During World War I Fleming continued his investigations
into antibacterial substances. Testing the nasal mucus
from a patient with a heavy cold, he found
that it had an inhibitory effect on bacterial growth.
This was the first recorded discovery of lysozyme,
an enzyme present in many secretions including:
tears, saliva, skin, hair, nails and mucus.
Unfortunately, the enzyme was only
effective against small counts of harmless bacteria,
and therefore had little therapeutic potential. (28 lugl 1914 anni – 11 nov 1918 anni)