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Microbiology Exam 3 Review: Pathogenesis, Epidemiology, Vaccines, Antimicrobials

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Terms in this set (23)

  • What are the 6 steps of pathogenesis?

    The 6 steps are: Portal of Entry, Adherence, Colonization, Invasion, Host Damage, and Host Exit. Each step involves mechanisms that allow the pathogen to enter, attach, multiply, invade tissues, cause damage, and exit to infect others.

  • Define normal flora and opportunistic pathogens.

    Normal flora are microbes normally found on or in the body without causing disease. Opportunistic pathogens cause disease when the host's defenses are compromised or they enter sterile areas.

  • What is a virulence plasmid?

    A virulence plasmid is a plasmid carrying genes that enhance a microbe's ability to cause disease, such as toxins or adhesion factors.

  • Explain the difference between endotoxin and exotoxin.

    Endotoxins are lipopolysaccharides (Lipid A) from Gram-negative bacteria's outer membrane causing inflammation. Exotoxins are proteins secreted by bacteria that target specific cells, often highly toxic.

  • What is antigenic variation?

    Antigenic variation is the ability of a pathogen to alter its surface proteins to evade the host immune response.

  • Define epidemiology and its importance.

    Epidemiology is the study of disease distribution and determinants in populations, essential for controlling outbreaks and understanding disease patterns.

  • What is the difference between endemic, epidemic, and pandemic?

    Endemic: constant presence of a disease in a population.
    Epidemic: sudden increase in cases in a region.
    Pandemic: worldwide epidemic.

  • List 5 major modes of disease transmission with examples.

    1. Direct contact - e.g., HIV
    2. Droplet - e.g., Influenza
    3. Airborne - e.g., Tuberculosis
    4. Food and water - e.g., Salmonella
    5. Arthropod vectors - e.g., Malaria

  • What is the incubation period and prodromal period?

    Incubation period is the time between infection and symptom onset.
    Prodromal period is the early phase with mild symptoms before full disease develops.

  • Why do asymptomatic diseases often spread more easily?

    Because infected individuals show no symptoms, they unknowingly transmit the pathogen to others, making control difficult.

  • What are the two main specific immune cells and their functions?

    T cells mediate cellular immunity and kill infected cells.
    B cells produce antibodies for humoral immunity.

  • How do vaccines create immune memory?

    Vaccines expose the immune system to antigens, activating B and T cells to form memory cells that respond faster upon real infection.

  • Name and describe major vaccine types with examples.

    Live attenuated (e.g., MMR) use weakened pathogens.
    Inactivated (e.g., Salk polio) use killed pathogens.
    Toxoid (e.g., DTaP) use inactivated toxins.
    Subunit/recombinant (e.g., Hib) use parts of pathogens.

  • What is selective toxicity in antimicrobials?

    Selective toxicity means the drug kills or inhibits microbes without harming the host.

  • Define therapeutic index and its significance.

    Therapeutic index is the ratio of toxic dose to therapeutic dose; a higher index means safer drugs.

  • Difference between bactericidal and bacteriostatic drugs.

    Bactericidal drugs kill bacteria.
    Bacteriostatic drugs inhibit bacterial growth, allowing the immune system to clear infection.

  • What is MIC and how is it used?

    Minimum Inhibitory Concentration (MIC) is the lowest drug concentration that inhibits visible bacterial growth, guiding effective dosing.

  • How do beta-lactam antibiotics work? Give an example.

    They inhibit bacterial cell wall synthesis by targeting penicillin-binding proteins. Example: Penicillin.

  • What is beta-lactamase and its clinical relevance?

    Beta-lactamase is an enzyme produced by bacteria that breaks down beta-lactam antibiotics, causing resistance.

  • Name an antibiotic that inhibits protein synthesis and its mechanism.

    Tetracyclines inhibit bacterial protein synthesis by blocking tRNA attachment to the ribosome.

  • What are sulfa drugs and their mode of action?

    Sulfa drugs are growth factor analogs that inhibit folic acid synthesis in bacteria, blocking DNA synthesis.

  • Explain antimicrobial resistance and one cause.

    Antimicrobial resistance is when microbes survive drug treatment. One cause is genetic mutations that alter drug targets.

  • What is the role of the CDC and WHO in infectious diseases?

    The CDC and WHO monitor, report, and coordinate responses to infectious disease outbreaks globally and nationally.