infection

Primary Defenses

Physical and chemical barriers that protect the body from pathogens.

Skin

Acts as a barrier against pathogens.

Mucous Membranes

Trap pathogens in the respiratory, gastrointestinal, and genitourinary tracts.

Acidic pH

Prevents bacterial growth on skin and within the stomach.

Cilia

Tiny hairs in the respiratory tract that push out inhaled particles.

Immunoglobulins

Also known as antibodies; produced by B lymphocytes to neutralize pathogens.

Neutrophils

First responders to infection.

Lymphocytes

Include B and T cells that produce antibodies.

White Blood Cells (WBCs)

Cells that fight against infection.

Monocytes

Become macrophages and engulf pathogens.

Eosinophils

Fight parasites and are involved in allergic reactions.

Basophils

Release histamine during allergic responses.

Macrophages

Phagocytes that engulf and digest pathogens.

Phagocytosis

Process by which macrophages ingest pathogens.

Inflammatory Response three

The body's reaction to injury, infection, or trauma.

three stages of inflammatory response

Vascular Response

Involves vasodilation, leading to increased blood flow and redness.

Inflammatory Exudate

Plasma that leaks into tissues causing swelling and pain.

Phagocytosis & Purulent Exudate

WBCs engulf pathogens; possible pus formation.

Natural Immunity

Species-specific and inherited protection from pathogens.

Active Immunity

Develops from infection or vaccination.

Passive Immunity

Immunity passed from mother to baby or through immunoglobulin injections.

Risk Factors for Infection

Conditions that make individuals more susceptible to infections.

• 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).

Localized Infection

Infection affecting one area of the body.

• Symptoms: Pain, redness, swelling, warmth.

Systemic Infection

Infection that spreads throughout the body via the bloodstream.

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

Gram Stain

Lab test that identifies bacteria based on cell wall characteristics.

1. Gram-positive → Stains purple.

2. Gram-negative → Stains pink.

Culture & Sensitivity (C&S)

Test to identify bacteria and determine antibiotic effectiveness.

Serum Antibody Test

Detects past exposure to antigens.(does not confirm current infection).

CBC with Differential

Measures types of WBCs to assess infection.

ESR (Erythrocyte Sedimentation Rate)

Screens for inflammation.

Other Tests:

TB skin test, MRI, CT scan, X-ray

Medical Asepsis

Reduces 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

Eliminates all microorganisms and spores ; used in surgical procedures.

Used for:

• Surgical procedures.

• Catheter insertions.

• Central line placement.

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sterile technique

Respiratory Infections

Higher mortality rate in intubated patients; prevention includes oral hygiene.

• Prevention of respiratory infection

• Oral hygiene.

• Coughing & deep breathing.

• Incentive spirometry.

• Elevate head of bed.

Urinary Tract Infections (UTIs)

Most common healthcare-associated infection.

• Prevention of uti

• • Sterile catheter insertion.

  • Secure tubing & maintain a closed system.

  • Remove catheters ASAP.

Signs to monitor in surgical wounds.

Drainage, odor, color, pain

9. Antibiotic-Resistant Infections

Infections caused by bacteria that no longer respond to standard antibiotics, making treatment more difficult.

MRSA

Methicillin-resistant Staphylococcus Aureus, difficult to treat.

VRE

Vancomycin-resistant Enterococcus; requires strict precautions.

• Risk factors: Catheters, central lines, immunosuppression.

C. difficile (C. diff)

Bacterium causing severe diarrhea, not killed by hand sanitizer.

• Treatment: Metronidazole, Vancomycin, Fecal Transplant.

Antigen

Substance that triggers an immune response.

Antibody

Protein that binds to an antigen to neutralize it.

Asepsis

The absence of pathogenic microorganisms.

Colonization

Presence of microorganisms without causing disease.

Bacteremia

Presence of bacteria in the bloodstream.

Sepsis

Life-threatening condition from a severe infection.

Bactericidal

An antibiotic that kills bacteria.

Bacteriostatic

An antibiotic that inhibits bacterial growth.

Antibiotic Stewardship

Strategy to reduce antibiotic overuse.

Catheter-Associated Urinary Tract Infection (CAUTI)

UTI caused by prolonged catheter use.