Lecture 10: Medical Microbiology Flashcards
What is infection?
When a parasite is multiplying in/on a host.
Define infectious disease.
Host cannot function normally due to presence of parasite or its products.
What do pathogens do?
cause Disease
What is pathogenicity?
An organism’s ability to cause disease.
Define virulence.
Degree or intensity of pathogenicity, as indicated by morbidity & mortality rates.
List the three factors affecting the outcome of the host/parasite relationship.
- Number of organisms inoculated
- Virulence of organism
- Host’s degree of resistance.
What role does the number of organisms inoculated play in infection risk?
Usually, the higher the number of organisms, the greater the risk of disease.
Usually, the higher the number of organisms, the greater the risk of disease.
Some organisms are so virulent that very low numbers can cause disease.
What factors contribute to a host’s degree of resistance?
- Host’s immune competency
- Host’s lifestyle (sleep, diet, exercise) * Host’s living conditions.
What are the stages of the infectious disease process?
- Incubation Period
- Prodromal Stage
- Illness Period
- Convalescence.
What is infectivity?
Ability of an organism to start an infection.
What are the modes of transmission for communicable infectious diseases?
- Direct (Horizontal, Airborne, Vertical, Vector)
- Indirect (vehicles).
Fill in the blank:
Fomites are _______.
inanimate objects which are contaminated.
What are adhesins?
Molecules that help organisms adhere to surfaces.
What factors determine the ability of an organism to grow in or on a host?
- pH
- O2 content
- Temperature.
What is the role of IgA protease?
Cleaves IgA to help avoid the immune system.
Define invasiveness.
Ability of an organism to spread within the host.
List microbial products involved with invasion.
- H2O2
- NH3
- Collagenase
- Elastase
- Hyaluronidase
- Lecithinase.
What is pathogenic potential?
Ability of an organism to cause symptoms.
Differentiate between infections and intoxications.
- Infections: tissue damage caused by invasiveness or toxins produced within the host. * Intoxications: damage due to toxins produced outside of the host.
What are exotoxins?
Proteins produced by bacteria that can cause damage.
What type of toxin is associated with botulism?
Neurotoxin that inhibits neurotransmitter release.
What are enterotoxins?
Toxins that affect the gastrointestinal tract.
What is the function of superantigens?
Overstimulate the immune system, causing a response similar to endotoxin.
True or False: Endotoxins are proteins.
False
What is the significance of Lipid A in the context of endotoxins?
It activates blood clotting factors leading to septic shock.
What is disseminated intravascular coagulation (DIC)?
Unregulated blood clotting in capillaries leading to multi-organ failure.
How do viral pathogens typically cause damage?
By killing host cells during replication.
What strategy do some viruses use to evade the immune system?
By keeping class I MHC from reaching the cell surface.
