There are various different ways that pathogenic bacteria can damage and kill human cells, but one of the most common is by the production of toxic molecules. These small molecules are made inside the bacterial cell, the protein chain built using the DNA template and then often modified within the cell before being secreted directly into, or in the general direction of, human cells. A recent paper in PLoS Pathogens took a look at some of these toxic molecules produced by C. difficile, a human pathogen that infects the human colon and is showing worrying levels of antibiotic resistance.
"Success is not measured by what you accomplish but by the opposition you have encountered, and the courage with which you have maintained the struggle against overwhelming odds." -- Orison Swett Marden