INFECTION_CONTROL_NOTES_1ST_SEM

Infection Control Overview

Introduction

  • Every person is susceptible to infections caused by pathogens.

Infection Definition

  • Infection: Invasion of the host by a pathogen.

    • Characterized by 5 signs:

      • Pain

      • Swelling

      • Redness

      • Heat

      • Impaired function of the body part

Nature of Infections

Micro-organisms

  • Types include:

    • Bacteria

    • Fungi

    • Viruses

    • Protozoa

    • Worms

  • Most micro-organisms are harmless (non-pathogenic); pathogenic organisms cause infections.

Stages of Infection

  • 1. Incubation Period: The pathogen has entered the host and is replicating silently.

  • 2. Prodromal Period: Mild, nonspecific symptoms appear (e.g., itchy, running nose).

  • 3. Illness/Clinical Phase: Typical signs and symptoms of disease manifest.

  • 4. Decline: Symptoms begin to subside.

  • 5. Convalescence/Recovery Phase: Symptoms disappear, tissues heal, and the body regains strength.

Routes of Entry For Infection

  • Natural Orifices: Mouth, nose, ear, eye, urethra, vagina, rectum.

  • Artificial Orifices: Tracheostomy, ileostomy, colostomy.

  • Mucous Membranes: Line most natural and artificial orifices.

  • Skin Breaks: Accidental damage or deliberate inoculation/incision.

Chain of Infection

Components

  1. Infectious Agent: Bacteria, virus, fungi, or infectious protozoa.

  2. Reservoirs: People, wounds, mucosa, equipment, animals, etc.

  3. Susceptible Host: Individuals with non-immunity or immune deficiency.

  4. Portal of Exit: Exit routes include coughing, sneezing, bleeding, feces.

  5. Modes of Transmission: Contact (hands, sharp injuries), airborne, vector.

Factors Increasing Susceptibility to Infection

  • External Factors: Exposure to infectious agents, pollution, immune suppressors.

  • Host Factors: Compromised barriers (skin, mucosa), allergic inflammation, genetic deficiencies.

  • Medical Conditions: Diabetes, cancer, organ transplants weaken the immune response.

  • Other Factors: Malnutrition, alcoholism, cellular immune dysfunction.

Types of Infections

Categories

  • Primary Infection: Initial infection in a healthy host.

  • Secondary Infection: New infection in a host with lowered resistance.

  • Local Infection: Limited to a specific area or organ.

  • Systemic Infection: Spreads throughout the body, resulting in sepsis.

  • Acute Infection: Sudden onset and short duration.

  • Chronic Infection: Develops slowly, lasting for months or years.

  • Iatrogenic Infection: Results from medical procedures.

  • Nosocomial Infection: Acquired in healthcare settings.

Risk Groups for Infection

  • Staff: Daily exposure to infectious blood and fluids.

  • Clients: Risk of infections post-procedure, often due to poor hygiene and aseptic techniques.

  • Community: Risks from improper disposal of medical waste.

Body Defense Against Infection

Defense Mechanisms

  1. Physical and Chemical Barriers:

    • Skin: Protective outer barrier, creates an inhospitable environment for pathogens.

    • Mucous Membranes: Traps pathogens in the respiratory, digestive, and urogenital tracts.

    • Cilia: Moves mucus and pathogens out of the lungs.

    • Enzymes: Break down pathogens in saliva, tears, and stomach acid.

  2. Innate Immune System:

    • Phagocytes: Consume pathogens.

    • NK Cells: Destroy infected or abnormal cells.

    • Inflammation: Increases blood flow, causing redness and swelling.

    • Complement System: Destroys pathogens by puncturing their membranes.

  3. Adaptive Immune System:

    • T-Cells: Recognize and kill infected cells.

    • B-Cells: Produce antibodies targeting specific pathogens.

    • Memory Cells: Provide a faster immune response upon re-infection.

  4. Fever: Rise in temperature inhibits pathogen growth and supports immune cell efficacy.

  5. Microbiome: Beneficial bacteria compete with pathogens, limiting their growth.

Nosocomial Infections

Definition

  • Infections acquired during healthcare delivery or while under medical supervision.

Risk Factors

  • Invasive procedures, contaminated equipment, lack of aseptic techniques.

Infection Control Measures

Asepsis

  • Asepsis: State free from disease-causing contaminants.

    • Medical Asepsis: Prevents growth of pathogens (clean technique).

    • Surgical Asepsis: Total destruction of all microorganisms (sterile technique).

Personal Protective Equipment (PPE)

  • Essential for preventing the transmission of pathogens. Includes gowns, masks, and gloves.

Standard Safety Precautions

  • Hand hygiene, proper use of PPE, and safe disposal of sharps to prevent exposure to infections.