In an experiment published in the July 2008 issue of Microbial Pathogenesis, researcher looked at the ability of serrapeptase (a protease that breaks down proteins) to prevent infection by the life-threatening Listeria monocytogenes bacterium.

Since surface proteins have been shown to be essential in the attachment and eventual invasion of host cells, they decided to try serrapeptase to see if it could inhibit the process.  Serrapeptase is a protease enzyme that breaks down protein.  They chose serrapeptase because it is already widely used as an anti-inflammatory agent in patients.

They found that treatment of the bacteria with serrapeptase reduced their ability to invade host cells.  Their research showed that surface proteins involved in the attachment of the bacteria to the host were reduced.  They concluded that serrapeptase might be a useful treatment to prevent the initial adhesion of the Listeria batecria in the human gut.

Source:

Protease treatment affects both invasion ability and biofilm formation in Listeria monocytogenes.