Lecture 19

Vaccine Hesitancy

• Definition: Reluctance or refusal to vaccinate despite the availability of vaccines.

• Aristotle’s Persuasion Elements:

  • Trustworthy messenger
  • Sense-making arguments
  • Emotional connection
  • A worthy goal for the messenger

• Strategies to Address Vaccine Hesitancy:

  • Patient-Provider Interactions:
  • Listen and respect concerns
  • Build common ground
  • Be honest about vaccine imperfections
  • Diversity in Healthcare:
  • Increases trust when healthcare professionals reflect the community's diversity
  • Transparency in Healthcare:
  • Reducing private industry influence and being clear about relationships with pharmaceutical companies.

Diagnostic Tools of Immunology

Immunoprecipitation

• Definition: A serology technique used to measure small soluble antigens based on the dependence of antigen-antibody ratios.
• Concepts:
  • Antigen Excess: When there is too much antigen relative to antibody.
  • Antibody Excess: When there is too much antibody relative to antigen.
  • Equivalence: The optimal ratio where the number of antigenic sites equals the number of antibody-binding sites.

Agglutination

• Definition: A method to measure insoluble antigens on whole cells through cross-linking.
• Applications:
  • Blood Typing: Mixing patient blood with known antibodies to detect clumping, indicating a positive reaction.
  • Pathogen Identification: Adding antibodies to pathogens to observe clumping, confirming the presence of specific antigens.

Enzyme-Linked Immunosorbent Assay (ELISA)

• Functionality:
  • Detects either antibodies or antigens in samples.
• Types:
  • Direct ELISA:
  • Detects pathogen antigens directly in the patient’s sample.
  • Involves immobilizing antigen to a plate and using enzyme-linked antibodies for detection.
  • Indirect ELISA:
  • Detects antibodies against a pathogen using a known antigen on the assay plate to capture patient antibodies.
  • Requires that antibodies have formed, meaning that it is best used for past infections.
  • Sandwich ELISA:
  • Involves capturing antigen using a specific antibody and detecting it with a secondary antibody conjugated to an enzyme.
• Limitations:
  • High levels of antigen required for direct ELISA.
  • Indirect ELISA may not work for recent infections due to the time needed for antibody production.

Importance of Clinical Microbiology

• Purpose:
  • Identifying the infectious agent of disease is crucial for effective treatment and prevention of complications.
• Key Reasons:
  • Guide antibiotic treatment based on susceptibility.
  • Prevent antibiotic resistance, e.g., Neisseria gonorrhea resistance to penicillin.
  • Surveillance of epidemiological outbreaks.
• Steps for Identification:
  • Collect specimens based on signs/symptoms, medical and travel history, and knowledge of local outbreaks.
  • Use clinical tests for pathogen identification, including biochemical methods and serological assays.

Specimen Collection

From Sterile Areas

• Types of Samples:
  • Blood, cerebrospinal fluid (CSF), pleural fluid, synovial fluid, and internal organ tissues.
• Key Procedures:
  • Blood cultures: Collected via venipuncture, careful to avoid contamination.
  • CSF: Obtained through lumbar puncture, requiring sterile techniques.

From Nonsterile Areas

• Types of Samples:
  • Throat/nasopharynx, sputum, stool, skin lesions, and deep wounds.
• Techniques:
  • Sterile swabs for throat cultures, special mediums for transport, and using selective media to inhibit normal microbiota growth in cultures.

Mpox (Monkeypox)

Overview

• Caused by: Monkeypox virus (MPXV), an enveloped dsDNA virus from the Poxviridae family.
• Current outbreak: Notable for the IIb subclade.

Transmission and Symptoms

• Transmission:
  • Through broken skin, mucous membranes, or maternal to fetal transmission.
• Symptoms:
  • Fever, sore throat, headaches, muscle pain, lymphadenopathy;
  • Characteristic skin lesions evolving from flat bumps to blisters.

Complications

• Risk factors include:
  • Young children, pregnant women, and immunocompromised individuals.
• Potential complications:
  • Secondary infections, pneumonia, sepsis, encephalitis, and possible death.

Treatment and Prevention

• Treatment:
  • Supportive therapy is crucial.
  • Monitoring of high-risk individuals.
• Prevention:
  • Vaccination for those at high risk or after exposure.
  • Strict hygiene practices including isolation of symptomatic patients.