Lecture 2 Flashcards
What 5 factors determine the severity of a disease?
- Inoculum size
- Strain of bacteria
- Susceptibility of host
- Threshold for disease production
- Tissue/function affected
What are 4 factors influence the strength of the immune response
- Ability to colonize
- Damage potential
- Duration of infection
- Number of pathogens
Name 8 Virulence Factors
- Adherence
- Invasion
- Capsule
- Metabolic byproducts
- Toxins (endotoxins, exotoxins and superantigen)
- Excess inflammation
7.Evasion of immune response - Resistance to antibiotics
What are the three types of bacteria?
Commensal, Opportunistic, and Virulent
What are commensal bacteria?
Bacteria that coexist with the host without causing harm
What are opportunistic bacteria?
Bacteria that normally do not cause disease but can become pathogenic under certain conditions
Give an example of an opportunistic bacterium that can become virulent.
Clostridium difficle
What is a Pathogenicity Island?
A cluster of virulence genes within the bacterial genome that enhances pathogenicity
What 4 major steps of bacterial infection
- Enter
- Colonize
- Destroy
- Evade
What are the two main types of bacterial entry into the body?
Natural openings and barrier breaches
look over slide 13,14,15
adhesion defintion
bacteria must bind to host cell surfaces
What are adhesins?
Bacterial proteins that interact with host receptors
* Commonly found on tips of fimbriae (pili)
* Also associated with bacterial surface (Ex. Lipoteichoic acid)
What is the primary component of a bacterial biofilm?
Polysaccharides
give me 4 points on bioflim production
- Primarily composed of polysaccharides
- Binds cells of a colony together
- Produced when colony number reaches a threshold
(quorum) - Protects colony from host defenses, antibiotics
* Ex. Dental plaque, medical appliances
How do invasive bacteria enter host tissues?
By destroying barriers and using effector proteins to facilitate transport
What role do effector proteins play in bacterial invasion?
Effector proteins facilitate transport
How does E. coli promote invasion?
E. coli secrete proteins that form docking station
How does Salmonella promote its uptake into host cells?
Salmonella secrete proteins that promote vesicular uptake
What type of cells do some bacteria use for transport across the intestinal barrier?
M Cells
What are two main ways bacteria cause tissue destruction?
Direct damage through metabolic byproducts and degradative enzymes, and indirect damage by triggering excessive immune responses.
Name three bacterial metabolic byproducts that contribute to tissue destruction
Acids, gases, and other toxic substances
Name three degradative enzymes involved in tissue destruction
Collagenase, hyaluronidase, and fibrinolysin
What are two ways bacteria induce cell death?
Apoptosis (programmed cell death) and lysis (cell rupture)
How can the immune response contribute to tissue destruction?
Excessive inflammation and immune reactions can damage host tissues indirectly
What types of bacteria produce exotoxins?
Both Gram-positive and Gram-negative bacteria
Where are exotoxin genes often encoded?
On plasmids or bacteriophages
Name 3 degradative enzymes
- Hemolysins
- Cytolytic toxins (α-toxin)
- Pore-forming toxins (streptolysin)
True/False
A-B exotoxins are single-component toxins that enter host cells and cause damage
False – A-B exotoxins are dimeric
- B subunit binds cell surface receptor
- A subunit transferred in cell interior to do damage
slide 21 didnt know how tomake card for it
What is the primary function of diphtheria toxin?
It blocks protein synthesis in host cells
How many diphtheria toxin molecules are needed to destroy a cell?
A single molecule can destroy a cell
What cellular factor does diphtheria toxin irreversibly block?
Irreversible block of EF-2
What is the primary effect of cholera toxin on host cells?
It causes the overproduction of cAMP
How does cholera toxin increase cAMP levels?
It modifies host adenylate cyclase
What is the primary effect of botulinum toxin?
It causes paralysis
How does botulinum toxin induce paralysis?
It blocks acetylcholine (ACh) release at the neuromuscular junction (NMJ)
Superantigens
simultaneously bind TCRs and MHC II
Name 4 outcomes of superanitgen activation
- Activate large numbers of T cells
- T cells release a cytokine storm
- Causes autoimmune-like responses
- Can also lead to T cell apoptosis
Are endotoxins cell wall components of Gram(+) and Gram(-) bacteria?
yes
What is an example of an endotoxin from Gram-negative bacteria?
Lipid A component of lipopolysaccharide (LPS)
What are examples of endotoxin-like molecules in Gram-positive bacteria?
Lipoteichoic acid and peptidoglycan
true or false
Endotoxins are recognized by immune cell receptors such as TLRs and CD14 on macrophages, neutrophils, and B cells
true
true or false
Endotoxins inhibit the production of acute-phase cytokines like IL-1, IL-6, and TNF-α
False – Endotoxins stimulate the production of these cytokines
true or false
Endotoxins can cause coagulation and B cell proliferation.
True
true or false
High levels of endotoxins can cause Toxic Shock
true
go over slide 28
