Study guide notes Flashcards
What are the 5 steps involved in microbial disease?
- Portal of entry
- Attachment
- Surviving Host defenses
- Causing disease
- Portals of exit
These steps outline the process through which pathogens establish infection in a host.
What are phagocytes?
Cells that engulf and destroy host pathogens by means of enzymes and antimicrobial chemicals
Phagocytes play a crucial role in the immune response.
What are antiphagocytic factors?
- Leukocidins: kill phagocytes outright
- Extracellular surface layer (slime or capsule): makes it difficult for the phagocyte to engulf the pathogen
- Some bacteria survive inside the phagocyte
These factors help pathogens evade the immune system.
What is endotoxin?
Lipopolysaccharide (LPS) that is part of the outer membrane of gram-negative cell walls
Endotoxin has a variety of systemic effects on tissues and can lead to severe health issues.
What are the effects of endotoxin?
- Causes fever
- Causes inflammation
- Causes hemorrhage
- Causes diarrhea
Endotoxin can lead to fatal endotoxic shock in severe cases.
What is the infectious dose?
Minimum number of microbes needed to cause infection
Smaller infectious doses indicate higher virulence.
Define pathogenicity.
An organism’s potential to cause disease
Pathogenicity is a measure of how likely a microbe is to cause disease.
Define virulence.
Relative severity of a disease caused by a particular microbe
Virulence is determined by the microbe’s ability to establish itself in a host and cause damage.
What is a virulence factor?
Any characteristic or structure of the microbe that contributes to its ability to establish itself in the host and cause damage
Virulence factors can include toxins, surface proteins, and other elements that aid infection.
What are opportunistic pathogens?
Pathogens that cause disease when the host’s defenses are compromised
They can also establish themselves in parts of the body that are not natural to them.
What is a reservoir in the context of infectious diseases?
Primary habitat of pathogens (humans, animals, soil, water)
Reservoirs are essential for the survival and transmission of pathogens.
What is a carrier?
An individual who inconspicuously shelters a pathogen and spreads it to others without any notice
Carriers can transmit infections without showing symptoms themselves.
What are healthcare-associated infections (HAIs)?
Infectious disease acquired or developed during a hospital or health care facility stay
HAIs are a significant concern in healthcare settings.
What are the common pathogens associated with HAIs?
- C. difficile
- S. aureus
- Klebsiella
- E. coli
- Enterococcus
These pathogens are frequently responsible for infections acquired in healthcare facilities.
What is the role of an infection control officer?
Implements proper practices and procedures, tracks potential outbreaks, identifies breaches in asepsis, and trains health care workers in aseptic techniques
They are crucial for preventing and controlling infections in healthcare settings.
What is the difference between incidence and prevalence?
- Prevalence: Total existing cases; snapshot
- Incidence: New cases over a certain period of time
These terms are essential in epidemiology to measure disease occurrence.
Define mortality rate.
Deaths due to disease
Mortality rate provides insight into the lethality of a disease.
Define morbidity rate.
Number of persons afflicted with infection
Morbidity rate helps assess the impact of a disease on a population.
What is chemotaxis?
Movement of a cell toward a chemical stimulus
Positive chemotaxis is crucial for phagocytes to locate invading microbes.
What are the stages of phagocytosis?
- Chemotaxis
- Adherence
- Ingestion
- Digestion
- Elimination
These stages describe the process by which phagocytes engulf and destroy pathogens.
What are granulocytes?
White blood cells that contain large granules that stain different colors based on the dye used
Granulocytes include basophils, eosinophils, and neutrophils.
What are the three lines of defense in the immune system?
- First Line of Defense: Innate defenses; physical and chemical barriers
- Second Line of Defense: Activated when pathogens bypass the first line; includes phagocytes and chemicals
- Third Line of Defense: Humoral and cell-mediated immune responses
Each line of defense plays a distinct role in protecting the body from infection.
What is the role of T cells?
Make copies of themselves and secrete cytokines affecting other cells
T cells are essential components of the adaptive immune response.
What is the difference between an antigen and an antibody?
- Antigen: Anything stimulating a specific immune response
- Antibody: Activates complement and natural killer cells
Understanding these terms is fundamental to immunology.
