In 1922 Fleming discovered an antiseptic compound capable of killing and dissolving certain bacteria ( * ) which he called "lysozyme” ( * * )
Many animals have this protein: cat, human, dogs, it can even be found in the eggs ( * * * ). All mammals do.
This protein is widely distributed in the animal body, but is found in high concentration in saliva, blood, tears and duodenal (from the small intestine) secretions.
Epstein and Chain' of Oxford University (dunno the date) have confirmed the antiseptic effect of lysozyme by identifying the lysozyme-susceptible substrate in bacterial cells.
The antibacterial properties of saliva where studied later on dogs. It showed that the maternal grooming and in licking of wounds after birth helps prevent the infection of the wounds, but that not all types of bacteria are affected (Hart BL, Powell KL)
However the lysozyme can not dissolve the bacterial compounds completely if it is alone. The acidulation of the saliva after swallowing (in the stomach) improves the antiseptic effect of the lysozyme. Another enzyme, the Trypsin which is a protease (it cuts proteins) is capable of dissolving different parts of the bacterial cell. Complete lysis, however, is affected by a combined action of these two enzymes.
Saliva can prevent the infection but it can not cure anything: British bacteriologists have shown that its bactericide effect depends A LOT on the composition of the cell wall of the bacteria.
( * ) such as Escherichia coli, Staphylococcus aureus, Bacillus anthracis, and Candida albicans. The GRAM+ bacteria are the most affected due to the structure of their cell wall. Follow this link if you do not know what the GRAM test is: http://en.wikipedia.org/wiki/Gram_staining
( * * ) The “lys” part of the word comes from the ancient Greek: λύσις (lusis) which means “dissolve”. The other mart of the word “zyme” is the end of “enzyme”.
( * * * )As an example: A COMPARISON OF LYSOZYME PREPARATIONS FROM EGGWHITE,CAT AND HUMAN SALIVA. By E. A. H. ROBERTS,'
B. G. MAEGRAITH,2 and H. W. FLOREY. From the Sir William
Dunn School of Pathology, Oxford.