Activities of Pathogens Flashcards
What are the differences between primary, principal and opportunistic pathogens?
Primary = when isolated always causes disease Principal = causes infection in otherwise well people with intact defences Opportunistic = causes disease when defences are down
What are virulence factors?
The genetic determinants that allow bacteria to cause disease
What are some examples of virulence factors?
Adherence
Invasion
Immune evasion
Toxins
What are the two extremes on the virulence scale?
Never causes disease
Causes disease with no host defences down
Describe gut flora
Anaerobic
E. coli/ enterococcus faecialis
help digest stuff
What is a pyogenic infection?
Tissue invasion in a sterile site, causing inflammation and pus formation
What is a granulomatous infection?
A granuloma is formed because innate immune system has been over run and adaptive immunity is required
What are the two ways that bacteria can cause intoxication?
Intoxication by changing cell physiology (cholera)
Intoxication by damage (gangrene)
How does bacteria cause immune mediation?
Antigen mimicry
Describe the progression of appendicitis
Appendix becomes obstructed by a faecolith and bacteria propagate
Immune response occurs and appendix becomes inflamed. Once full of dead immune cells and dead bacteria this causes pain (begins at belly button but once parietal peritoneum is reached right lower quadrant)
Chronic inflammation causes appendiceal mass
Ruptures, peritonitis, sepsis, death
Which final way can bacteria induce disease?
Cancer (helicobacter pylori)
What is the pattern that pathogens follow while causing disease?
Get to host Get to and recognise environment Adhere/ interact and compete with other organisms/ host Replicate Be transmitted
How does a pathogen achieve adherence?
Be viable in their environment Be motile Be transmitted to their niche Use chemotaxis Use host targets to bind
How does competition with a host differ from competition with other organisms in an environment?
When competing with a host they must have a strategy to avoid the immune system
When competing with other organisms pathogens are fighting for nutrients and space
How can a complement cascade affect pathogens?
Chemotaxis
Opsonisation
Can make holes in bacteria to increase recognition by immune cells
What is streptococcus pyogenes?
Colonises pharynx in children
Causes pharyngitis and skin infection commonly
Rarely can cause rheumatic fever
What are the symptoms of rheumatic fever?
Fever Painful joints Inflamed heart Circular rash Chorea
What are the two ways that diseases are transmitted?
Direct: Sexual, fecal-oral, droplet, airborne
Indirect: Vector borne, health care worker, transfusion, airborne
What are some precautions for preventing the spread of disease?
Waste management, environmental cleaning, disposal of sharps, gloves and gowns, masks, respirator masks and HAND HYGIENE
What are the three ways to categorise diseases/ pathogens?
Structure
Disease (what it effects)
Transmission (arbovirus, enterovirus, respiratory virus)
How do you diagnose a viral illness?
Serology (see if they have antibodies to it) Clinical (symptoms) Culture (grow it) Visualisation PCR
Definitions of pathogen, infection, colonisation, infectious disease, endogenous disease, exogenous disease and zoonosis go!
Pathogen-microbe capable of causing disease
Infection- microbe established on host
Colonisation- infection with no overt immune response
Infectious disease- Interaction with a microbe that causes damage to the host
Endogenous- infection arising from colonising pathogen/flora
Exogenous-infection arising from other factors
Zoonosis-infectious disease from another animal host
