Concepts of Infection, Inflammation, and Immunity

Concepts of Infection, Inflammation, and Immunity

Overview

  • Instructors: Angela Archer MSN, RN

  • Institution: Tulsa Community College

Objectives

  • Define the concepts of immunity, inflammation, and infection.

  • Distinguish between Innate Immune Response (CMI) and Adaptive Immune Response (AMI) in terms of:

    • Triggers

    • Cell Types

    • Responses

    • Duration of Protection

  • Interpret laboratory findings to assess the patient's risk for an immunity issue or increased risk for infection.

  • Identify common assessment findings associated with local and systemic infections, including signs and symptoms of inflammation.

  • Identify common risk factors for infections.

  • Describe the process of inflammation.

Infection, Inflammation & Immunity

  • Immunity = protection

  • Inflammation = response

  • Infection = invasion and colonization

Immunity

  • Defined as the body's defense system:

    • Recognizes threats

    • Destroys threats

    • Remembers threats

Natural Defense Barriers of Immunity

  • First Line of Defense - Innate Immunity includes:

    • Skin: acts as a barrier, for example, sebum shedding.

    • Mouth and Eyes: mechanical and chemical barriers.

    • Respiratory Tract: mucous membranes trap pathogens.

    • Urinary Tract and Gastrointestinal Tract: involve mechanisms such as acidity and enzyme activity.

Immunocompetence

  • Involves:

    1. Inflammation: Initial immune response.

    2. AMI (Adaptive Immune Response): Produces antibodies, involving B-lymphocytes.

    3. CMI (Cell-mediated Immunity): Driven by T-lymphocytes, involves white blood cells (WBCs) and cytokines.

  • These three processes are essential for being immunocompetent against pathogens.

Lifespan Considerations: Older Adults

  • Normal aging leads to:

    • Decreased immune response.

    • Lower resistance to infections.

    • Higher prevalence of autoimmune diseases.

    • Often atypical symptoms of infections (e.g., absence of fever).

Inflammation

  • Defined as a protective response to injury or infection.

  • Purpose: To bring blood and immune cells to assist in healing.

Stages of Inflammation

  1. Vascular and Cellular Response: Increased blood flow and immune cell migration to the site.

  2. Exudate Production: Accumulation of fluid and cells, often causing swelling.

  3. Healing Stage: Repair of tissue following the resolution of inflammation.

Acute vs. Chronic Inflammation

  • Acute Inflammation:

    • Occurs within minutes or hours.

    • Typical signs include warmth, redness, pain, loss of function, and edema.

    • Continues until the trauma is neutralized (example: sprained ankle).

  • Chronic Inflammation:

    • Can range from seasonal allergic reactions to chronic autoimmune diseases (e.g., rheumatoid arthritis, osteoarthritis).

    • Causes may include physical, chemical, or biological factors.

Inflammation vs. Infection

  • Key distinction:

    • Inflammation does not always indicate infection.

    • Infection leads to inflammation, but inflammation can occur without an infection.

Nursing Assessment of Inflammation

  • Approach assessment based on the body area involved, utilizing:

    • Laboratory data.

    • Patient observation and interviews.

    • Eating habits and potential stress factors (cortisol production).

    • Functional impairments and systemic manifestations (headaches, body aches, fever >38.0°C / 100.4°F).

White Blood Cell (WBC) Count

  • Indicator of infection, immunity, or immunosuppression:

    • Normal range: 5,000-10,000 cells/mm³.

    • WBC > 10,000: Indicates infection.

    • WBC < 5,000: Suggests immunosuppression.

WBC Differential Types:

  • Neutrophils (Segs, or Polys)

  • Lymphocytes

  • Monocytes

  • Macrophages

  • Eosinophils

  • Bands (immature neutrophils)

  • Basophils

  • Mnemonics to remember: "Never Let Monkeys Eat Bad Bananas."

Laboratory Basics

  • Normal WBC count: 5,000−10,000ext/mm35,000 - 10,000 ext{ / mm}^3

  • ESR (Erythrocyte Sedimentation Rate): Affects measurement of inflammation; a result >20 mm/hr suggests inflammation.

  • CRP (C-reactive Protein): Produced in the liver in response to inflammation; a result >10 mg/L indicates an inflammatory state.

  • Glucose levels: Normal range is 74−10674 - 106; elevated during inflammation or infection.

Concept of Infection

  • Definition: Infection refers to the invasion of pathogens into the body.

Types of Infection

  • Acute Infection: Resolves within a short period.

  • Chronic Infection: Lasts more than 12 weeks.

Susceptible Hosts

  • Populations at higher risk include:

    • Elderly

    • Infants

    • Immunocompromised individuals

    • Generally, anyone can be susceptible.

Common Pathogens

  • Types:

    • Bacteria

    • Viruses

    • Fungi

    • Parasites

Chain of Infection

  • Infection can develop if this chain remains uninterrupted:

    • Portal of Entry: Mouth, nose, eyes, cuts in skin.

    • Mode of Transmission: Direct contact, indirect contact, vectors.

    • Reservoir: Can include people, animals, soil, food, and water.

    • Portal of Exit: Coughing/sneezing, bodily secretions, and feces.

Phases of Infection

  1. Incubation Period: Time between exposure to pathogens and the onset of symptoms.

  2. Prodromal Stage: Onset of general symptoms.

  3. Illness Stage: The period when disease-specific symptoms appear.

  4. Convalescence: Recovery period following the illness.

Bacterial and Viral Anatomy

Bacteria Cell Anatomy

  • Key components include:

    • Ribosome

    • Capsule

    • Cell wall

    • Pilus

    • Flagellum

Anatomy of a Virus

  • Features crucial for targeting treatments include:

    • RNA enclosed in protein

    • Spike protein for cell entry

    • Lipid membranes

    • Nucleoid (DNA component)

    • Cell membrane encapsulating the virus.

Virus vs. Bacteria Differences

  • Highlight differences between these two pathogen types.

Systemic Infection: Influenza

  • Influenza (Flu):

    • Highly contagious viral infection of the respiratory epithelium.

    • Main types: Type A and B.

    • Risk factors include age and health status.

    • Prevention: Immunizations and antiviral drugs (e.g., oseltamivir (Tamiflu)).

    • Management: Treat symptomatically; antibiotics may be used for secondary bacterial infections, e.g., pneumonia. Increased mortality rates may occur due to complications.

Community Acquired vs. Healthcare Acquired Infections

  • Community Acquired Infection: Acquired through daily interactions (e.g., pneumonia, flu, COVID-19).

  • Healthcare (Hospital) Acquired Infections (HAIs):

    • Considered preventable, occurrences of which must be minimized.

    • Most common HAIs: Catheter-associated urinary tract infections (CAUTIs).

    • CAUTIs occur primarily when foley catheters are placed unnecessarily.

    • Hospital strains of bacteria often show higher virulence and antibiotic resistance (e.g., ESBL, VRE).

Nursing Assessment & Clinical Judgment: Assessing the Patient

  • Assessment Guidelines:

    • Conduct a thorough physical assessment focusing on the status of the patient.

    • Review travel history, laboratory diagnostics, and presence of medical lines or surgical incisions.

    • Consider emotional and psychological stress factors.

    • Evaluate immunization history and conduct urine assessments for abnormalities in color or odor.

    • Monitor vital signs for changes (high heart rate, temperature, blood pressure, respiration).

    • Review medications (e.g., steroids) affecting immune response.

Nursing Care of Patients with Infection

  • Keep patients safe: Regular assessments of the patient and lab results every shift or as needed.

  • Prevent infection transmission: Emphasize the importance of hand hygiene.

  • Provide holistic care: Address psychosocial and physical needs of patients and their families.

  • Administer treatments: Medications, antibiotics, and other interventions as ordered.

Medications Used in Treating Infections/Fever/Pain

  • Analgesics & Antipyretics: Used to manage fever and pain.

  • NSAIDs: Provide analgesic and antipyretic effects.

  • Broad-Spectrum Antibiotics: Effective against multiple pathogens, treats pneumonia and skin infections, including urinary tract infections (UTIs).

  • Antivirals: Target viral replication and inhibit the progression of viral infections.

Special Considerations for Infection Control

  • Apply preventive measures for all patients regardless of infection status.

  • Emphasize specific precautions for infections spread via air particles (e.g., COVID-19).

Cultural Considerations for Patients with Infections

  • Recognition that patients from diverse backgrounds may have unique beliefs and methods of treating diseases and infections.

  • Importance of respecting patient privacy related to their health practices and protection mechanisms (e.g., prayer/ritual items).

Quiz Question

  • Which nursing action best breaks the chain of infection?

    • A. Antibiotics

    • B. Hand hygiene

    • C. Oxygen

    • D. Pain medication

References

  • Ignatavicius, D., Workman, M., Rebar, C, & Heimgartner, N. (2024). Medical Surgical Nursing: Concepts for Interprofessional Collaborative Care, 11th ed. Elsevier.

  • Potter, P., Perry, A., Stockert, P., & Hall, A. (2026). Fundamentals of Nursing, 12th Edition. Elsevier.