BIOL 3053 Lecture 11: Topic 11- Microbial Mechanisms of Pathogenicity
12 Apr 2016
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Document Summary
Pathogenicity- the ability of an organism to cause disease (i. e. harm the host) Virulence- the degree or extent of pathogenicity exhibited by an organism. To cause a disease, a pathogen must: gain access to host: portals of entry, attach to host cells: adherence, penetrate host defenses, cause damage to host cells and tissues, portals of entry. Mucous membranes: respiratory tract (v. imp), gi tract, urogenital tract, conjunctiva. Most pathogens enter by the respiratory tract and gi tract. Respiratory tract- droplets are inhaled by nose and mouth. Gi tract from food, water, fingers; eliminated in feces, can infect others via water, food. Some organisms can penetrate: conjunctivitis, trachoma, ophthalmia neonatorum. Skin- largest organ; important defense; some microbes enter via hair follicles, sweat gland ducts, cuts, wounds. Parenteral route- deposition directly into tissues: bites, punctures, injections, wounds, surgery. A preferred portal of entry is often a pre-requisite for disease: adherence to host cells. Pathogens have adhesins: bind to host cell surface receptors.
