Inflammation, Infection, and Immunity Chapter 13 Inflammation, Infection, and Immunity

Learning Objectives Describe physical and chemical barriers. Describe how inflammatory changes act as bodily defense mechanisms. Identify the signs and symptoms of inflammation. Discuss the process of repair and healing. Differentiate infection from inflammation. Discuss the actions of commonly found infectious agents. Describe the ways in which infections are transmitted. Identify the signs and symptoms of infection. Compare community-acquired and nosocomial infections.

Learning Objectives Discuss the nursing care of patients with infections. Describe the Centers for Disease Control and Prevention (CDC) Standard Precautions guidelines for infection control. Describe the CDC isolation guidelines for Airborne, Droplet, and Contact (Transmission-Based) Precautions. Describe the immune response. Identify the organs involved in immunity. Compare natural and acquired immunity. Differentiate between humoral (antibody-mediated) and cell-mediated immunity. Describe the nursing care of patients with immunodeficiency and of patients with allergies. Describe the process of autoimmunity.

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

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

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 What are the two types of leukocytes that are especially suited for this purpose?

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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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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) These signs are the direct result of several related actions that occur when the inflammatory process is initiated. What actions are involved in the inflammatory process?

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

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 What is pavementing? Swelling may also produce pain.

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

Kinin System Produces bradykinin, which also mediates blood vessel dilation and permeability Produces pain, another classic sign of inflammation

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

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

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 Fever is probably caused by pyrogens or by defense mechanisms that are liberated during phagocytosis, or by bacterial endotoxins, antigen-antibody complexes, and certain viruses. What is leukocytosis?

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

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 The age and general health of the person affects how rapidly the regeneration and repair process occurs. The healing process can be delayed in the older adult as a result of decreased tissue elasticity and decreased blood supply. What deficiencies may cause a delay in wound healing?

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

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

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) What may protect the bacteria from phagocytosis? Classification of bacteria as either gram-positive or gram-negative depends on their ability to take up and retain a violet-colored solution called a Gram stain. Gram-positive bacteria retain the stain. Gram-negative bacteria can be decolorized and counterstained pink.

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 What is an example of how a bacteria classification may affect what antimicrobial drug is used?

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

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

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 What are some examples of fungal organisms? Because fungi tend to form spores that are resistant to many antiseptics and disinfectants, they are difficult to treat. Both systemic and topical antimycotic drugs are used to treat fungal infections.

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 Pneumocystis jiroveci is a protozoal infection that was relatively rare before the onset of the HIV/AIDS epidemic. What causes patients with HIV infection to be at risk for pneumocystic pneumonia?

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

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 What are the symptoms of pinworms? Tapeworms? Hookworms? Tapeworms can be found in the gastrointestinal tract. Hookworms often enter an individual through the soles of the feet and migrate throughout the body.

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 Reiter’s syndrome is a multisystem inflammatory disease that may be associated with urethritis, conjunctivitis, and pharyngitis. What are pleuropneumonis-like organisms?

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 Causative agents are the microorganisms that are present in sufficient number and virulence to damage human tissue. Areas in which organisms can pool and reproduce are called reservoirs. Portal of exit refers to the route by which the infectious agent leaves one host and travels to another. Mode of transfer refers to the means by which a microorganism is transported to a host. Portals of entry are the doorways or pathways into the host. Microorganisms must become implanted into a susceptible host. What are examples of each of these factors?

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 Once an individual becomes infected with a pathogen, symptoms may or may not be apparent. What is a subclinical infection? Asymptomatic carriers may inadvertently infect others.

Types of Infection Community-acquired infection Acquired in day-to-day contact with the public Childhood illnesses, tuberculosis, HIV/AIDS, food-borne 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) Many viral infections are pervasive in society and occur at predictable times of the year. When are common childhood illnesses most prevalent? Food-borne illnesses? Poverty, low immunization rates, overcrowding, unsanitary living conditions, and resistant strains of pathogens are at least partially responsible for the increase in infectious diseases that were once well controlled.

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 Vancomycin-resistant enterococcus (VRE) is one example; the incidence of vancomycin resistance in patients with a nosocomial enterococcal infection is rapidly increasing. What measures may prevent the spread of VRE? Iatrogenic infections are caused by the treatment given the patient.

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 cross-contamination Soiled hands main transmission of nosocomial infections What three things should be used for good hand washing? The use of antimicrobial soaps is also recommended when working with patients who are more susceptible to infection, such as premature infants or immunocompromised patients.

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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

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 The current guidelines, called standard precautions, combine the major features of universal precautions and body substance isolation precautions. Use standard precautions with all patients, no matter what their diagnosis or infectious status may be. What are the guidelines for the use of standard precautions?

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 (skin-to-skin) or indirect contact with contaminated equipment What are examples of disease spread through the air? Droplets? Contact? Surgical masks filter expired air; respirators such as the HEPA filter respirator and the N95 respirator filter inspired air. Droplets are spread primarily during coughing, sneezing, or talking and during certain procedures such as suctioning and bronchoscopy. Needles, dressings, stethoscopes, bed rails, and doorknobs may become contaminated and cause the spread of microorganisms by contact.

Bioterrorism The intentional use of microorganisms to cause death or disease Methods used to spread agents of bioterrorism are varied and might include powders, aerosols, or contamination of food or water. What are some agents that may be used in bioterrorism? Nurses should be aware of their employing agency’s plans for dealing with public exposure to bioterrrorism agents, including decontamination procedures and personal protective equipment and procedures.

Immunocompromised Patients Decreased immunity to infection; are at increased risk for bacterial, fungal, parasitic, and viral infections Patients receiving chemotherapy and other patients with low white blood cell counts are at increased risk of infection. What diseases may cause a patient to be immunocompromised? The use of standard precautions for all patients and of transmission-based precautions for specific situations should reduce the risk of acquiring infections from other persons and from the environment.

Nursing Care of Patients with Infections Urge the patient to consume adequate fluids Encourage to consume high-protein, high-vitamin 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 Fluid intake is important in the transportation of nutrients to the cells to fight infection. How much fluid intake should a patient have each day? Examples of nursing diagnoses for patients with infections or for patients who are vulnerable to infections include Risk for Infection, Risk for Injury, Impaired Tissue Integrity, Social Isolation, and Disturbed Body Image. Caution patients not to stop taking the medication when they start feeling better.

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 If the immune system is intact and functioning properly, it is able to provide adequate protection from most infections and diseases in a healthy individual. What are some factors that may compromise the immune system? Once the body recognizes a substance as an antigen, natural and acquired defenses are put into action to destroy the invader and prevent disease.

Immunity Innate (natural) immunity Acquired 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 What factors may influence innate immunity? Nonspecific defense mechanisms, including physical and chemical barriers to infection, phagocytosis and the inflammatory process, contribute to natural immunity. Once the body has been exposed to an antigen through illness or vaccination, antibodies develop and retain memory for the antigen. If the body is exposed to the same antigen later, the antibodies can react quickly to fight off disease.

Immunity Leukocytes (white blood cells) Thymus and bone marrow 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

Immunity Lymph nodes Spleen Liver 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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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 Other nonspecific defenses against infection that protect the body include complement, pyrogen, and interferon. How do complement, pyrogen and interferon assist with defense against infections?

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 What are the five classes of antibodies (immunoglobulins)?

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 What three types of cells do T cells include?

Immunodeficiency Etiology and risk factors Medical treatment 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 What is the primary clinical clue to immunodeficiency? Stress, whether physical or emotional, alters the body’s response to disease.

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 What is the single most important measure in prevention? A small increase in body temperature in these patients can be significant and should be reported.

Hypersensitivity and Allergy

Hypersensitivity and Allergy Medical treatment Antihistamines, bronchodilators, corticosteroids, topical lotions and ointments Testing to determine specific allergens Desensitization What are the side effects of antihistamines? Testing is performed by injecting small amounts of allergen under the skin (intradermally) or by pricking the surface of the patient’s skin and monitoring for the degree of wheal-and-flare reaction. Desensitization is aimed at increasing tolerance to the offending agent and decreasing the severity of the allergic response.

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 Never administer any drug to which the patient reports a previous allergic reaction. Where should patient allergies be posted? Patients who are at risk for life-threatening (anaphylactic) reactions should wear a medical alert bracelet that identifies their allergy. Individuals with insect sting allergies should obtain an emergency sting kit and be taught how to self-inject epinephrine.

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 Anaphylaxis is an emergency situation, and the patient’s life depends on rapid intervention. What is the most common cause of anaphylaxis?

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 The best care is to prevent anaphylaxis whenever possible by obtaining a history of allergies and taking precautions to protect the patient from substances (often drugs) that may trigger this reaction.

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 The exact causes and pathology of most autoimmune diseases are poorly understood, but many of these disorders cause severe illness and death. What are examples of autoimmune diseases?

Autoimmune Diseases Medical treatment Nursing care 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