infection

INFECTION PREVENTION AND CONTROL

Chapter Overview

  • Date: 1/13/2026

  • Focus on the nature of infections and methods of prevention

NATURE OF INFECTION

  • Infection Defined:
      - Occurs when a pathogen invades host tissues and begins to grow.
      - Differentiates from colonization, where microorganisms live in a host but do not invade tissues or cause damage.

  • Communicable Disease:
      - Defined as a disease that can be transmitted from one person to another.

  • Symptomatic vs. Asymptomatic:
      - Symptomatic: Shows signs or symptoms of the disease.
      - Asymptomatic: No visible symptoms despite the presence of the disease.

CHAIN OF INFECTION

  • Components:
      1. Infectious Agent
      2. Reservoir
      3. Portal of Exit
      4. Mode of Transmission
      5. Portal of Entry
      6. Susceptible Host

COMPONENTS OF THE CHAIN OF INFECTION

SUSCEPTIBLE HOST

  • Defined as individuals at risk of infection due to weakened immune systems—includes residents, staff, and visitors.

  • Risk Factors:
      - Elderly individuals may have decreased immune responses.
      - Infections tend to spread quickly in care settings due to close living conditions.

INFECTIOUS AGENT (1)

  • Refers to microorganisms (germs) that can cause infections.
      - Types:
        - Bacteria
        - Virus
        - Fungi
        - Protozoa
      - Normal Flora:
        - Normally existing microorganisms that do not cause disease.
      - Virulence:
        - Describes the ability of a pathogen to produce disease.
      - Impacts on particular groups (immunocompromised, post-surgery).
      - Transient Microorganisms:
        - Attach to skin through contact with contaminated surfaces.
      - Prevention:
        - Hand hygiene is critical—washing hands with soap and water, particularly with pathogens like Clostridium difficile.

RESERVOIR (2)

  • Defined as the environment where microorganisms reside, multiply, and wait for transfer to a host.
      - Common Reservoirs:
        - Animals, humans, insects, food, water, organic matter on inanimate objects.
      - Essential conditions include food, water, oxygen, temperature, pH, and light for survival.

PORTAL OF EXIT (3)

  • The route through which a microorganism exits a host to infect another.
      - Exit Sites Include:
        - Blood
        - Skin
        - Mucous membranes
        - Respiratory tract
        - Genitourinary tract
        - Gastrointestinal tract
        - Transplacental routes (from mother to baby)

MODES OF TRANSMISSION (4)

  • Each pathogen has specific modes of transmission.
      - Preventive Actions:
        - Effective hand hygiene is the best preventive measure.
      - Main Transmission Route in Healthcare:
        - Inadequate handwashing by personnel.
      - Additional routes include contaminated equipment (e.g., stethoscopes, commodes).

PORTAL OF ENTRY (5)

  • Microorganisms enter the body through the same pathways they use to exit.

  • Immunocompromised individuals are at greater risk due to reduced defenses against pathogens.

SUSCEPTIBLE HOST (6)

  • Individual susceptibility to infections is determined by their resistance to pathogens.

  • Factors Affecting Susceptibility:
      - Age, trauma, chronic diseases, nutritional status, smoking.

THE INFECTIOUS PROCESS

  • Risk Precautions:
      - Implement precautions if a patient is at risk of infection to interrupt the infection chain.

  • Signs of Infection:
      - Observe specific signs and symptoms to mitigate the spread.

  • Infection Stages:
      1. Incubation Period:
         - Time between pathogen entry and the start of symptoms.
      2. Prodromal Stage:
         - Initial non-specific symptoms leading to specific symptoms.
      3. Illness Stage:
         - Presence of specific signs and symptoms of infection.
      4. Convalescence:
         - Period when acute symptoms diminish.

DEFENSES AGAINST INFECTION

  • The body has natural defenses that protect against infection, which include:
      - Normal flora
      - Body System Defenses:
        - Vascular and cellular response
        - Inflammatory exudate
        - Tissue repair
      - Inflammation:
        - A defensive response to infection.

HEALTHCARE-ASSOCIATED INFECTIONS (HAIs)

  • Defined as infections acquired by patients during healthcare delivery.

  • Caused primarily by:
      - Invasive procedures
      - Antibiotic administration
      - Presence of multidrug-resistant organisms (MDROs)
      - Breaches in infection control protocols

  • Types of Infections:
      - Exogenous Infection:
        - Infection originating from outside the body.
      - Endogenous Infection:
        - Infection occurring from microorganisms already present in the body.
      - Iatrogenic Infection:
        - Infection resulting from medical examination or treatment.

  • Financial Impact:
      - HAIs are not reimbursed by insurance.

FACTORS INFLUENCING INFECTION PREVENTION AND CONTROL

  • Age:
      - Infants have immature immune defenses.
      - Older adults experience a decline in immune functionality.

  • Sex:
      - May influence susceptibility to infection.

  • Nutritional Status:
      - Poor nutrition can compromise immune defense and wound healing.

  • Stress:
      - Prolonged stress can lead to decreased resistance against infections.

  • Disease Processes:
      - Conditions affecting the immune system (e.g., leukemia, HIV/AIDS) elevate infection risks.

INFECTION ASSESSMENT

  • Conduct a comprehensive evaluation to identify risk factors for infection:
      - Physical Assessment:
        - Identify areas of infection or vulnerability.
      - Defense Mechanisms:
        - Assess the normal defenses against infection.
      - Drug Assessment:
        - Examine medications that may compromise immunity, such as cytotoxic drugs and steroids.
      - Travel History:
        - Evaluate any recent travel that may influence infection exposure.
      - Laboratory Data:
        - Review lab results to screen for infections.

INFECTION PLANNING

  • Align patient care with evidence-based practices (EBP).

  • Control the environment to prevent infection transmission.

  • Cultural Considerations:
      - Factor in culture when designing patient-centered interventions.

  • Establish Priorities:
      - Identify key interventions based on individual patient needs.

HEALTH PROMOTION

  • Nutrition:
      - Educate about maintaining a proper diet for immune function.

  • Hygiene:
      - Instruct on skin cleansing techniques and methods to prevent microorganism spread.

  • Immunization:
      - Promote vaccination to reduce risk of infections.

  • Overall Health:
      - Encourage adequate rest and regular exercise.

MEDICAL ASEPSIS

  • Definition:
      - Asepsis is the absence of pathogenic microorganisms.

  • Control Measures:
      - Hand hygiene, use of personal protective equipment (PPE), and routine cleaning.

  • Sterilization:
      - Eliminates all microbial life, including spores, ensuring safe medical environments.

BREAKING THE CHAIN OF INFECTION

  • Cleanliness and Sterilization:
      - Objects should be cleaned/sterilized as necessary.

  • Body Defenses:
      - Improve the body's natural defenses against infections.

  • Eliminating Reservoirs:
      - Examples include managing drainage and proper food storage.

  • Cough Etiquette:
      - Cover mouth/nose when coughing/sneezing.

  • PPE Usage:
      - Wear appropriate PPE as necessary.

  • Hand Hygiene:
      - Strict adherence to hand hygiene protocols.

  • Linens:
      - Do not place soiled linens on the floor.

ISOLATION PRECAUTIONS

  • Standard Precautions:
      - Apply to all patients for primary infection prevention.

  • Types of Precautions:
      - Contact Precautions
      - Droplet Precautions
      - Airborne Precautions
      - Protective Environment Guidelines

CARING FOR PATIENTS ON ISOLATION

  • Considerations:
      - Be aware of psychological effects of isolation.
      - Provide comfort measures.
      - Maintain visibility (e.g., open curtains).
      - Clearly explain the rationale for isolation.
      - Isolation signage should be displayed on the door.

PERSONAL PROTECTIVE EQUIPMENT (PPE)

  • Types of PPE:
      - Gowns
      - Surgical masks
      - N95 respirators
      - Protective eyewear
      - Gloves

SURGICAL ASEPSIS

  • Definition:
      - Surgical asepsis involves maintaining sterile techniques

  • Applications:
      - Used in high-risk procedures, such as IV insertion, urinary catheterization, tracheal suctioning, wound care, etc.

EXPOSURE ISSUES

  • Healthcare Provider Risks:
      - High risk for needlestick injuries.

  • Safety Protocols:
      - Activate safety devices on needles immediately following use; dispose in a sharps container.

  • Infections:
      - Be aware of HBV and HCV risks from contaminated needles.

  • Reporting:
      - Immediately report any needlestick injury involving contamination.

TABLES / BOXES FOR REVIEW

  • Tables and Boxes included:
      - Table 28.1: Infection and Common Causative Organisms
      - Box 28.1: Modes of Transmission
      - Box 28.1: Course of Infection by Stage
      - Table 28.3: Host Characteristics Influencing Susceptibility to and Severity of Disease
      - Table 28.4: Laboratory Tests to Screen for Infection
      - Box 28.9: Infection Prevention and Control: Protecting the Susceptible Host
      - Box 28.10: Infection Prevention and Control to Reduce Reservoirs of Infection
      - Table 28.6: CDC Isolation Guidelines