What do microbes do?

Microbes play an important role in disease. Here, we will examine the fact that most microbes are not harmful – in fact, they have a variety of other roles in daily life.

In the environment

• Break down and recycle organic material
• Synthesise nutrients required for plant growth
• Produce oxygen through photosynthesis
• Provide the basis of the food chain

In the body

• Prevent overgrowth/colonisation
• Catabolise dietary components
• Modulate/regulate the immune system
• Synthesise vitamins
• Promote intestinal motility

In industry

• Fungi (yeast) are used to make beer, wine, cheese, and other fermented products
• Used to remove hazardous pollutants from industrial waste
• Used to produce certain drugs (insulin, penicillin, etc.)

Microbes and disease-causing mechanisms

Some microbes are disease causing (pathogenic) and others are not.

The first step in causing disease is transmission of the microbe. Pathogens cause symptoms which allow them to spread (coughing, diarrhoea, etc), but can also create a carrier to aid spread.

Routes of transmission include:

• Airborne transmission – coughing or sneezing
• Close or indirect contact – kissing/sexual activity or touching contaminated surfaces/sharing utensils
• Animals/insect – bite or contact
• Food and water

If a microbe is pathogenic, there are various degrees of pathogenicity, known as virulence.