diarrhea or dysentery
Nonbloody diarrhea
Fever, abdominal pain tenesmus with watery diarrhea
or scant stools with pus, blood, mucus
Complications
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Bacteremia uncommon
Convulsions 25% of Shigella infections involving children
under the age of 4 years
Ekiri syndrome, an extremely rare, fatal encephalopathy has
also been described in Japanese children with S sonnei or S
flexneri infections
Reactive arthritis (Reiter’s) 2% HLA-B27 S flexneri
Hemolytic-uremic syndrome S dysenteriae serotype 1
Protein loss
Pathogenesis — Shigella
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Fecal-oral
Infectious dose very low (< 200 bugs) 10-100
Invades mucosa with subsequent multiplication and
mucosal destruction
Invasiness property encoded on large 140 Mda IPA
plasmid InterCellular Spread (IcsA)
Shiga-toxin ( I& II)
• Exotoxin is an enterotoxin and cytotoxin
Diagnosis
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Shigellosis on the basis of fresh blood in the stool.
Neutrophils in fecal smears is also a strongly
suggestive sign.
Watery, mucoid diarrhea may be the only symptom
of many S sonnei infections
DDx
EIEC, Salmonella enteritidis, Yersinia enterocolitica,
Campylobacter species, and Entamoeba histolytica
Isolation Procedures - Shigella
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Enrichment media
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Plate media
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GN broth & Selenite broth
Low selectivity —MAC
Med selectivity — XLD
High selectivity — DCA, HEK
Caution — some Shigella strains are inhibited
by SS agar
Screening Procedures - Shigella
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Lactose or xylose NON-fermenting colonies
Screen suspect colonies biochemically
TSI — K/A I no gas / no H25
Some sonnei and fiexneri produce gas
Nonmotile, urease negative
Screen typical biochemically ID colonies with
grouping antisera
Antimicrobial Susceptibility Testing
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Shigella
Susceptibility testing should be done
Empiric treatment when susceptibility is not
known is TMP-SMX
Use Quinolone if resistance to TMP-SMX is
suspected
Control
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Prevention of fecal-oral transmission
Vaccines are not currently available, but some
promising candidates are being developed