infection

A. Primary Defenses (Physical & Chemical Barriers)

1. Skin & Mucous Membranes

   • Skin acts as a barrier against pathogens.

   • Mucous membranes in the respiratory, gastrointestinal, and genitourinary tracts trap pathogens.

   • Acidic pH of skin & stomach acid prevents bacterial growth.

   • Cilia in the respiratory tract push out inhaled particles.

2. Immunoglobulins (Antibodies)

   • Produced by B lymphocytes when the body detects a foreign antigen.

   • Act as antibodies to neutralize and destroy pathogens.

3. White Blood Cells (Leukocytes)

   • Fight and protect against infection.

   • Types of WBCs:

     • Neutrophils – First responders to infection.

     • Lymphocytes – Include B and T cells that produce antibodies.

     • Monocytes – Become macrophages and engulf pathogens.

     • Eosinophils – Fight parasites and are involved in allergic reactions.

     • Basophils – Release histamine during allergic responses.

4. Macrophages (Phagocytes)

   • Engulf and ingest pathogens (phagocytosis).

   • Help remove cellular debris and trigger the immune response.

2. Inflammatory Response

The inflammatory response is the body's reaction to injury, infection, or trauma.

Three Stages of Inflammation:

1. Vascular Response:

   • Vasodilation increases blood flow → Causes redness and heat.

2. Inflammatory Exudate:

   • Plasma leaks into tissues → Causes swelling and pain.

3. Phagocytosis & Purulent Exudate:

   • WBCs engulf pathogens → Possible pus formation.

3. Immune System & Immunity

The immune system protects the body by detecting and eliminating pathogens.

Types of Immunity

1. Natural Immunity: Species-specific, inherited protection.

2. Acquired Immunity:

   • Active Immunity: Develops from infection or vaccination.

   • Passive Immunity: Passed from mother to baby or immunoglobulin injections.

4. Risk Factors for Infection

Certain conditions make individuals more vulnerable to infection.

• Elderly (weakened immune response).

• Immunocompromised individuals (HIV, cancer, chronic illness).

• Chronic diseases (diabetes, COPD).

• Dysphagia (trouble swallowing → aspiration pneumonia risk).

• Hospital & long-term care settings (higher exposure to pathogens).

• Medical devices (catheters, IVs, feeding tubes, ventilators).

5. Localized vs. Systemic Infection

Localized Infection

• It affects one area of the body.

• Symptoms: Pain, redness, swelling, warmth.

Systemic Infection

• Spreads throughout the body via bloodstream.

• Symptoms: Fever, fatigue, increased WBC count, chills, body aches.

6. Diagnostic Procedures

1. Gram Stain:

   • Identifies bacteria under a microscope.

   • Gram-positive → Stains purple.

   • Gram-negative → Stains pink.

2. Culture & Sensitivity (C&S):

   • Grows bacteria to identify it and determine antibiotic effectiveness.

3. Serum Antibody Test:

   • Detects past exposure to an antigen (does not confirm current infection).

4. CBC with Differential:

   • Measures different types of WBCs to assess infection.

5. ESR (Erythrocyte Sedimentation Rate):

   • Screens for inflammation.

6. Other Tests: TB skin test, MRI, CT scan, X-ray.

7. Asepsis

Medical Asepsis (Clean Technique)

• Reduces the number of pathogens to prevent transmission.

• Includes:

  • Hand hygiene – Most effective way to prevent infection.

  • PPE (gloves, gowns, masks, goggles).

  • Cleaning surfaces with disinfectants.

  • Short nails, no artificial nails, minimal jewelry.

Surgical Asepsis (Sterile Technique)

• Eliminates all microorganisms & spores (used in surgery).

• Used for:

  • Surgical procedures.

  • Catheter insertions.

  • Central line placement.

8. Specific Infection Types & Nursing Care

Respiratory Infections

• Higher mortality rate in intubated patients.

• Prevention:

  • Oral hygiene.

  • Coughing & deep breathing.

  • Incentive spirometry.

  • Elevate head of bed.

Urinary Tract Infections (UTIs)

• Most common healthcare-associated infection (CAUTIs).

• Prevention:

  • Sterile catheter insertion.

  • Secure tubing & maintain a closed system.

  • Remove catheters ASAP.

Surgical Wounds

• Monitor for:

  • Drainage, odor, color, pain.

  • Skin condition around the wound.

  • Dressing changes as ordered.

9. Antibiotic-Resistant Infections

• MRSA (Methicillin-Resistant Staphylococcus Aureus)

  • Highly contagious, difficult to treat.

  • Requires Vancomycin & strict isolation precautions.

• VRE (Vancomycin-Resistant Enterococcus)

  • Pathogenic strain of Enterococcus.

  • Risk factors: Catheters, central lines, immunosuppression.

• C. difficile (C. diff)

  • Causes severe diarrhea.

  • Not killed by hand sanitizer – Requires soap & water.

  • Treatment: Metronidazole, Vancomycin, Fecal Transplant.

10. Nursing Care Considerations for Antibiotics

• Obtain cultures before starting antibiotics.

• Monitor for allergic reactions (anaphylaxis).

• Check peak & trough levels for strong antibiotics.

• Encourage probiotics to maintain gut flora.

• Watch for superinfections (yeast infections, oral thrush

Glossary of Key Terms

General Infection & Immunology

• Antigen: A substance (protein or carbohydrate) that triggers an immune response, leading to antibody production.

• Antibody: A protein produced by the immune system that binds to an antigen to neutralize or eliminate it.

• Asepsis: The absence of pathogenic microorganisms.

• Colonization: The presence of microorganisms in or on a host without causing disease.

• Culture and Sensitivity (C&S): A lab test to identify infection-causing microorganisms and determine effective antibiotics.

• Gram Stain: A lab test that classifies bacteria as gram-positive (purple) or gram-negative (pink) based on cell wall structure.

• Inflammation: A localized reaction to injury or infection, causing redness, swelling, heat, and pain.

• Leukocytes: White blood cells that help fight infection.

Types of Infection & Complications

• Bacteremia: Presence of bacteria in the bloodstream.

• Sepsis: A life-threatening condition caused by a severe infection that triggers a systemic inflammatory response.

• Localized Infection: Infection confined to one area of the body.

• Systemic Infection: Infection that spreads throughout the body, often via the bloodstream.

Antibiotics & Resistance

• Bactericidal: An antibiotic that kills bacteria directly.

• Bacteriostatic: An antibiotic that inhibits bacterial growth.

• Antibiotic Stewardship: A strategy to reduce antibiotic overuse and prevent antibiotic resistance.

Aseptic Techniques & Infection Prevention

• Medical Asepsis: Reduces the number and spread of pathogens (e.g., hand hygiene, PPE).

• Surgical Asepsis: Eliminates all microorganisms and spores (e.g., sterile procedures).

Common Healthcare-Associated Infections

• Catheter-Associated Urinary Tract Infection (CAUTI): A UTI caused by prolonged catheter use.

• Methicillin-resistant Staphylococcus Aureus (MRSA): A drug-resistant bacterial infection requiring strict infection control measures.

• Vancomycin-Resistant Enterococci (VRE): A strain of bacteria resistant to vancomycin that requires contact precautions.

• C. difficile (Clostridioides difficile): A bacterium that causes severe diarrhea and colitis, often after antibiotic use.