What are some mechanisms by which pathogenic bacteria cause diseases? Why is this knowledge important?

Pathogenic bacteria have characteristics known as virulence factors, which help them to parasite their hosts. Some bacteria have fimbriae, cilium-like structures that hook the bacterial cell onto the host tissue. Some bacteria are specialized in intracellular parasitism. Others secrete toxins, molecules that cause disease. In some cases, bacterial population growth causes food poisoning by toxins. Generally, bacterial disease is caused by bacterial population growth resulting in the invasion and destruction of tissues or by bacterial toxins that contaminate an organism.