Mechanisms of Bacterial Pathogenesis Flashcards
Examples of disease states where host clears the pathogen before symptoms of disease are noted
asymptomatic, inapparent, subclinical
What is a communicable infection?
An infection that can be passed from host to host
Where do noncommunicable infections come from?
the environment
Describe the action of a latent infection
an infection in which the disease subsides but microorganisms remain in the body and can restart disease later
What is a chronic carrier?
a host in which the disease continues without symptoms and the host continues to shet the pathogen indefinitely
Are pathogens, parasites?
Yes, they harm the host by taking its resources
What are all viruses?
Obligate intracellular parasites
Most bacteria are?
facultative intracellular parasites
What is the virulence, LD50, and ID50 of nonpathogens?
Low virulence and extremely high LD and ID50
What is the virulence, LD50, and ID50 of opportunistic pathogens?
Low virulence, High LD50 and slightly lower ID50
Who do opportunistic pathogens most commonly infect?
immunosuppressed/ injured hosts
Give examples of Opportunistic Pathogens
Psuedomonas, eterobacter, klebsiella
What is the virulence, LD50, and ID50 of highly pathogenic ?
High virulence and mid to low LD50
What is virulence a measure of?
numerical measure of pathogenicity. it is measured by ID50 and LD50
What enhances pathogenicity?
virulence factors
What are the main functions of virulence?
1- Survival in extreme environments 2- Adhesion to host surfaces 3- Immune evasion 4- Take over host cells 5- Poison the host 6- Endotoxins
What types of environments can pathogens adapt themselves to in order to increase virulence?
pH extremes, resistance to drying and detergents, and low iron environments
What are some adhesion mechanism of pathogens?
Pili, slime layer
What helps pathogens resist phagocytosis?
Capsules (gram - mostly)
Name some immune system evasion tactics
Induce apoptosis of macrophages, IgA proteases, antigenic variation
How do pathogens take over host cells?
T3SS and T4SS, endosome escape routes, and actin polymerization pathway for cell to cell spread
What are exotoxins?
secreted polypeptides that are encoded on accesory DNA that come in on plasmids or by phage infectin
How are exotoxins released?
secreted from the cell or injected by T3SS
Structure of exotoxins?
A-B subunit system. A is toxic and B helps bind to the cell
What are the functions of exotoxins?
1- interfere wtih signal transduction
2- cause depolymerization of actin
3- act as supertoxins
What is a good vaccine item?
Heat or chemically inactivated exotoxin. The toxin becomes a toxoid.
What are endotoxins?
intrinsic to the surface of bacteria and cause immunogenic symptoms
What are examples of endotoxins?
Gram (-) LPS, Gram (-) LOS, and Gram (+) teichoic acids
What is the timeline of infectious disease?
1- incubation period
2- prodromal period
3- specific-illness period
4- recovery convalescence
Stages of bacterial pathogenesis.
1- Transmission of pathogens
2- attachment of pathogens to host surfaces
3- Invasion, inflammation, intracellular survival
4- survival inside host cells
5- poisoning the host (exotoxins)
What is the pyogenic inflammatory immune response?
pus forming, predominantly neutrophils
What is the granulomatous inflammatory response?
macrophages kill most of the bacteria but some can survive inside macrophages within a granuloma
