University of Kerbala / College of Nursing
Fundamentals of Nursing Department
Subject: Fundamentals of Nursing I
Asepsis and infection control
Assistant Instructor: Hassan Abdullah athbi
Stages of infections:
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An infection progresses through the following phases:
1) Incubation period: the time between the entry of infectious agents in the host
and the onset of nonspecific symptoms. During this time the infectious agent
invades the tissue and multiplies to produce infection.
2) Prodromal stage: the time from the onset of nonspecific symptoms until
specific symptoms begin manifested.
3) Full stage of illness: the time when the client has specific signs and symptoms
of an infectious disease.
4) Convalescent period: the time from the beginning of the disappearance of acute
symptoms until the client returns to the previous state of health.
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The body's defense against infection:
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1. Nonspecific defenses: protect the person against all microorganisms, regardless
of prior exposure. Nonspecific defenses include:
a. Anatomic and physiological barriers:
 Intact skin and mucous membrane are the body's first line of defense against
microorganisms.
 Cilia in the respiratory passage has protective mechanisms against infection,
 Tears in the eye has protective mechanisms against infection,
 Acidity of the stomach has protective mechanisms against infection,
 Resident flora of the large intestine help to prevent the establishment of
microorganisms, peristalsis also tend to move microbes out of the body,
 The vagina also has natural defenses against infection (low pH 3.5-4.5 of
vaginal secretions inhibits the growth of many disease producing
microorganisms),
 It is believed that the urine flow has a flushing and bacteriostatic action that
keep the bacteria from ascending the urethra.
b. Inflammatory response:
Inflammation: Is a local and nonspecific defensive response of the tissue
to injurious or infectious agent. It is characterized by:
1. Redness (erythema): result from increase blood flow to the area.
2. Heat: results from increase blood flow and metabolism in the area.
3. Pain: result from increased pressure by the accumulating fluid on nerve
endings and the irritating chemical mediators in the area.
4. Swelling(edema): result from fluid and electrolytes entering the tissues
from the circulatory system.
5. Loss of function: result from both pain and swelling.
6. Pus (purulent exudates): resulting from infection, is a secretion made up of
white blood cells, dead cells, bacteria, and other debris.
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Fundamentals of Nursing I
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University of Kerbala / College of Nursing
Fundamentals of Nursing Department
Subject: Fundamentals of Nursing I
Asepsis and infection control
Assistant Instructor: Hassan Abdullah athbi
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Stages of inflammatory response:
a. Vascular and cellular responses: At the start of the first stage of
inflammation, blood vessels at the site of injury constrict. This is rapidly
followed by dilatation of small blood vessel , thus more blood flows to the
injured area as a result of vasodilatation at the site of injury that’s responsible
for signs of redness and heat .Vascular permeability increases at the site with
dilation of the vessels in response to cell death, the release of chemical
mediators (serotonin and prostaglandin), and the release of histamine. Fluid ,
protein, and leukocytes (WBCs) leak into the interstitial spaces, and the signs of
inflammation (swelling, and pain) appear.
b. Exudates production: consisting from fluid that escaped from the blood
vessels, dead phagocytic cells, and dead tissue cells and products that’s release.
c. Reparative phase: involves the repair of injured tissues by regeneration or
replacement with fibrous tissue (scar) formation.
2. Specific defenses: involve the immune system, are directed against identifiable
infectious agent.
Factors increasing susceptibility to infection:
1. Age (newborns and older adults have reduced defenses against infections).
2. Heredity (some may be deficient in serum immunoglobulin).
3. Level of stress (stressors elevated blood cortisone, prolonged elevation of blood
cortisone decrease anti-inflammatory responses, depletes energy stores, lead to
state of exhaustion, and decreases resistance to infection).
4. Nutritional status ( the ability of synthesize antibodies may be impaired by
inadequate nutrition).
5. Current medical therapy (for example anticancer may depress bone marrow
function resulting in inadequate production of WBCs).
6. Preexisting disease processes.
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Fundamentals of Nursing I
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