Biofilms

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What are sessile bacteria?
Bateria that is able to attach to surfaces and each other
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What is a biofilm?
Morphologically heterogenous are multi-layered matrices commonly established by sessile bacteria
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What happens when environmental conditions change which threatens a mature biofilm?
The bacteria respond by returning to their free-living lifestyle (planktonic) enabling them to disperse and re-colonise at an alternative niche
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What are the applications of biofilms?
To purify water in water treatment plants
To breakdown chemicals, often toxic
To produce biomolecules, including drugs
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Where can biofilms be found?
On humans
Animals
Plants
Environmental, industrial or medical systems
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What is the biofilm phenotype?
A slower growth rate
Increased antibiotic resistance
Elevated frequency of lateral gene transfer
Chemotaxis
Motility
Transport/Uptake systems
DNA release
Polysaccharide production (EPS)
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What function do polysaccharides play in biofilms?
They determine biofilm architecture by protecting the cells from the host defences and antimicrobials
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What does the biofilms matrix consist of?
Living cells, dead debris, proteins, polysaccharides, surfactants, lipids, glycoproteins, extracellular DNA, 97% water
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What are fimbriae?
Thin and short
Found the gram -ve and +ve bacteria
Used to adhere to cells
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What are pili?
Longer and thicker
Found in gram -ve bacteria
Used for genetic transfer
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What makes biofilms resistant to antibiotics?
Poor antibiotic penetration
Nutrient limitation
Slow growth
Adaptive stress responses
Formation of persister cells
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What are persister cells?
A mechanism for population survival in the event of an unexpected challenge from antimicrobial agents or other environmental stresses
They forgo rapid growth and division and remain slow-growing in order to be tolerant of antimicrobials. They can then gro
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What are the four components of a flow cell?
The nutrient supply
An access port
The flow cell
The waste disposal container
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What is quorum sensing?
A process of bacterial communication which involves producing, releasing, detecting and responding to small hormone-like or diffusible molecules
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What are the hormone-like or diffusible molecules called?
Autoinducers
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What does quorum sensing control?
Symbiosis
Virulence
Conjugation
Antibiotic production
Motility
Sporulation
Biofilm formation
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What are the two systems in P. aeruginosa that control quorum sensing?
LasI - encoded acyl-HSL synthase
LasR - encoded transcriptional activator
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What are some device-related infections caused by biofilms?
Ventricular derivations
Contact lenses
Endotracheal tubes
Central vascular catheters
Prosthetic cardiac valves, pacemakers and vascular grafts
Peripheral vascular catheters
Urinary catheters
Orthopaedic implants and prosthetic joints
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What are some tissue-related infections caused by biofilms?
Chronic otitis media, chronic sinusitis
Chronic tonsilitis, dental plaque, chronic laryngitis
Endocarditis
Lung infection in cystic fibrosis
Kidney stones
Biliary tract infections
Urinary tract infections
Osteomyelitis
Chronic wounds
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What is Enterococcus faecalis (nosocomal)?
High levels of antibiotic resistance
Facultative anaerobe can cause life-threatening infections
Biofilms on dental root canals, urethral catheters, urethral stents and heart valves
Clinical isolates have the ability to form a biofilm in vitro (test tube)
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What is the most common biofilm found on humans?
Dental plaque
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What are some examples of primary colonisers of dental plaque?
Gram positives
Streptococcus sanguis
Streptococcus mutans
Actinomyces viscosus
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What are some examples of secondary colonisers of dental plaque?
Gram-negatives
Fusobacterium nucleatum (oral)
Preuotella intermedia
Capnocytophaga species
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What are some examples of tertiary colonisers of dental plaque?
Gram-negatives
Porphyromonas gingivalis
Campylobacter rectus
Eikenella corrodens
Actinobacillus actinomycetemcomitans
Oral spirochetes (treponema species)
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How does campylobacter species promote the growth of porphyromonas gingivalis?
Succinic acid
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How do streptococcus and actinomyces promote the growth of campylobacter?
Formate
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How does fusobacterium promote the growth of spirochetes?
Produce thiamine and isobutyrate
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How do kidney stones form?
1. Bacterial adhesion
2. Microcolony formation and secretion of extracellular polysaccharide
3. Crystal formation
4. Planktonic bacteria detach
5. Planktonic bacteria attach to pre-existing crystals, the cycle repeats until a stone is formed
6. Stone cont
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What is cystic fibrosis?
Mutation in chloride channel in epithelial cells
1st stage - intermittent infections
2nd stage - permanent infection with Pseudomonas aeruginosa
Mucoid type - overproduce alginate
Antibiotic resistance
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What are some short term antibiofilm agents?
Lactoferrin
Xylitol
Gallium
Farnesol
Deferoxamine
EDTA
Dispersin B
Fatty acid gel
Nitric oxide
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What are some long term antibiofilm agents?
Quorum sensing inhibitor
RNA II inhibitory peptide
Furanones
Autoinducer
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How is a wound infected with a biofilm treated?
Debridement (cleaning) - frequent and aggressive
Selective biocides - silver, iodosorb, hydrofera blue
Antibiofilm agents - lactoferrin, xylitol, farnesol, plant products, fatty acid gel
Antibiotics - adjunct, strong and long
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Other cards in this set

Card 2

Front

What is a biofilm?

Back

Morphologically heterogenous are multi-layered matrices commonly established by sessile bacteria

Card 3

Front

What happens when environmental conditions change which threatens a mature biofilm?

Back

Preview of the front of card 3

Card 4

Front

What are the applications of biofilms?

Back

Preview of the front of card 4

Card 5

Front

Where can biofilms be found?

Back

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