MICR223_L15_biofilms

What is the primary objective of studying biofilms in bacterial pathogens?

To appreciate the ways biofilms contribute to virulence.

What is the initial stage of biofilm formation by Staphylococcus aureus?

Bacterial cells attach to surfaces and replicate.

What role does the Agr regulatory system play in S. aureus biofilm development?

It promotes the structuring and detachment stages.

How do biofilms resist cell loss?

Cells in a biofilm are tightly stuck together.

Why are bacteria in the interior of a biofilm tolerant to antibiotics?

They are metabolically dormant or express factors that prevent killing.

What typically happens to phagocytes trying to ingest biofilms?

They make unsuccessful attempts to ingest biofilms.

Which bacterium is known for colonizing the lungs of cystic fibrosis patients?

Pseudomonas aeruginosa.

Name one disease associated with Staphylococcus aureus.

Toxic Shock Syndrome (TSS).

Describe the role of Fibronectin Binding Protein (FnBP) in biofilm formation.

It mediates the binding of S. aureus to the fibronectin coating on medical implants.

What is Polysaccharide Intercellular Adhesin (PIA)?

A positively charged polymer that helps bacteria stick together in a biofilm.

What is the effect of Phenol Soluble Modulins (PSMs) in biofilms?

They promote structuring and detachment of biofilms.

How is detachment of biofilm pieces mediated?

Through an unknown mechanism involving PSMs.

What does the Agr system regulate in S. aureus?

The expression of PSMs and toxins.

How does quorum sensing relate to biofilm maturation?

It regulates the transition from low to high AIP concentration, triggering PSM expression.

What role does AIP play in the Agr system activation?

It interacts with AgrC to activate the cascade of gene expression.

How does RNAIII facilitate toxin gene expression in high AIP concentrations?

It allows the Shine-Dalgarno sequence to bind with the ribosome, initiating translation.

What happens to AIP levels during biofilm formation?

AIP levels increase as biofilms become denser.

How do different groups of S. aureus AIPs interact during co-infection?

An AIP from one group can interfere with AgrC activation in another group.

What is the significance of the Shine-Dalgarno sequence in gene expression?

It is crucial for the initiation of translation of mRNA.

What are 'persister' bacteria?

Bacteria within biofilms that exhibit antibiotic tolerance and can lead to relapsing infections.

How does nutrient availability affect biofilm susceptibility to drugs?

Low nutrient concentrations can lead to poor susceptibility to certain drugs.

What is the contribution of surfactants to biofilm structure?

They can aid in the structuring by having both hydrophobic and hydrophilic properties.

What occurs during the maturation stage of S. aureus biofilms?

Formation of an extracellular matrix that helps bacteria stick together.

What is the proposed consequence of AIPs in treating S. aureus infections?

AIPs have potential as drugs to interfere with biofilm formation.

How do antibiotic tolerance mechanisms differ in biofilm cells compared to planktonic cells?

Biofilm cells may express factors that protect them against antibiotics, unlike planktonic cells.

What structural feature of biofilms allows for nutrient delivery?

The formation of water channels within the biofilm.

What types of environments can Staphylococcus aureus colonize?

Medical implants and the skin and anterior nares in humans.

Why do S. aureus biofilms pose significant clinical challenges?

They are resistant to phagocytosis and antibiotics.

How is biofilm density monitored?

By tracking AIP concentration and its effects on Agr system activation.

What implications do AIPs have for the future of infection treatment?

They may serve as therapeutic agents to prevent or treat S. aureus infections.

What phenomenon can occur when different S. aureus groups co-infect?

Interference in the Agr activation can happen between AIPs from different groups.