Pathogenesis And Virulence Flashcards
What are the 5 types of symbiotic relationships
Mutualism, amensalism, commenalism, neutralism, parasitism
How is either population effected in a mutualism symbiotic relationship
Both populations are benefited
How is either population effected in an amensalism symbiotic relationship
One population is harmed and the other is unaffected
How is either population effected in a commensalism symbiotic relationship
One benefits the other is unaffected
How is either population effected in a neutralism symbiotic relationship
Both are unaffected
How is either population effected in a parasitism symbiotic relationship
One benefits and the other is harmed
Define pathogenicity
The ability to produce pathologic changes or disease
Define pathogen
disease producing microorganism
Define Virulence
measure of pathogenicity. Also, involves invasiveness and
pathogenicity
Define toxigenicity
ability to produce toxins
What ways do foetus acquire normal flora
Mouth and nose populated from birth canal,
- skin populated by transfer from parents/ doctors
- intestine and gut flora develops after first meal
What are the differences between primary and opportunity pathogens
- primary causes diseases regardless, whereas opportunistic the disease is caused in compromised hosts
What are the 3 main steps in pathogenic bacteria infection
Exposure, adherence, invasion
What does the exposure stage of pathogenic bacteria infection include
Direct contact surfer from the environment or vectors
- main entry point is mucous membranes
What are the 4 main areas of exposure
Direct contact
From the environment
From vectors
From fomites (inanimate objects)
What does the adhesion stage of pathogenic bacteria infection include
Biofilm formation
- adhesins
What does the invasion stage of pathogenic bacteria infection include
Production of lytic substances that alter host tissue
- penetration of deeper tissues and continued dissemination
What are some main classes of exoenzymes
Nucleases, glycohydrolases, phospholipases, proteases
What is the function of glycohydrolases
Degrades hyaluronic acid that cements cells together to promote spreading through tissues
What is the function of nucleases
Degrades DNA released by dying cells
What is the function of phospholipases
Degrades phospholipid bilayer of host cells
What is the function of proteases
Degraded collagen in connective tissue to promote spread
What are the main aspects of endotoxins
They’re released on bacteria death
- they’re heat stable
What systemic effects are produced by endotoxins
Fevers
- intestinal haemorrage
- inflammation
- stimulates the immune system
What are the main aspects of exotoxins
Soluble
- produced within bacteria ( mainly gram positive)
- may travel away from the site of infection
What are the four types ’ of endotoxins
AB toxins (tetanus, cholera)
- site specific (neurotoxins)
- membrane disrupting (haemolysin)
- superantigens (staphylococcal enterotoxin)
What is the composition difference between endotoxins and exotoxins
Endotoxins are lipid A components whereas exotoxins are made of proteins
What is the source difference between endotoxins and exotoxins
Endotoxins come from gram negative bacteria whereas exotoxins come from primarily gram positive
What is the difference in heat stability between endotoxins and exotoxins
Endotoxins are heat stable whereas exotoxins are more heat liable
What is the difference in the effect on hosts between endotoxins and exotoxins
Endotoxins - General systemic symptoms of inflammation and fever
Exotoxins - specific damage to cells dependant upon receptor mediated targeting of cells
What is the difference in LD50 between endotoxins and exotoxins
. Endotoxins are high whereas exotoxins are low
What are the 3 types of pathogen multiplication
Local, focal, systemic
What is local pathogen multiplication
- small area near entry site
- extensive tissue damage but still localised
What is focal pathogen multiplication
Spreads to a secondary location
/ which leads to a secondary infection
What is systemic pathogen multiplication
Spreads throughout the body
What are the main characteristics of diseases
signs (objective)
- body temp 98.2f
- heart rate 60-100
- blood pressure 90/60 and 120/80
Symptoms
- subjective
Nausea, loss of appetite
What are the main classifications of diseases
Infectious
Iatrogenic
Nosocomial
Zoonotic
Non communicable
Non infectious
What are the five periods of disease
Incubation, prodromal, illness, decline, convalescence
Do incubation periods have a variable length
Yes
What are the features of the incubation period
No signs or symptoms
Variable length
What are the features of the prodromal period
- Multiplication continues
- common signs + symptoms
( too general to diagnose a specific disease
What are the features of the illness period
- Very severe
- most evident
- lack of immune response
What are the features of the decline period
- decrease in the number of pathogens
- decrease in signs and symptoms
- potential to acquire secondary infection
What are the features of the convalescence period
- Patient recovers
- tissue repair leads to normal function
- length of time depends on damage severity, nature of pathogen, and the site of infection
During which periods are infectious diseases contagions
All 5
What is acute infection
- Symptoms develop quickly
- brief typically resolves in less than 6 months
What is chronic infection
Slow onset of symptoms and can worsen over time
- persists beyond 6 months
Which membrane serves as the main portal of entry for pathogens
Mucous
In which disease period does the patient start to get better
Convalescence
What is the name given to infections/diseases acquired from the hospital
Nosocomial
What are exotoxins primarily made up of
Proteins
Lipid A is a type of what toxin
Endotoxins
Tetanus toxin prevents the release of what?
Acetylcholine
Which toxin lyses red blood cells
Haemolysins
What is the name of a disease that’s contracted due to a medical procedure
Latrogenic
What is the measure of pathogenicity
Virulence
What type of infection develops quickly
Acute
Toxic shock is the most characterised……
Superantigen
What enzyme breaks down collagen
Collagenase
