MICROORGANISMS : Great care must be taken in microbiological experiments, particularly with pathogenic (disease producing) organisms. Many microorganisms which are normally harmless, such as E coli in the intestines, can produce disease in a different habitat. E coli, for example, can cause septicaemia if it finds its way into the bloodstream. The most common sources of microorganisms are cultures, lab animals (including their bedding and litter), dissection material and soil. Routes of entry into the body are as follows:

Inhalation - through the nose and mouth into the respiratory system, also through the eyes via tear ducts to the nose

Ingestion - through the nose and mouth into the digestive system

Penetration - through skin injuries

You will in this section study about the precautionary measures that need to be undertaken while conducting the lab work using microbes.