Lecture Notes: Concept of Infection

Key Terms

• Infection: Growth of microorganisms in body tissues where they are not usually found.
• Disease: Detectable alteration in normal tissue function.
• Virulence: A microorganism's ability to cause disease.
• Pathogenicity: The ability to produce disease.
  • True pathogens: Affect healthy individuals.
  • Opportunistic pathogens: Cause disease in susceptible individuals (e.g., compromised immune systems).

Types of Infection

• Colonization: Microorganisms become resident flora, e.g., Staphylococcus.
• Local infection: Limited to a specific body part.
• Systemic infection: Spreads throughout the body, possibly leading to bacteremia or septicemia.
• Acute infections: Sudden onset, short course (e.g., cold, strep throat).
• Chronic infections: Slow development, long-lasting (e.g., COPD).
• Nosocomial infections: Acquired in hospital settings.
  • Endogenous: Originates from the patient.
  • Exogenous: Originates from the hospital environment or personnel.

Healthcare-Associated Infections (HAIs)

• Leading complication of hospital care.
• Common types: Central IV-associated bloodstream infections, catheter-associated UTI, ventilator-associated pneumonia.
• Factors promoting HAIs: Inadequate hand hygiene, improper techniques.
• Prevention: Proper hand hygiene is critical.

Body’s Response to Infection

Localized Infection Signs

• Heat, Pain, Edema, Redness.

Systemic Infection Signs

• Fever, Increased pulse/respiratory rate, Malaise, Anorexia, Lymphadenopathy.

Infection Process Stages

1. Incubation: Microorganism grows without symptoms.
2. Prodromal: Most infectious stage with vague symptoms.
3. Illness: Specific signs and symptoms.
4. Convalescent: Recovery phase.

Chain of Infection

• Infectious agent: Microorganism like bacteria or viruses.
• Reservoir: Where the microorganism lives (e.g., respiratory tract).
• Portal of exit: How it leaves the host (e.g., sneezing).
• Mode of transmission: How it spreads (e.g., airborne, droplet).
• Portal of entry: Entry point in the new host (e.g., inhalation).
• Susceptible host: Individuals at risk (e.g., immunocompromised, infants).

Breaking the Chain of Infection

• Hygiene and Infection Control: Clean/sterilize items, educate patients.
• Hand Hygiene: Essential for preventing the spread.

Asepsis and Hygiene

• Medical Asepsis: Limits microorganism growth.
• Surgical Asepsis: Keeps environment free of all microorganisms.
• Aseptic Techniques: Ensure sterile environment during procedures.

Defenses Against Infection

• Nonspecific defenses: Skin, mucous membranes.
• Specific defenses: Antibody and cell-mediated responses.

CDC Guidelines and Precautions

• Standard Precautions: For all patients (includes hand hygiene, PPE use).
• Transmission-Based Precautions: Added precautions for specific infections (Airborne, Droplet, Contact).
• PPE Usage: Proper donning and doffing procedures.

Example Scenarios

• Recognizing Infections: Identifying acute vs. chronic infections.
• Lab Tests: WBC count to indicate infection.
• PPE in Practice: Appropriate protective measures during patient care.

Conclusion

• Importance of understanding infection processes, prevention strategies, and proper hygiene to manage and reduce the risk of infections within healthcare settings.