Small help for the exam

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.