Medical Microbiology Flashcards
What is the main purpose of epidemiology?
To study the distribution, determinants, and control of diseases within populations to improve public health and prevent disease outbreaks.
Define the epidemiological term epidemic.
A sudden increase in the number of cases of a disease above what is normally expected in a particular area or population.
Define the epidemiological term endemic.
The constant presence and/or usual prevalence of a disease within a specific geographic area or population.
Give an example of a common source epidemic.
Cholera (spread through contaminated water).
Give an example of a host-to-host epidemic.
Influenza (spread from person to person through droplets).
Name the causative agent of tuberculosis (TB).
Mycobacterium tuberculosis.
What is the cellular morphology of Mycobacterium tuberculosis?
Gram-positive, acid-fast, rod-shaped bacterium.
Name three factors which can affect the transmission of TB.
- Close contact with an infected person.
- Environmental factors like ventilation and air circulation.
- Immune status of the individual.
Who was the German scientist who determined the causative agents for infectious diseases?
Robert Koch.
Name a limitation of Koch’s postulates.
Some pathogens cannot be cultured in the laboratory.
Name another limitation of Koch’s postulates.
Not all individuals infected with a pathogen may show symptoms.
Describe the specificity feature of the adaptive immune response.
The immune system can recognize and respond to specific pathogens.
Describe the memory feature of the adaptive immune response.
The immune system ‘remembers’ a pathogen, providing quicker and stronger responses upon re-exposure.
Describe the diversity feature of the adaptive immune response.
The immune system can recognize a vast array of antigens due to a large number of immune receptors.
What are the humoral components of adaptive immunity?
Mediated by B cells and the antibodies they produce.
What are the cellular components of adaptive immunity?
Mediated by T cells (including helper T cells and cytotoxic T cells).
What is the first stage of phagocytosis?
Chemotaxis: The phagocyte is attracted to the site of infection by signals released by pathogens or damaged tissue.
What is the second stage of phagocytosis?
Adherence: The phagocyte attaches to the pathogen through receptors that recognize specific components.
What is the third stage of phagocytosis?
Ingestion: The phagocyte engulfs the pathogen by extending its cell membrane around it to form a phagosome.
What is the fourth stage of phagocytosis?
Digestion: The phagosome fuses with a lysosome, forming a phagolysosome, where enzymes break down the pathogen.
What is the fifth stage of phagocytosis?
Exocytosis: The waste products of digestion are expelled from the phagocyte.
