Chapter 13

1. Chapter 13 Inflammation, Infection, and Immunity

2. 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.

3. 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.

4. 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

5. 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

6. 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

7. Figure 13-2

8. 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

9. Figure 13-1

10. 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)

11. 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

12. 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

13. 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

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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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)

23. 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

24. 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

25. 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

26. 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

27. 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 Trypanosomagambiense (sleeping sickness) Infections often spread by food or water contaminated by human or animal feces

28. 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

29. 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

30. 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

31. 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

32. 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

33. 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)

34. 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

35. 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

36. Figure 13-3

37. 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

38. 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

39. 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

40. Bioterrorism The intentional use of microorganisms to cause death or disease

41. Immunocompromised Patients Decreased immunity to infection; are at increased risk for bacterial, fungal, parasitic, and viral infections

42. 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

43. 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

44. 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

45. 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

46. 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

47. Figure 13-4

48. 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

49. 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

50. 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