Bacterial infection Flashcards
(20 cards)
What are the three factors influencing the ability of bacteria to cause diseases?
The ability of bacteria to cause diseases results from a combination of factors, including characteristics of the bacteria itself, environmental conditions, and the status of host defenses.
What is the primary role of protein secretion systems (PSSs) in bacterial pathogenicity?
Protein secretion systems (PSSs) play a crucial role in bacterial pathogenicity by translocating molecules and forming adhesins for attachment to host cells.
Describe the main functions of fibrillar adhesins (FAs) and pili in bacterial infections.
Fibrillar adhesins (FAs) and pili facilitate bacterial colonization and invasion. FAs specifically target host cells, while pili mediate attachment to host cell surfaces.
What is the significance of afimbrial adhesins in bacterial pathogenicity, and which proteins do gram-positive organisms possess on their surfaces?
Afimbrial adhesins enhance bacterial binding to host cells. Gram-positive organisms possess afimbrial proteins, such as those targeting salivary glycoproteins and fibronectin.
How do biofilms contribute to bacterial colonization, and which bacterial species is highlighted for its family of biofilm adherence proteins?
Biofilms contribute to bacterial colonization on both biotic and abiotic surfaces. Staphylococcus aureus is highlighted for its family of biofilm adherence proteins.
What is the role of bacterial lectins, and why are they considered potential targets for immunoprophylaxis?
Bacterial lectins play a role in attachment and induce intracellular changes within host cells. They are highly conserved and considered potential targets for immunoprophylaxis.
How do capsules aid bacteria in avoiding phagocytosis, and what is the relationship between capsule assembly and virulence?
Capsules aid bacteria in avoiding phagocytosis. Capsular strains exhibit enhanced virulence, and capsule assembly is remarkably similar across bacterial species.
Explain how structural proteins, such as lipopolysaccharide (LPS) O side chains, contribute to complement resistance in gram-negative bacteria.
Structural proteins like lipopolysaccharide (LPS) O side chains contribute to complement resistance in gram-negative bacteria by preventing phagocytosis.
How do some bacteria modulate host apoptotic pathways for survival, and which bacterial toxins induce or inhibit apoptosis?
Some bacteria modulate host apoptotic pathways for survival. Examples include Shigella flexneri, Staphylococcus aureus, and their toxins inducing or inhibiting apoptosis.
Give 3 examples of afimbrial adhesion molecules found in Gram positive bacteria, and the bacterium with which they are most commonly associated
- Salivary binding proteins: commensals and pathogens of the oral cavity. Streps and Actinomyces.
- Fibrinonectin binding protein: S. aureus invasion.
- Lipotechoic acid: Strep group A/B bacteria (incl. S. equi equi).
Give an example of an afimbrial adhesion molecule in Gram Negative bacteria
high molecular weight adhesion molecules of Haemophilus influenzae and
Bordetella pertussis.
what are the most common bacterial virulence proteins in both Gram postive and Gram negative bacteria?
Bacterial lecithins
What is the primary function of bacterial lecithins
Attachment
Give 3 intracellular changes that may be induced by bacterial lecithins.
actin rearrangement, cell signalling regulation or secretion of bacterial substances into the host cell.
Give 3 examples of bacterial virulence factors
Capsule
Complement resistance
Apoptosis modulation
How does the O antigen prevent complement activation?
By interaction with sialic acid (capsular component) to prevent the formation of C3 convertase.
How do Streptococcal species avoid complement activation?
Serete enzymes that damage C5a
How do Salmonella spp. prevent complement activation?
rck gene encodes protein that prevents C9 insertion into the bacterial membrane
How does S. equi ss equi prevent complement activation?
By reducing complement deposition on the bacterial surface and enhancing fibrinogen binding on the bacterial surface.
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