Sterile Procedures
LESSON 1: Communicable Diseases
1-3
1-3. CLASSIFICATION OF PATHOGENS
a. Infectious Agents. Infectious (pathogenic) agents of one kind or another are everywhere that life exists. They inhabit the air, soil, and water. In the body of humans and animals, they inhabit waste products, skin, respiratory tracts, and alimentary tracts. Agents capable of harming man include bacteria, viruses, and fungi. The primary basis for the development of infection is the growth of bacteria within the wound itself. All injuries in which the skin has been penetrated are contaminated by bacteria. Following are some of the types of pathogens.
(1) Bacteria. Bacteria are microscopic one-celled plant organisms. The group names sometimes describe the infection. The most common are named below.
(a) A staphylococcus is a pyogenic (pus-producing), spherical-shaped form of bacteria. It is the most common cause of localized infection in which pus is present.
(b) Streptococcus is also a pyogenic, spherical-shaped form of bacteria.
(c) Bacilli is a term applied to rod-shaped bacteria.
(2) Viruses. Most viruses are very small microscopic protein bodies. They are neither plant nor animal. Viruses are capable of multiplying only in the presence of living cells and are normally separated into subgroups according to the type of host they infect--bacterial viruses, animal viruses, and plant viruses.
(3) Fungi. Fungi are a low order of plant life that lack chlorophyll, such as toadstools, yeast, and molds. An example of a condition caused by a fungus is athlete's foot (tinea pedis).
b. Development of Infection. Bacteria multiply and increase in numbers very rapidly; however, wounds of less than 4 hours old are considered to contain bacteria that have not begun to grow. Those wounds from 4 to 8 hours old are known to contain bacteria that are actively growing in the tissues on the surface or in the
depths of the wound. In injuries more than 8 hours old, the bacteria have usually invaded adjacent
tissue and may have invaded along the lymphatics or the bloodstream. The infectious agents not only multiply rapidly and invade adjacent tissue, but they also give off poisonous products called toxins.
(1) Surface. Local infection confined to immediate tissue of the wound is considered to be surface infection.
(2) Regional. Infection that spreads along the lymphatics is considered as regional.
(3) Systemic. If the invasion is by way of the bloodstream, it is systemic infection.
