1-1. INTRODUCTION

Infections are prone to develop in wounds of violence. Therefore, the prevention and control of infection is one of the chief problems in emergency medical treatment and care of wounded patients.

The development of infection, particularly in large wounds, increases the period of morbidity since infection produces further destruction of tissue and suppresses the healing process. Infection also has a marked effect on the final result of the injury and the mortality. Tissues destroyed by infection are usually replaced by scar tissue, which may have a harmful effect on function as well as appearance.

1-2. DEFINITIONS

Some of the terms related to infection are defined below:

a. Antibiotic. An antibiotic is a substance produced by microorganisms, which kills bacteria and other microorganisms. It is used in treating infectious diseases.

b. Antiseptic. An antiseptic is an agent that may kill pathogens, but more often retards their growth.

c. Aseptic. Aseptic is a state of being sterile (free from septic material).

d. Contaminated. Contaminated means compromised by the presence of bacteria or harboring pathogenic agents.

e. Infection. An infection is produced by an invasion of disease-producing pathogens which multiple in the body.

f. Malaise. Malaise means body discomfort.

g. Morbidity. Morbidity refers to the condition of being diseased or to the ratio of sick to well persons. This is not to be confused with mortality, which is the death rate.

h. Pathogen. A pathogen is a disease-producing organism.

i. Phagocyte. A phagocyte is a form of leukocyte (white blood cell) that ingests microorganisms or other cells.

j. Septic. Septic refers to something that is affected by pathogens, their toxins, or to something putrid.

k. Septicemia. Septicemia refers to the widespread distribution of infective bacteria through the bloodstream. It is also called “blood poisoning.”

l. Sterile. Sterile means free from live pathogens and other live microorganisms.

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.

1-4. COMMUNICABLE DISEASES

A communicable disease is an illness that can be transmitted from one person to another person, from an animal to a person, or from a person to an animal. Communicable diseases can be divided into the following five groups.

a. Respiratory Diseases. Respiratory diseases are usually transmitted from person to person by discharges from the nose, mouth, throat, or lungs of an infected person. Examples of communicable respiratory diseases include the common cold, influenza (flu), pneumonia, streptococcal throat infection (strep), and tuberculosis (TB).

b. Intestinal Diseases. Intestinal diseases are usually transmitted by food or water that is contaminated by the feces or urine of an infected person or animal. Examples of communicable intestinal diseases include typhoid, cholera, and dysentery.

c. Insect-Borne Diseases. Insect-borne diseases are transmitted from a person to another person or from an animal to a person by insects. Examples of communicable insect-borne diseases include malaria (transmitted by mosquitoes), yellow fever (transmitted by mosquitoes), typhus (transmitted by lice), Rocky Mountain spotted fever (transmitted by ticks), and plague (transmitted by fleas). Ticks and mites are not true insects, but are generally called insects because of their resemblance to true insects.

d. Sexually Transmitted Diseases. These diseases are usually transmitted from person to person by sexual intercourse. Examples include syphilis, gonorrhea (clap), and chancroid.

e. Bloodborne Diseases. For more on such diseases as human immunodeficiency virus (HIV) and hepatitis B virus (HBV) and how to protect yourself against them, see Section III of this lesson.

f. Miscellaneous Diseases. Miscellaneous communicable diseases consist of communicable diseases that do not fall into any of the other five groups. Diseases such as tetanus (lockjaw) and rabies fall into this group.