Microbiology is the scientific field that is occupied with the study of microscopic organisms, commonly known as micro-organisms.
What are Micro-organisms?
All living creature consist of cells. Cells are very small basic units of life. They are the smallest structures capable of basic life process, such as taking in nutrients and expelling waste.
Micro-organisms are organisms that usually consist of one single cell. Because of this, they are often referred to as single celled organisms.
What kinds of Micro-organisms are there?
There are two kinds of micro-organisms.
Protista (eukaryotic): They contain nucleuses, surrounded by membrane.
Monera (prokaryotic): They contain no nucleus and other internal parts, surrounded by a membrane.
Monera are bacteria & cyanobacteria and Protista are single celled eukaryotic micro-organisms, example are amoebdiatoms, algae and protozoa.
What are Bacteria?
They are single cell organisms usually having a definite outer envelope or capsule for protection. They multiply by dividing into two, which can occur very quickly, (eg. every 20 minutes). They can actively move and some link themselves together in chains or in bunches.
To resist harm, some bacteria can form spores (tough reproductive cells that are able to survive under adverse conditions), that can resist damage by heat (as in cooking), by cold (as in freezing) and by chemicals such as disinfectants. A spore can survive in dust, on vegetation and in soil for weeks, months or even years until it finds itself in a suitable environment for growth.
Bacteria are the main cause of food-borne illness or food poisoning and are an important cause of food spoilage.
They thrive where food and water are present and the temperature is suitable, as in the nose, throat, skin, bowel and lower urinary tract of man and animals.
What are Viruses?
Viruses are organisms much smaller than bacteria. In their pre-infective stage they are just like a chemical with none of the requirements for life, but once in a living cell they take over and begin to multiply. They can grow only in living tissue, but can be carried in food from one person to another.
What are Yeasts?
Yeasts are single cell organisms much larger than bacteria and can be found in the soil, on plants and on the skin and body of man. They multiply by forming offspring as buds which grow and then detach themselves.
Some can produce disease, some cause skin infections in man and others cause diseases in plants. Some yeasts spoil food, but beneficial uses are in the making of beer, wine and bread.
What are Moulds?
Moulds grow as single cell filaments that can branch together making a strongly knit tructure like a mat, that can often be seen with the naked eye. Usually they look fluffy, being a familiar sight on foods like jam, cheese and bread. They multiply by producing clusters of dry spores which are blown by the air like seeds.
Many moulds spoil food and a few can cause disease in plants and man, but beneficial uses are in the ripening of cheeses and production of antibiotics.
What is Salmonella?
The Salmonella Bacterial organism is very common in both animal and vegetable matter in their raw state. It is impossible to eradicate completely due to its omnipresence but it is vital to keep outbreak under control at source. In the food chain the bacterial organism could reach the gastrointestinal tract causing severe dysentery and fever. Some strains are fatal to young babies, the elderly, those who are frail and those with a compromised immune system.
What is Enterobacteriaceae?
Enterobacteriaceae is a single family of bacteria, which consists of Coliforms, Enterobacter, Serratia, and Proteus that occur mainly in soils and water and in plant pathogens of the genus erwinia. Some of these species live in the intestines of man and other animals and can sometimes cause intestinal disturbances. None are particularly heat resistant and thus all are easily eliminated from food and animal feed by heat treatment, such as, pasteurisation of milk.
What are Pathogens?
A Pathogen is a parasite that causes diseases in man, animals and plants. Pathogens vary widely in there ability to harm the host species. Pathogens are determined by two factors; first they’re ability to multiply in host body and their ability to produce toxins that damage the tissue of the host. Examples of some of the common diseases caused by pathogens are Influenza, Gastroenteritis, and Aids.
What are foodborne illnesses?
Foodborne illnesses are caused by eating food or drinking beverages contaminated with bacteria, parasites, or viruses. Harmful chemicals can also cause foodborne illnesses if they have contaminated food during harvesting or processing. Foodborne illnesses can cause symptoms that range from an upset stomach to more serious symptoms, including diarrhea, fever, vomiting, abdominal cramps, and dehydration. Most foodborne infections are undiagnosed and unreported, though the Centers for Disease Control and Prevention estimates that every year about 76 million people in the United States become ill from pathogens, or disease-causing substances, in food. Of these people, about 5,000 die.
Food Poisoning and Spread of Disease
"Food poisoning" is a general name given to illnesses contracted by consuming contaminated food or water.The micro-organisms responsible for illness are bacteria, viruses and fungi, commonly called "germs: or "bugs". But illness can also be caused by chemical contaminants (such as heavy metals), toxins produced by the growth of some micro-organisms (eg. Staphylococci bacteria) and by a variety of organic substances that may be present naturally in foods (such as certain mushrooms and some seafood).
Generally food poisoning results from contamination of food and the subsequent growth of food poisoning micro-organisms.
Food poisoning outbreaks are often recognised by the sudden onset of illness within a short period of time among many individuals who have eaten or drunk one or more foods in common.
Single cases are difficult to identify unless, as in Botulism for example, there are distinct symptoms.
Food poisoning may be one of the most common causes of acute illness; yet cases and outbreaks are generally under-recognised and under-reported.
Common Food Poisoning Illness
Contaminated meat and meat products, especially poultry Custard, cream, milk and egg products, and salads
Fever, headache, aching limbs, abdominal pain, nausea, diarrhoea, and sometimes vomiting
Onset of Illness
6 to 72 hours (usually 12 to 36 hours)
Salmonella bacteria are often present in the waste of
man and animals, (especially rodents and poultry).
This illness is infectious and can be spread to other
Contaminated moist protein foods. Meat, eggs and fish products
Abdominal pain, severe vomiting, diarrhoea, abdominal cramps, and
Onset of Illness
1 to 6 hours (usually 2 to 4 hours)
Staphylococcal bacteria may come from infected sores, nasal secretions and
skin (perspiration and hair). The toxin that causes illness can survive
Contaminated processed meats and meat products, raw milk, seafood, poultry
and vegetables etc
Acute/mild fever, influenza-like symptoms
Fever, intense headache, nausea, meningeal irritation
and vomiting. Infection of the foetus, septicemia,
meningitis, and still-birth
Onset of Illness
3 days to 3 weeks
Listeria bacteria are commonly found in soil, water, vegetation, domestic
animals, and man.
The illness, though infectious, is relatively rare.
At Risk Hosts Pregnant women, the elderly, and those
with lowered immune systems.
The ten main reasons for Food Poisoning
Inadequate cooling/refrigeration, Food left at room temperature.
Too long between preparation and consumption.
Cross-contamination from raw to high risk/ready to eat foods.
Infected food handlers.
Inadequate hot holding temperatures.
Inadequate hand washing.
Contaminated raw foods and ingredients.
Improper cleaning of equipment and utensils.
Which micro-organisms in water cause diseases?
Very thin blood and mucus containing diarrhea
Flue, diarrhea, head & stomachaches, fever, cramps
Flu, swelling of lymph glands with pregnant women
subtle abortion and brain infection
How do we eliminate harmful micro-organisms from water?
To eliminate harmful microorganisms from water we tend to use disinfectants. Disinfectants are chlorine, UV, ozone (O3) and chlorine dioxide (ClO2).
What are the possible contaminations of air treatment systems with legionella bacteria?
Ait treatment systems in buildings, also known as airco or airconditioning system, are related to the risks of a legionnaires disease out break.
What is the origin of the legionella bacteria are what are the risk?
The legionella preumophila bacteria is naturally occurring in surface water (even in drinking water). However to grow and multiply it needs nutrients, a place to grow like present in biofilm, and a water temperature between 20 to 55 degrees. If a group of legionella bacteria is released from the biofilm and the water in which it houses is sprayed and inhaled by people with impaired immune defence it can cause the feared legionnaires disease.
Why do we have microbes in our gut?
Without microbes we could not digest our food properly. Thanks to the bacteria inside the colon, which ferment about 100g of food each day, this part of our digestive tract is probably the most active organ in the body.
How many microbes live in our body?
There are more microbial cells in our body than there are human cells! in fact 95% of all the cells in the body are bacteria, mainly living in the digestive tract. There are more bacteria in the colon than the total number of people who have ever lived. everyone has about 1 kg in weight of bacteria in their gut. Each gram of faeces contains 100,000,000,000 microbes. Human adults excrete their own weight in faecal bacteria every year.