Power point focusing on the harmful bacteria found in food industries and at home that could cause serious food poisoning. Aimed for students taking A2 Food Technology

1. FOOD TECHNOLOGY
Bacteria – Linked with Micro-organisms in Food
Production

2. SALMONELLA
 Is a genus of rod-shaped, Gram negative, spore forming
bacteria.
 Incubation period: 12-72 hours
 Duration f Illness: 4-7 days but can cause more serious illness
in older adults, infants and persons with chronic diseases.
 Symptoms: Diarrhoea, fever, abdominal cramps and vomiting
 Sources: Contaminated eggs, poultry, meat, unpasteurised
milk and juice, cheese, contaminated raw fruits and
vegetables.
To prevent contamination:
 Cook foods above the ‘danger zone’ (5-65°C) to kill micro-organisms
 Wash hands thoroughly
 Keep food properly refrigerated
 Separate cooked and uncooked food, and use separate
utensils for each.

3. LISTERIA MONOCYTOGENES
 Is a Gram-positive bacterium found in soil and water and some
animals, including poultry and cattle.
 Incubation period: 3-70 days
 Duration to illness: Days to weeks
 Symptoms: Fever, stiff neck, confusion, vomiting, sometimes
diarrhoea.
 Sources: Refrigerated pates or meat spreads, unpasteurised milk
and day products, raw sprouts, ready-to-eat deli meats and hot
dogs.
 Who’s at risk: Older adults, pregnant women, people with certain
diseases (cancer, liver disease, HIV/AIDS). Due to frequent
pathogenetically, causing meningitis in newborns, pregnant mothers
are advised not to eat soft cheeses (brie and feta for example).
To prevent contamination:
 Do not drink raw (unpasteurized) milk, and do not eat foods that
have unpasteurized milk in them.
 Wash hands, countertops, and utensils after handling and preparing
uncooked foods.
 Keep uncooked meats, poultry separate from vegetables, fruits,
cooked foods, and ready-to-eat foods.

4. CAMPYLOBACTER
 Is a genus of bacteria that are Gram-negative, spiral in shape
and microaerophilic.
 Sources: Raw and uncooked poultry, unpasteurised milk,
contaminated water.
 Symptoms: Diarrhoea, cramps, fever and vomiting, diarrhoea
may be bloody.
 Incubation period: 2-5 days
 Duration of illness: 2-10 days.
To prevent contamination:
 Always cook meat, especially poultry, to safe minimum
temperatures.
 Keep raw meat separate from other foods.
 Do not drink unpasteurised milk.

5. STAPHYLOCOCCUS AUREUS
 Type of bacteria commonly found on the skin and hair as well
as in the noses and throats of people and animals. Cause
food poisoning when a food handler contaminates food and
then the food is not properly refrigerated.
 Sources: Salads, such as ham, egg, tuna, chicken, potato,
and bakery products, such as cream-filled pastries and cream
pies
 Incubation period: 1-6 hours
 Duration of illness: 24-48 hours
 Symptoms: Nausea, vomiting, diarrhoea, loss of appetite,
sever abdominal cramps, mild fever
To prevent contamination:
 Wash hands and under fingernails vigorously with soap and
water before handling and preparing food.
 Keep kitchens and food-serving areas clean and sanitized.
 Store cooked food in a wide, shallow container and refrigerate
as soon as possible.

6. ESCHERICHIA COLI (E COLI)
 Is a Gram-negative bacillus which can grow both aerobically
and anaerobically.
 Sources: Gut of humans and warm-blooded animals, sewage,
water and raw meat.
 Symptoms: Abdominal cramps, vomiting, diarrhoea and in
some people haemorrhagic colitis (bleeding of the bowel).
Occasionally however, particularly in young children,
haemolytic uraemic syndrome (HUS) develops. This is a
condition which leads to kidney failure and death is 5-10% o
cases. HUS takes 1 – 2 weeks to develop.
 Incubation period: 1-6 days
 Duration of Illness: 5-10 days
To prevent contamination:
 Hygienic slaughtering practices reduces contamination of
carcasses by faeces
 Vulnerable populations (e.g. Children or Elderly) should avoid
consumption of raw/ undercooked meat or milk/ milk products.
 Cook all meat to at least 72°C.
 Wash fruit and vegetables.

7. CLOSTRIDIUM PERFRINGENS
 It is an anaerobic, spore forming bacillus. Food poisoning caused by
this bacterium is due to eating a food containing large numbers of
living bacteria which subsequently release a toxin in the intestine.
 Sources: Raw meat and poultry – bacteria from raw meat may
spread to cooked food through cross contamination. Food handlers,
insects and reheated food can contaminate.
 Symptoms: Nausea, Abdominal pains, Diarrhoea and Vomiting
(although this is rare)
 Incubation period: 8-22 days
 Duration of Illness: 12-48 hours
To prevent contamination:
 Since this bacteria form heat-resistant spores it cannot be assumed
that the bacteria are killed during cooking. In order to lower the risk
of clostridium perfringers, the following precautions should be taken:
 Joints of meat (+3Kg) should be cut into smaller pieces before
cooking.
 Raw and cooked meats stored separately.
 Reheating of meat should be avoided if possible. If necessary the
meat should be heated and served quickly.

8. CLOSTRIDIUM BOTULINUM
 A Gram-positive, anaerobic, spore-forming bacillus.
 Produces an exotoxin whilst growing in food and is one of the
most lethal poisons known.
 Illness caused by the organism Botulism.
 Sources: Soil, some fish and vegetables and some canned,
bottled and vacuum packed foods.
 Symptoms: Toxin affects central nervous system. Early
symptoms include double vision, difficulty with speech,
headache and dizziness.
 Incubation period: 18-36 hours
 Duration of Illness: 1-8 days
To prevent contamination:
 Botulinum toxin is destroyed by heat. Heating to 80°C for 15
minutes is sufficient to destroy the toxin.

9. BACILLUS CEREUS
 A Gram-positive, spore-forming, aerobic bacillus.
 It produces a heat-resistant exotoxin which is released into
food. The toxin can survive for 1.5 hours at 121°C.
 Sources: Soil, dust and water. Frequently present in cereal
foods – particularly rice and cornflour. Some rice dishes
(boiled and fried) and milk puddings.
 Symptoms: Vomiting, abdominal pains and some diarrhoea.
 Incubation period: 1-6 hours
 Duration of Illness: 6-24 hours
To prevent contamination:
 Rice dishes, milk puddings and cornflour sauces should be
cooled quickly (within 90 minutes).
 Re-heating food should be heated quickly and thoroughly and
served as soon as possible.