Unit L6165045 - Cause and spread of infection
Understand the causes of infection
1.1 Identify the differences between bacteria, viruses, fungi and parasites
Bacteria, viruses, pathogenic fungi and parasites are all examples of micro-organisms that can
cause infection.
1. Bacteria
Bacteria are the most common cause of infection in the health care setting.
Most bacteria consist of only one cell and reproduce by dividing in half. They often group
together to form colonies. Scientists classify and name them in many different ways, for
example, by their shapes or by the way they stain.
By their shape bacteria can be:
round – they are called cocci
spiral-shaped – they are called spirilla, or
rod-shaped – they are called bacilli
It is very interesting, for example, if I could hear ’Staphylococcus’, I would know that the
person has an infection caused by a round bacterium, because of the word: ’coccus’.
Bacteria have two types:
aerobic bacteria need oxygen to live, while
anaerobic bacteria die if oxygen is present
Bacteria feed themselves by making their food with the use of sunlight and water. The human body
consists of lots of ’friendly’ bacteria, which protect us from dangerous ones by occupying places in the
body. We would not be able to live without them.
Most bacteria, that can cause illness need a warm, moist and dark environment, as well as a
source of nutrition in order to grow (the inside of the human body can be a perfect place for
them).
2. Viruses
Viruses are the smallest of all microbes. We can see them if we use a special kind of
microscope (called ’electron microscope’). They are small bundles of protein. Viruses are not
even complete cells, so they cannot carry out reproduction by themselves. They must take
over a host cell, usually a plant or animal cell. The virus uses the host’s cell’s ’system’ to
make copies of itself. Many illnesses are caused by viruses.
3. Fungi
Fungi are a group of plant-like organisms, but not all of them are microscopic. For example,
mushrooms are a type of fungus; other types are yeats and moulds.
Understand the causes of infection
1.1 Identify the differences between bacteria, viruses, fungi and parasites
Bacteria, viruses, pathogenic fungi and parasites are all examples of micro-organisms that can
cause infection.
1. Bacteria
Bacteria are the most common cause of infection in the health care setting.
Most bacteria consist of only one cell and reproduce by dividing in half. They often group
together to form colonies. Scientists classify and name them in many different ways, for
example, by their shapes or by the way they stain.
By their shape bacteria can be:
round – they are called cocci
spiral-shaped – they are called spirilla, or
rod-shaped – they are called bacilli
It is very interesting, for example, if I could hear ’Staphylococcus’, I would know that the
person has an infection caused by a round bacterium, because of the word: ’coccus’.
Bacteria have two types:
aerobic bacteria need oxygen to live, while
anaerobic bacteria die if oxygen is present
Bacteria feed themselves by making their food with the use of sunlight and water. The human body
consists of lots of ’friendly’ bacteria, which protect us from dangerous ones by occupying places in the
body. We would not be able to live without them.
Most bacteria, that can cause illness need a warm, moist and dark environment, as well as a
source of nutrition in order to grow (the inside of the human body can be a perfect place for
them).
2. Viruses
Viruses are the smallest of all microbes. We can see them if we use a special kind of
microscope (called ’electron microscope’). They are small bundles of protein. Viruses are not
even complete cells, so they cannot carry out reproduction by themselves. They must take
over a host cell, usually a plant or animal cell. The virus uses the host’s cell’s ’system’ to
make copies of itself. Many illnesses are caused by viruses.
3. Fungi
Fungi are a group of plant-like organisms, but not all of them are microscopic. For example,
mushrooms are a type of fungus; other types are yeats and moulds.
