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Chapter 13
Inflammation, Infection,
and Immunity
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Skin and Mucous Membranes
• The body’s first line of defense
• Protective covering; secretes substances that inhibit
the growth of microorganisms
• Sweat glands secrete lysozyme, an antimicrobial enzyme
• Sebaceous glands secrete sebum, which has antimicrobial
and antifungal properties
• Acidic secretions from skin and mucosa of GI and GU
systems inhibit growth of many pathogenic organisms
• Secretions from mammary glands and the respiratory and
GI tracts contain immunoglobulin; also clean up
phagocytes
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Skin and Mucous Membranes
• Surfaces colonized by “normal” bacterial flora:
prevent pathogens (disease-causing
organisms) from entering the body
• Cilia in respiratory tract, motility of the GI tract,
and sloughing of dead skin distribute and
remove microorganisms, preventing their
overgrowth and invasion
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Phagocytosis and Inflammation
• The second line of defense
• Helps rid body of invading microorganisms
• White blood cells (leukocytes): colorless cells that are able
to phagocytose (ingest) bacteria that can cause infection
when they invade the body
• Measuring the number of these cells indicates severity of
infection
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Figure 13-2
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The Inflammatory Process
• A series of cellular changes that signal the
body’s response to injury or infection
• May be caused by
• Physical agents
• Excessive sunlight, x-rays
• Chemical stimuli
• Insect venom, other chemicals
• Biologic agents
• Bacteria, viruses
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Figure 13-1
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The Inflammatory Process
• Inflammation: literally “the fire within”
• This descriptive phrase illustrates the four
classic manifestations of inflammation
•
•
•
•
Rubor (redness)
Calor (heat)
Tumor (swelling)
Dolor (pain)
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Actions in the Inflammatory Process
• Hemodynamic changes
• Dilation of the capillary bed
• Increases blood flow to the area
• Warmth and redness at the site of inflammation
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Actions in the Inflammatory Process
• Increased capillary permeability
• Chemical mediators cause leukocytes to line the
small blood vessel walls near the inflammatory site
• Cells pass through the walls; inhabit inflamed area
• Ingest and carry away bacteria and other foreign
substances
• Permeability of these vessels causes protein-rich
fluid to flow through vessel walls into the interstitial
space
• Collection of fluid is responsible for the swelling
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Chemical Mediators
• The hemodynamic changes and vascular
permeability occur with the help of several
chemical mediators
• Prostaglandins, histamine, and leukotrienes
• Powerful substances found in various body tissues;
liberated during the inflammatory process
• Cytokines and eicosanoids
• Cause blood and blood vessel changes
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Kinin System
• Produces bradykinin, which also mediates
blood vessel dilation and permeability
• Produces pain, another classic sign of
inflammation
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Complement System
• Especially important in immunologically
mediated reactions involving antigen-antibody
complexes
• Causes massive release of histamine and other
substances that produce marked vasodilation,
vascular permeability, and smooth muscle
contraction
• These cellular changes produce classic signs of
anaphylactic shock: hypotension, swelling, and
bronchoconstriction
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Anti-Inflammation
• Cortisol
• Hormone produced by the adrenal cortex
• Anti-inflammatory substance that slows the release
of histamine, stabilizes lysosomal membranes, and
prevents the influx of leukocytes
• Result is to impede the inflammatory process
• Protects body from excessive or prolonged
inflammation
• Drugs (such as corticosteroids) that mimic cortisol
often used to treat inflammatory conditions
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Signs and Symptoms of Inflammation
• Local inflammation
• Produces the classic signs of heat, swelling,
redness, and pain, all of which result in loss of
function
• Systemic inflammation
• Fever, headache, muscle aches, chills, sweating,
and leukocytosis
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Wound Healing
• Tissue repair and regeneration set in motion
from the beginning of the inflammatory process
• Process speed depends on type of tissue
injured, severity of the wound, presence of
infection, and health of the host
• Macrophage cells are produced to clean up
inflammatory debris
• Fibroblasts begin repair process by laying
down elastin and collagen at the edges of the
wound
• These substances gradually migrate to the base,
forming granulation tissue
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Wound Healing
• Epithelial cells migrate over the wound and under the
scab (usually formed of dried blood and fibroblasts)
• The scab falls off
• Damaged cells are replaced by new cells of their own
composition by process of regeneration
• Some tissue regenerates well, other must undergo
repair; may involve replacing injured cells with
connective tissue that will eventually create a scar
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Wound Healing
• Occasionally wound becomes infected or
ulcerated, resulting in tissue loss
• Granulation tissue and capillary buds form at
wound margins; wound eventually filled with
granulation tissue
• Delayed primary closure
• Sometimes the wound bed is too large for the
granulation tissue to fill
• Wound is cleaned and débrided to enhance healing
• When infection is no longer present, wound is sutured
closed
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Infection
• Invasion by microorganisms, multiplication of invading
organisms, and resulting tissue damage
• Inflammation: nonspecific body reaction to tissue
injury; infection: a specific process that causes tissue
injury
• Infection always results in inflammation, but
inflammation may be caused by other processes
• Inflammation precedes infection
• Usually the result of the invasion by organisms
• Caused by a wide variety of microorganisms
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Bacteria
• One-celled microorganisms capable of
multiplying rapidly within a susceptible host
• Classified as gram positive or gram negative
• Classified according to shape
• Round bacteria: cocci
• Groups of two: diplococci
• Clusters: staphylococci
• Chains: streptococci
• Rod-shaped organisms
• Fusiform (with tapered ends)
• Spirochetes (spirals)
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Bacteria
• Classified according to their ability to grow in
the presence of oxygen
• Aerobes
• Will grow in the presence of oxygen
• Anaerobes
• Will not grow in the presence of oxygen
• Each classification highlights a characteristic of
a microorganism that is considered in the
design of an antimicrobial drug to kill or retard
the growth of the organism
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Viruses
• Very small microorganisms that cause significant
morbidity (disease) in humans
• Illnesses range from the common cold to acquired
immunodeficiency syndrome (AIDS); childhood
illnesses (measles, chickenpox); and several forms of
hepatitis
• Visible only with electron microscopy
• Contain strand of genetic material and surrounded by a
protein capsule, but have no cell wall
• Cannot replicate on their own; depend on the
resources of the host cell
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Viruses
• Damage by stimulating antigen-antibody
response in tissues that causes inflammation
and cell destruction
• Because of replication of the virus within the
host cell, seldom possible to kill virus without
harming the host cell
• Explains why relatively few antiviral drugs available
• Current antiviral drugs suppress viral reproduction
or growth so that they decrease the severity or
duration of the infection, but they are not curative
• Prevention (immunizations, hygiene) is still the
best way to combat viral illness
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Fungi
• Vegetable-like organisms that exist by feeding
on organic matter
• Many of these infections are superficial skin
infections that rarely produce serious illness
• Systemic fungal infections caused by
Cryptococcus and Aspergillus species; can be
life-threatening
• Patients with compromised immune systems
(e.g., HIV) are at especially high risk of
acquiring opportunistic fungal infections
• Fungal infections are called mycoses
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Protozoa
• Make up a large group of one-celled organisms
• Those that produce disease in humans include the
Plasmodium species (malaria), Entamoeba
histolytica (amoebic dysentery), Giardia lamblia
(giardiasis, characterized by diarrhea), and
Trypanosoma gambiense (sleeping sickness)
• Infections often spread by food or water
contaminated by human or animal feces
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Rickettsiae
• Between bacteria and viruses in size
• Rods, cocci, or pleomorphic (varied) shapes
• Multiply in cells of animal hosts (e.g., rats and
squirrels); transmitted to humans through flea
and tick bites
• Rocky Mountain spotted fever and typhus
• Diseases caused by rickettsiae tend to be
more prevalent in areas in which sanitation is
poor and rodent and insect populations are not
well controlled
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Helminths
• Parasites (worms) are found in soil and water
and are generally transmitted from hand to
mouth
• Infections occur commonly in the
gastrointestinal tract and may produce mild
abdominal pain and bloating, or they may be
asymptomatic
• Examples: pinworms, tapeworms, and
hookworms
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Mycoplasmas
• Gram-negative, multishaped organisms without
cell walls that are responsible for several
infections in humans
• Responsible for primary atypical pneumonia
and have been linked to Reiter’s syndrome
• Infections usually found in the upper
respiratory tract and most often affect children
and young adults
• Respond well to erythromycin
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Transmission of Infection
• Chain of Infection
• Infection possible only when factors occur in
sequence
1. Causative agent
2. Reservoir
3. Portal of exit
4. Mode of transfer
5. Portal of entry
6. Susceptible host
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Signs and Symptoms of Infection
• Localized infections
• Redness, pain, warmth, swelling, and pus
• Generalized infections
• May not show all signs apparent in localized
infections
• Pain may be mild to severe depending on its
location
• Warmth is generally expressed as fever
• Malaise
• Anorexia
• Prostration
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Types of Infection
• Community-acquired infection
• Acquired in day-to-day contact with the public
• Childhood illnesses, tuberculosis, HIV/AIDS, foodborne illness, sexually transmitted infections
• Prevention and control
• Immunizations, educating food handlers, screening and
early treatment, isolation of infected person, control vectors,
personal measures (condom use, proper hygiene,
especially hand washing)
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Types of Infection
• Hospital-acquired (nosocomial) infection
• Occur within a health care facility; may affect patient
as well as health care worker
• Strains of bacteria in hospital usually more virulent
and often resistant to antibiotics
• Some pathogenic bacteria that are no longer
susceptible to previously effective antibiotics are
found in hospital patients
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Medical Asepsis
• Limit spread of microorganisms
• Often called clean technique
• Change bed linen, sanitize bedpans, use individual
medication cups for each patient and for each
administration, frequent hand washing
• Hand washing
• Most effective method to prevent crosscontamination
• Soiled hands main transmission of nosocomial
infections
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Figure 13-3
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Surgical Asepsis, or Sterile Technique
• Eliminate microorganisms from any object that
comes into contact with the patient
• Includes care techniques that prevent unsterile
surfaces from coming into contact with the
patient, such as during dressing changes
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Standard Precautions
• Infection control guidelines for hospitals and other
health care agencies from Hospital Infection Control
Practices Advisory Committee (HICPAC) and CDC
• For all patients in hospitals regardless of their isolation
status
• Use when you will have contact with a patient’s blood,
bodily fluids, secretions (except sweat), excretions,
broken skin, and mucous membranes
• Use when you have contact with materials that are
soiled or contaminated with bodily fluids or blood
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Transmission-Based (Isolation)
Precautions
• Airborne precautions
• Used with diseases that are spread through the air
• Droplet precautions
• Used with infections that are spread by droplets or
dust particles containing the infectious agent
• Contact precautions
• Used when caring for patients who are infected by
microorganisms that are transmitted by direct (skinto-skin) or indirect contact with contaminated
equipment
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Bioterrorism
• The intentional use of microorganisms to cause
death or disease
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Immunocompromised Patients
• Decreased immunity to infection; are at
increased risk for bacterial, fungal, parasitic,
and viral infections
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Nursing Care of Patients with
Infections
• Urge the patient to consume adequate fluids
• Encourage to consume high-protein, highvitamin diet
• Isolation, if required
• Laboratory tests
• White blood cell count with differential; erythrocyte
sedimentation rate; iron level; cultures of urine,
blood, wound, sputum, and throat
• Administer antibiotic drug therapy
• Hyperbaric oxygen therapy
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Immunity
• Provides resistance to invading organisms;
enables body to fight off invaders once they
have gained access
• Antigen
• Any substance capable of stimulating a response
from the immune system
• Usually foreign; body recognizes it because it’s
different
• Antibodies
• Also known as immunoglobulins
• Proteins are created in response to specific
antigens
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Immunity
• Innate (natural) immunity
• Present at birth; not dependent on a specific
immune response or previous contact with an
infectious agent
• Acquired immunity
• Develops after birth as a result of the body’s natural
immune responses to antigens
• Depends on the proper development and
functioning of B and T lymphocytes
• Developed after direct contact with an antigen
through illness or vaccination
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Immunity
• Leukocytes (white blood cells)
• Key role in immune responses to infectious
organisms and other antigens
• Granulocytes and nongranulocytes
• Thymus and bone marrow
• Participate in the formation and maturation of
immune system cells
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Immunity
• Lymph nodes
• Attack antigens and debris in the interstitial fluid and
produce and circulate lymphocytes
• Spleen
• Filter dead cells, debris, and foreign molecules from
blood
• Liver
• Filters blood and plays a part in the production of
specific immunoglobulins and other chemicals
involved in the immune response
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Figure 13-4
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Nonspecific Defenses Against
Infection
• Innate (natural) immunity
• Present at birth; physical and chemical barriers to
invasion of the body as well as substances that
protect and repair tissues and stimulate the body to
fight off disease
• Physical and chemical barriers, inflammation, and
phagocytosis are nonspecific defenses against
infection
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Specific Defenses Against Infection—
The Immune Response
• Antibody-mediated immunity
• First-line defense: B lymphocytes and the production of
antibodies in response to specific antigens
• Humoral immune response initiated when an antigen binds to
a special receptor on a B lymphocyte
• Results in antibodies that seek out and “stick to” specific
antigens in the body
• Forms antigen-antibody complexes, which are then targeted
for cleanup by neutrophils and macrophages
• Formation of these complexes activates complement and
intensifies T-lymphocyte activity
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Specific Defenses Against Infection—
The Immune Response
• Cell-mediated immunity
• A delayed response to injury or infection because of
time needed for migration of T cells and production
of substances that enhance the immune response
and influence the destruction of antigens
• Fights most viral or bacterial infections and hinders
the growth of malignant cells
• This process also launches an attack on
transplanted tissue or organs in the body
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Immunodeficiency
• Etiology and risk factors
• Body unable to launch an adequate immune
response and is at great risk for infection
• Can be congenital or, more commonly, acquired
• Medical treatment
• Congenital immunodeficiency treated with
replacement therapy of the immune component
• Acquired immunodeficiency is treated by correcting
the underlying condition
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Immunodeficiency
• Nursing care
• Prevent infection
• Encourage adequate nutritional intake
• Perform good skin, mouth, perineal, wound, and
IV site care; assess for signs of infection
• Encourage patients to turn, cough, and breathe
deeply
• Protective (compromised host) isolation may be
necessary
• Patient education on risks and signs of infection
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Hypersensitivity and Allergy
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Hypersensitivity and Allergy
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Hypersensitivity and Allergy
• Medical treatment
• Antihistamines, bronchodilators, corticosteroids,
topical lotions and ointments
• Testing to determine specific allergens
• Desensitization
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Hypersensitivity and Allergy
• Nursing care
• Document all allergies, symptoms they cause, and
any treatment currently used
• Education is important for all patients with allergies
• Specific allergens, limiting exposure to or avoiding
allergens, the proper use of medications such as inhaled
bronchodilators, and the actions and side effects of drugs
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Anaphylaxis
• Etiology and risk factors
• Life-threatening; can quickly deteriorate into shock,
coma, and death
• Histamine released causes bronchospasm,
vasodilation, and increased capillary permeability,
which causes fluid to leave the circulation and enter
the tissues, causing shock from hypovolemia
• Signs and symptoms of anaphylaxis include anxiety,
wheezing and difficulty breathing, cyanosis, hives,
facial edema, arthralgia, and hypotension
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Anaphylaxis
• Medical treatment
• Oxygen, intravenous epinephrine, aminophylline,
diphenhydramine, and corticosteroids
• Dopamine to raise blood pressure; nebulized
bronchodilator to relax bronchi and improve
ventilation
• Nursing care
• Administer prescribed drugs, including oxygen, and
monitor intravenous fluids
• Monitor respirations, color, heart rate, and oxygen
saturation until the patient is fully recovered
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Autoimmune Diseases
• Etiology and risk factors
• Immune system reacts against and destroys its own
tissues
• Initiated when tissue injury, infection, or malignancy
• Genetic factor: autoimmune diseases tend to be
familial
• Can involve any tissue or organ system
• Causes injury in three ways
• The effect of antibodies on cell surfaces
• Through the deposit of antigen-antibody complexes
• Through the action of sensitized T cells
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Autoimmune Diseases
• Medical treatment
• Corticosteroids and nonsteroidal anti-inflammatory
drugs (NSAIDs) are used to treat inflammation
• Immunosuppressive therapies may be tried to
moderate the autoimmune response
• Nursing care
• Adequate rest, maintenance of optimal hydration
and nutritional status, and prevention of infection
• Supportive atmosphere important to enhance the
patient’s coping skills and promote emotional health
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