MicroL10 Biofilms
• Biofilm formation is a survival strategy
- May be the default mode of growth in natural environments where nutrients are limited
Biofilms enable bacteria to live together
- Permits cell-to-cell signaling, genetic exchange
Persister cells:
cells tolerant to antibiotics due to a state of dormancy
Stress response:
inner layers have more time to adapt
biofilm flow chamber system
media bottle, pump, bubble traps, flowcell, effluent-bottle
Altered microenvironment:
nutrient depletion creates zones of altered activity
Slow penetration:
outer layers of biofilm cell absorb damage
biofilms impact
teeth, drinking water, oil recovery, paper manufacturing, medical implants, ship hulls, food processing
Homoserine lactone-
wont be able to reach high enough conecntrations when free floating, but in a biofilm, In a biofilm, if molecules being freely diffused, possinbilty that some cells are gonna influence the whole biofilm, they are talking to one another
Biofilms are a means of microbial self defense
- Cells can resist physical forces, phagocytosis, antibiotics
endocarditis
-chronic infection where staphylococcal biofilms are formed on the surface of heart valves
• More than XX% of all microbial infections involve biofilms
60%
Traditional methods to grow bacteria
Agar plate Liquid culture
The importance of biofilms in medicine
Bacteria that form biofilms cause persistent (chronic) infections. In this state the bacteria can withstand the action of the host defense system as well as the highest deliverable doses of antibiotics.
Why do bacteria form biofilms?
Biofilms are a means of microbial self defense • Biofilm formation allows cells to colonize favorable niches Biofilms enable bacteria to live together • Biofilm formation is a survival strategy
Staphylococcal biofilms
Often associated with biofilm formation on the surface of implanted medical devices
• Biofilm formation allows cells to colonize favorable niches
Cells remain attached to nutrient rich surfaces or in locations where nutrients are continually replenished
viewing biofilms
Light microscope Scanning confocal laser microscope
Pseudomonas aeruginosa and cystic fibrosis • Virulence factors:
P. aeruginosa alters gene expression during biofilm growth • Virulence factors: - Extracellular polysaccharide (alginate) - Extracellular DNA (DNases used in treatment) - Quorum sensing
Pseudomonas aeruginosa and cystic fibrosis
P. aeruginosa colonizes the lung of cystic fibrosis patients & forms biofilms
How do biofilms become so resistant to antimicrobials?
Slow penetration: Stress response: Altered microenvironment: Persister cells: Antimicrobial depletion:
Green fluorescent protein (Gfp)
Tagging of cells, multiple colours Direct monitoring of live cells No need to stain!
A biofilm is
a structured community of bacterial cells enclosed in a self-produced matrix and adhered to an inert or living surface
quorum sensing
ability to reaqct to a crowd of bacteria
Antimicrobial depletion:
adsorption of antibiotics, lack of penetration
Examples of Biofilms
• Pseudomonas aeruginosa and cystic fibrosis • Uropathogenic Escherichia coli and catheter infections • Staphylococcus aureus and endocarditis
Examples of Biofilms living tissues
• Tooth enamel • Heart valves • Lung • Middle ear • Bladder
Examples of Biofilms medical devices
• Urinary catheters • Central venous catheters • Contact lenses • Heart valves • Prosthetic joints
