Gentamicin protection assay

The assay is based on several observations made in the 1970s, in which the ability of internalized bacteria to avoid killing by antibiotics was reported.

Many species of Shigella (causes bacillary dysentery), Salmonella (typhoid fever), Mycobacterium (leprosy and tuberculosis) and Listeria (listeriosis), to name but a few, are intracellular.

The assay is performed in plastic microtiter plates, which are commonly used in laboratories for culturing eukaryotic cells.

After infection gentamicin is added to the plates, and they are incubated for an hour, allowing the antibiotic to kill all bacteria that were not able to penetrate the cells and remained outside.

The contribution of specific genes or proteins to the bacteria's ability to invade cells can be easily assayed using this method.

The antibodies emit fluorescent, colored light, and the results of this assay are viewed under the microscope.