Infection
Definitions
Pathogen (agent): Microorganism capable of producing disease.
Communicable: Infection transmitted from person to person.
Pathogenicity: Ability to cause disease.
Virulence: Degree of communicability.
Additional Definitions
Normal Flora: Characteristic bacteria of a specific body location that often compete with other microorganisms to prevent infections.
Surveillance: The tracking and reporting of infections.
Transmission of Infectious Agents
Key Components:
Reservoir: The natural habitat of the infectious agent.
Susceptible Host: An individual who is at risk for infection.
Mode of Transmission: Mechanism through which an infectious agent is transferred.
Immunity
Definition: Resistance to infection generally associated with the presence of antibodies or cells that act on specific microorganisms.
Types of Immunity
Passive Immunity:
Duration: Short-lived.
Acquisition: Transplacental transfer from mother or artificial injection of antibodies.
Active Immunity:
Duration: Long-lasting.
Acquisition: Natural (by actual infection) or artificial (by vaccination).
Routes of Transmission
Main Routes:
Respiratory Tract
Gastrointestinal Tract
Genitourinary Tract
Skin/Mucous Membranes
Bloodstream
Methods of Transmission
Types of Transmission:
Contact: Can be either direct or indirect.
Droplet: Transmission of infectious agents through larger respiratory droplets.
Airborne: Infectious agents spread via smaller particles that remain suspended in the air.
Vector-Borne: Transmission through insects or animals.
Environmental: Transmission through contaminated food or water.
Portal of Exit: Pathway by which pathogens leave the host.
Physiologic Defenses Against Infection
Components:
Body Tissues: The physical barriers to infection.
Phagocytosis: The process by which immune cells engulf and digest pathogens.
Inflammation: The body's immediate response to injury or infection.
Immune Systems:
Antibody-Mediated Immunity: Involves antibodies produced by B cells
Cell-Mediated Immunity: Involves T cells which attack infected cells directly.
Health Promotion and Maintenance
Health Care–Associated Infection (HAI): Infection acquired in an inpatient setting not present at admission.
Types of Infection:
Endogenous Infection: Originating from patient flora.
Exogenous Infection: From external sources, often from tubes, implants, or healthcare workers’ hands.
Also termed: Nosocomial Infection.
Methods of Infection Control and Prevention
Key Strategies:
Hand Hygiene: Essential practice to reduce the risk of infection.
Disinfection/Sterilization: Processes to eliminate or reduce microbial load.
Standard Precautions: Basic infection prevention practices applied to all patients.
Transmission-Based Precautions:
Airborne Precautions
Droplet Precautions
Contact Precautions
Staff and Patient Placement: Proper cohorting and physical separation of patients when necessary.
Infectious Disease Precautions
Practices for Everyone:
Hand Hygiene: Clean hands before entering or leaving the room.
Practices for Providers and Staff:
Gloves: Must be worn before room entry and discarded before exit.
Gown: Should be worn before entry and discarded appropriately.
Use of Equipment: Should be dedicated or properly sterilized between uses.
Multidrug-Resistant Organisms (MDROs)
Definition: Microorganisms that have developed resistance to multiple antibiotics.
Common MDROs:
Methicillin-resistant Staphylococcus aureus (MRSA)
Vancomycin-resistant Enterococcus (VRE)
Carbapenem-resistant Enterobacteriaceae (CRE)
Methicillin-Resistant Staphylococcus Aureus (MRSA)
Description: A strain of Staphylococcus aureus resistant to methicillin and other penicillin-based drugs.
Treatment: Often susceptible to vancomycin, linezolid, and ceftaroline fosamil.
Spread by:
Indwelling urinary catheters
Vascular access devices
Endotracheal tubes
Community-Associated MRSA (CA-MRSA)
Characteristics: Causes infections in healthy, non-hospitalized individuals.
Health Education: Important measures include:
Frequent hand hygiene, including hand sanitizers.
Avoiding close contact with individuals who have infectious wounds.
Steering clear of large crowds and contaminated surfaces.
Maintaining overall good hygiene practices.
Other Multidrug-Resistant Organisms
Vancomycin-resistant Enterococcus (VRE)
Carbapenem-resistant Enterobacteriaceae (CRE)
Problems from Inadequate Antimicrobial Therapy
Consequences:
Noncompliance/nonadherence to treatment plans.
Legal interventions may compel patients to complete treatment (e.g., for tuberculosis).
Septicemia or bloodstream infections (BSI).
Septic shock can occur as a result of untreated severe infections.
Infectious Complications
Role of Various Factors:
Exposure to exogenous organisms, including MDROs.
Poor Infection Control Practices.
Frequent use of Invasive Devices.
Altered Immunity in certain populations increases infection risk.
Patient-Centered Collaborative Care
Assessment Areas:
History-taking: Gathering detailed patient information.
Physical Assessment: Evaluating clinical manifestations relevant to infection.
Psychosocial Assessment: Understanding the patient's overall wellbeing and impact of infection.
Laboratory Assessment
Key Tests:
Culture and Antibiotic Sensitivity Testing: Identify pathogens and guide treatment.
White Blood Cell Count (WBC): Measure of body's immune response.
Erythrocyte Sedimentation Rate (ESR): Indicator of inflammation.
Serologic Testing: Assess immune responses and identify infections.
White Blood Cells (WBCs)
Functions: Stimulate the inflammatory response and protect against infections.
Types of WBCs:
Neutrophils
Lymphocytes
Monocytes
Eosinophils
Basophils
Leukopenia: WBC count less than 4,000
Leukocytosis: WBC count greater than 10,000
Left Shift in WBCs
Definition: A clinical term indicating an elevated band count due to increased immature neutrophils, often associated with acute infections.
Causes: Commonly due to inflammation but can also indicate marrow disorders or severe injury.
Neutropenic Precautions
Definition: Neutropenia refers to a neutrophil count of less than 2,000.
Absolute Neutrophil Count (ANC): Used to evaluate the risk for infection.
Precautions: ANC less than 1,000 requires additional measures:
Restrictions on visitors and avoidance of sick people.
Prohibition against live plants and fresh foods.
Avoiding intramuscular injections or rectal temperatures.
Planning and Implementation
Managing Hyperthermia:
Eliminate the cause of the fever.
Destroy causative microorganisms.
Utilize drug therapy as needed.
Implement external cooling techniques.
Ensure fluid administration is adequate.
Community-Based Care
Components:
Home care management strategies for patients post-infection.
Self-management education for ongoing health maintenance.
Identification and utilization of healthcare resources.
Emerging Infections and Global Bioterrorism
Focus Areas:
Identifying emerging infectious diseases.
Addressing the rise of multidrug-resistant organisms (MDROs).
Awareness and management of pandemic infections.
Risks associated with contaminated food.
Specific mention of Clostridium difficile (C. difficile) and COVID-19.
Case Study Example
Scenario: A 27-year-old patient admitted for cellulitis due to MRSA.
Considerations for Isolation:
Preparation of an isolation room upon patient arrival.
Implementation of special precautions specific to MRSA infection, including:
Keeping the door closed.
Wearing gloves and gowns when entering.
Use of dedicated equipment for the patient.
Medication Management
Likely Treatment for MRSA: Providers often order Vancomycin (Vancocin) to combat MRSA infections.
Patient Education on Infection Transmission
Best Response for MRSA: Educate patients that MRSA spreads primarily through direct contact in both hospital and community settings.
Audience Response System Questions
Examples of Questions:
Appropriate use of alcohol-based hand rubs.
Identifying patients at greatest risk of infection.
Most frequently occurring health care acquired infections (HCAIs).
Common