Week 10 Flashcards
(34 cards)
What is a pathogen?
A pathogen is a microorganism capable of causing disease.
What is pathogenicity?
Pathogenicity is the ability of a microorganism to cause disease.
What is symbiosis?
Symbiosis is an association between two or more species.
What are the different types of symbiosis?
Mutualism: Both organisms benefit.
Commensalism: One organism benefits, and the other is neither harmed nor benefited.
Parasitism: One organism (parasite) benefits, and the host is harmed.
What are virulence factors?
Virulence factors are structural or physiological characteristics that help microorganisms cause disease, such as pili, glycocalyx, sucking disks, and toxins.
What are the mechanisms of disease caused by microorganisms?
Attachment: Organisms attach to host tissues and cause damage.
Toxins: Harmful substances that damage host cells.
Enzymes: Released substances that damage surrounding cells.
Inflammation: Triggering immune responses that may result in tissue damage.
What types of damage can viruses cause to cells?
Syncytium: Multiple cells fuse into one large, abnormal cell.
Inclusions: Abnormal structures form inside infected cells.
Cell lysis: The virus bursts open the host cell, destroying it.
Cell transformation: Some viruses turn normal cells into cancerous cells.
Cytopathic effect: Visible changes in infected cells, such as shape changes or fusion.
How do bacteria cause disease?
Adhesion: Bacteria stick to host cells using adhesion molecules.
Colonization: Bacteria begin to grow on body surfaces, particularly epithelial linings.
Invasion: Some bacteria can enter and multiply inside body tissues, spreading infection.
What is the role of bacterial enzymes in pathogenesis?
Hyaluronidase: Breaks down hyaluronic acid, allowing bacteria to penetrate deeper tissues.
Endotoxins: Found in the outer membrane of Gram-negative bacteria and can cause fever and shock.
Exotoxins: Secreted by bacteria, such as hemolysins, which destroy red blood cells.
What is the difference between hemolysins and their effects?
Alpha-hemolysins: Partial breakdown of red blood cells, leaving a greenish discoloration on blood agar.
Beta-hemolysins: Complete destruction of red blood cells, creating clear zones around bacterial colonies.
What are enterotoxins and neurotoxins?
Enterotoxins: Act on tissues in the gut.
Neurotoxins: Act on nervous tissue, such as botulinum toxin which prevents muscle contraction.
What are toxoids?
Inactivated toxins used in vaccines to safely trigger an immune response without causing disease.
What are Koch’s postulates? What are the 4 steps?
Koch’s postulates are a series of criteria used to prove that a specific microorganism causes a disease:
The suspected pathogen must be found in every case of the disease.
The pathogen must be isolated and grown in pure culture.
The cultured microbe must cause the same disease when introduced to a healthy host.
The same pathogen must be re-isolated from the newly infected host.
What is anthrax and its forms?
Anthrax is caused by Bacillus anthracis and can occur in three forms:
Cutaneous anthrax: Endospores enter through the skin, causing lesions.
Respiratory anthrax: Inhalation of spores leads to pulmonary infection.
Intestinal anthrax: Ingestion of spores causes intestinal hemorrhaging.
What is zoonosis?
refers to diseases transmitted from animals to humans, such as anthrax, often spread by infected livestock.
How did Koch’s postulates help prove Helicobacter pylori causes ulcers?
Found in ulcer patients: H. pylori was present in most patients with ulcers.
Isolated and cultured: Marshall and Warren isolated it from patients.
Self-experiment: Marshall drank the bacteria to prove it could cause disease.
Re-isolated: The same bacteria was found in Marshall’s stomach.
How does Helicobacter pylori survive in the stomach?
Urease: Breaks down urea into ammonia, neutralizing stomach acid.
Adhesins: Help the bacteria stick to stomach cells.
Flagella: Allow movement through the mucus layer in the stomach.
What is the difference between communicable and non-communicable diseases?
Communicable disease: Spread from one host to another.
Non-communicable disease: Acquired by alternative routes, such as tooth decay.
What are portals of entry and exit for pathogens?
Pathogens can enter through the respiratory tract, gastrointestinal tract, cuts, or mucous membranes, and exit through similar routes, including bodily fluids.
What is epidemiology?
The study of the distribution and determinants of health-related events in populations.
What is an endemic disease?
An endemic disease is constantly present in a given population, with a low number of cases and low severity.
What is an epidemic disease?
A sudden increase in the number of cases of a disease above the expected level in a population over a short period.
What is a pandemic disease?
an epidemic that spreads over a wide geographic area, often crossing international boundaries.
What is the reproduction number (Ro)?
is the average number of people one infected person will spread a disease to. It helps determine the potential for an epidemic or pandemic.
