The processes which lead to disease are complex and have many contributing factors both internal and external. This article will provide an overview of bacterial pathogenesis and its contributions to the development of disease within a host organism.
Pathogenicity – An overview.
A pathogen is a term that refers to a microorganism that causes disease in an organism. Pathogenicity is the ability of the pathogen to produce disease. Pathogenicity is expressed by microbes using their virulence, or the degree of the microbe’s pathogenicity.
Genetic, biochemical, and structural features that lead to the ability of the pathogen to cause disease are known as its determinants of virulence. Genetic and molecular factors play a large part in a microorganism’s pathogenicity.
The relationship between host and pathogen is dynamic – each modifies the function and activities of the other. The relationship and, therefore, the degree to which disease progresses in the host organism is determined by the pathogen’s resistance and the resistance and susceptibility of the host organism, largely in part due to the effectiveness of the host’s defense mechanisms.
Bacteria can largely be organized into three groups. Frank or primary pathogens are considered to be probable agents of disease. Opportunistic pathogens become pathogenic following the perturbation of a host’s defense mechanisms (for example by wounds, aging, and disease.) Finally, there are nonpathogens, such as Lactobacillus acidophilus, which are present naturally within the host and rarely or never cause disease.