Infection

Care of the Patient with Infection/Altered Immunity

Overview of Infection

  • Infection: An interaction between a host and a pathogenic organism.

    • Colonization: Microorganisms present without interference or interaction from the host.

    • Colony count: 100,000/mL indicates significant colonization.

    • Infectious disease: A disease caused by the growth of pathogenic microbes.

    • Nosocomial: Infections originating in a hospital environment.

    • Types of Infections:

    • Exogenous: Causative organism acquired from other individuals.

    • Endogenous: Causative organism is harbored within the individual’s body.

    • Iatrogenic: Resulting from a treatment or diagnostic procedure.

Chain of Infection

  • Components of the Chain:

    • Causative Organism: The pathogen responsible for the disease.

    • Reservoir of Organisms: Environment where the pathogen can live and multiply (human hosts, animals, surfaces).

    • Portal of Exit from Reservoir: Pathway by which the pathogen leaves the reservoir (e.g., respiratory tract, open wounds).

    • Mode of Transmission to Host: How the pathogen spreads (direct contact, airborne).

    • Susceptible Host: Individual who can contract the infection due to lack of immunity.

    • Mode of Entry to Host: How the pathogen enters the new host (e.g., mucous membranes, skin breaks).

Overview of Immunity

  • Natural Immunity:

    • Physical/Chemical Barriers:

    • Physical: Skin and cilia that trap and expel particles.

    • Chemical: Mucus, gastric secretions, and normal flora.

    • Inflammatory Response:

    • Triggered by the release of chemicals that activate phagocytes and mast cells; critical in initial defense.

    • Immune Response:

    • Phagocytes: Engulf and digest foreign particles.

    • B lymphocytes: Produce antibodies targeting specific pathogens.

    • T lymphocytes: Differentiate into killer T cells that destroy damaged or infected cells.

  • Acquired Immunity:

    • Active: Developed by one’s own body, often following exposure to a pathogen or vaccination.

    • Passive: Acquired through external sources (e.g., maternal antibodies), providing immediate but temporary immunity.

Immunodeficiency

  • Primary Immunodeficiency:

    • Genetic in origin; affects the immune system from birth.

    • Examples include Immunoglobulin A deficiency and DiGeorge Syndrome.

  • Secondary Immunodeficiency:

    • Results from external factors impairing immune function.

    • Common examples: HIV infection and the effects of immunosuppressive therapy.

Inflammation and Infection

  • Inflammation:

    • The body’s response to harmful stimuli, characterized by warmth, redness, swelling, pain, and loss of function.

    • Inflammation does not always indicate infection.

    • Lab Values:

    • Often include elevated Leukocytes (WBC), e.g., neutrophils, macrophages, monocytes, eosinophils, basophils.

    • Elevated Erythrocyte Sedimentation Rate (ESR) is common in inflammatory conditions.

Infection Manifestations

  • Signs of Inflammation: Often visible in localized infections (e.g. pus, redness).

    • Possible systemic signs include:

    • Fever

    • Chills

    • Malaise

    • Tachycardia

    • Lymphadenopathy

    • Pharyngitis

    • GI disturbances (N/V/D)

  • Lab Values for Diagnosis:

    • Similar to inflammation; includes blood/wound/tissue cultures and imaging (X-ray, CT scan, MRI, Ultrasonography).

Impaired Immunity Manifestations

  • Common Symptoms:

    • Frequent infections

    • Digestive problems

    • Blood disorders

    • Fatigue

    • Delayed wound healing

    • Presence of autoimmune diseases

  • Lab Values:

    • Low leukocyte counts (WBC).

    • Impaired functioning of lymphocytes, specifically B Cells, T cells.

    • Shift left in neutrophil counts indicates a higher concentration of immature neutrophils (bands) compared to mature neutrophils.

Healthcare-Associated Infections (HAI): 2025 Update

  • Statistics:

    • Patients admitted to hospitals have a 1 in 31 chance of contracting an HAI.

    • Prevalence: 687,000 people contract HAIs annually in the U.S.

    • Cost Impact:

    • Patients experience an increased hospital stay of 17.6 days due to HAIs.

    • Total cost impact: $35 billion/year.

    • The average additional cost per admission: $1,100.

    • Mortality: 72,000 deaths yearly attributed to HAIs, with specific diseases represented in casualty statistics (e.g., diabetes, gastrointestinal diseases, heart failure, cancers).

Types of Healthcare-Associated Infections:

  • Types:

    • Central Line-associated Bloodstream Infection (CLABSI)

    • Catheter-associated Urinary Tract Infection (CAUTI)

    • Surgical Site Infection (SSI)

    • Ventilator-associated Pneumonia (VAP)

Antibiotic Resistant Organisms

Methicillin-Resistant Staphylococcus Aureus (MRSA)

  • Characteristics:

    • Strain of Staphylococcus aureus that is resistant to common antibiotics.

    • Locations: skin, mucous membranes, respiratory and GI tracts.

  • Signs/Symptoms: Include bumps, boils, redness, tenderness, swelling, feeling warm, fever, and drainage.

  • At-Risk Populations:

    • Young children

    • Elderly

    • Individuals with HIV/AIDS

    • Those living in crowded conditions or undergoing invasive procedures.

  • Diagnosis: Tissue or nasal sample culture.

  • Complications: Can lead to pneumonia, bloodstream infections (sepsis), surgical site infections, and possibly death.

  • Patient Education Points:

    • Wound care: Cover wounds, do not pop sores, and practice good hygiene.

    • Complete the entire course of antibiotics to prevent resistance!

  • Treatment Options:

    • Incision and drainage of abscesses as needed.

    • Antibiotic therapies: Vancomycin, Trimethoprim-sulfamethoxazole (Bactrim), Linezolid, topical antiseptics such as CHG.

Vancomycin Intermediate-resistant Staphylococcus Aureus (VISA) and Vancomycin Resistant Staphylococcus Aureus (VRSA)

  • Risk Factors:

    • Presence of underlying health conditions (example: kidney disease, dialysis).

    • History of MRSA infection or previous treatment with vancomycin.

  • Manifestations: Include skin infections/abscesses, pneumonia, and infections affecting heart valves, bones, or blood.

  • Diagnosis: Culture of the site of infection.

  • Treatment Options:

    • Common antibiotics include Linezolid (Zyvox) and Daptomycin (Cubicin).

  • Management: Includes prevention strategies (hand hygiene, cleaning of equipment), contact isolation for as long as entering can present a risk.

Vancomycin Resistant Enterococci (VRE)

  • Characteristics: Enterococci normally found in the intestines and genital tract that are resistant to vancomycin.

  • Risk Factors:

    • Having a compromised immune system.

    • Recent abdominal or chest surgery.

    • Presence of central venous catheters or urinary catheters.

  • Manifestations: Diverse range of infections such as urinary tract infections (UTIs), bacteremia, endocarditis, meningitis.

  • Diagnosis: Culture of the infected area.

  • Treatment Options: Linezolid (Zyvox), Daptomycin (Cubicin), Tigecycline (Tygacil).

  • Management: Implement principles of prevention, maintain hand hygiene, and sanitize environments/medical equipment; contact isolation until determined safe via screening negative cultures.

Acinetobactor Baumannii

  • Characteristics: A group of bacteria found in soil and aquatic environments.

  • Risk Factors:

    • Weakened immune systems, chronic lung disease, diabetes, extended hospital stays, open wounds, and being on a ventilator.

  • Manifestations: Range from pneumonia to severe bloodstream infections and wound infections.

  • Diagnosis: Growth from lab specimens such as sputum, blood, or cerebrospinal fluid (CSF).

  • Treatment Options: Antibiotic therapy, particularly using carbapenem antibiotics (e.g., doripenem).

  • Management: Contact isolation until recovery and resolution of symptoms; reinforce environmental hygiene practices.

Carbapenem-Resistant Enterobacteriaceae (CRE)

  • Characteristics: A family of bacteria typically residing in human intestines that are resistant to carbapenem antibiotics.

  • Risk Factors:

    • Seriously ill patients and those who have received long-term antibiotics.

    • Presence of catheters or other access devices.

  • Manifestations: Can cause pneumonia, bloodstream infections, urinary tract infections, as well as wound infections and meningitis.

  • Diagnosis: Culturing for infection with sensitivity tests.

  • Treatment: Notoriously resistant to antibiotic treatment; requires stringent management and care protocols.

  • Management: Continual contact precautions, rigorous hand hygiene, proper environmental cleaning, and routine CHG baths with a very high mortality rate associated (40-50%).

Clostridium Difficile (C. Diff)

  • Characteristics: Associated with antibiotic use and found predominantly in hospitalized patients.

  • Risk Factors:

    • Advanced age, prolonged hospitalization, and previous exposure to antibiotics.

  • Manifestations:

    • Diarrhea (both mucus and blood possible), abdominal cramping, anorexia, fever, leukocytosis, and possible dehydration.

  • Diagnosis: Based on diarrhea presence, positive stool sample tests, colonoscopic findings showing pseudomembranous colitis, and a relevant treatment history.

  • Treatment Options:

    • First-line: Vancomycin (Vancocin) orally or Fidaxomicin (Dificid).

    • Second-line: IV or PO Metronidazole (Flagyl).

    • Fecal transplants may be considered for recurrent cases.

  • Nursing Considerations:

    • Avoid antimotility agents.

    • Watch for recurrence associations with proton pump inhibitors (PPIs).

    • Ensure hydration and electrolyte replenishment, tolerance of oral intake.

    • Implement enteric contact isolation and employ effective cleaning agents in the environment, including UV light when feasible.

Emerging and Reemerging Infections

COVID-19 (SARS-CoV-2)

  • Characteristics:

    • Novel coronavirus causing respiratory illness; spread via respiratory droplets.

    • Risk factors include age > 65, chronic conditions, ethnicity, homelessness, pregnancy, and living with disabilities.

    • Evolves from coronaviruses found in animals, such as Severe Acute Respiratory Syndrome and Middle East Respiratory Syndrome.

  • Signs and Symptoms:

    • Fever, chills, shortness of breath (SOB), fatigue, loss of taste/smell, nausea, vomiting, diarrhea.

    • Various variant strains present.

  • Diagnosis: Via PCR and antigen tests for current infection; antibody testing can determine past infections.

  • Treatment:

    • Focus on preventing spread, may include intensive care measures for severely ill patients (CRRT, oxygenation, ventilation).

COVID-19 Vaccines

  • Types:

    • Pfizer-BioNTech: Approved for age 6 months +, multi-step regimen with boosters.

    • Moderna: Similar approval and recommendation as Pfizer.

    • Novavax: Approved for ages 12 years and older, also multi-step.

  • Note: As of May 2023, Johnson & Johnson’s Janssen vaccine is no longer available in the U.S.

  • Resources: Refer to the CDC website for specific vaccine schedules and recommendations.

Long COVID/Post-COVID Conditions

  • Characteristics: Outcomes that persist long after infection; more common in patients with severe cases of COVID-19.

    • 13.3% report symptoms at one month post-infection; 2.5% at three months.

    • Symptoms include:

    • Tiredness/fatigue impairing daily function.

    • Symptoms aggravating after physical or mental effort.

    • Additional symptoms: fever, difficulty breathing, persistent cough, chest pain, heart palpitations, brain fog, headaches, sleep disturbances, mood changes (anxiety/depression).

    • Gastrointestinal discomfort (diarrhea/stomach pain), joint/muscle pain, rash, menstrual cycle disruptions.

Other Recent Emerging Infections

  • Characteristics:

    • Infections maintaining zoonotic transmission from animals to humans.

    • Examples of emerging infections:

    • Monkeypox: Symptoms include rash and flu-like symptoms. No specific treatments yet, manage symptoms.

    • Zoonotic influenzas (H1N1, H5N1): Antiviral treatment preferred; isolation recommended.

    • Zika Virus: Transmitted by mosquitoes and sexually; associated with birth defects during pregnancy; symptom management encouraged.

    • Other CNS-affecting viruses: Described with severe symptoms and may lead to neurological complications.

Reemerging Infections

  • Measles: Highly contagious airborne virus, vaccine-preventable. Symptoms include high fever and rash appearing after contact. Complications are severe in young children; management via MMR vaccination.

  • Polio: Life-threatening viral infection impacting the spinal cord, leading to paralysis; asymptomatic in most cases. Vaccination programs prevent widespread outbreaks but vigilance is crucial, especially in low vaccination areas.

  • Tuberculosis: Preventable yet remains a global killer. Rates dramatically decreased in 2020 due to COVID but have resurged. Vaccination and awareness are essential for prevention.