Quiz 4 - Buxton - Anaerobes Flashcards
What are anaerobes?
Don’t req O2 for life and reproduction
O2’s direct toxic effect may prohibit their growth
Why is O2 toxic?
Reacts with orgo matter. Grabs electrons and produces free radicals
It breaks down or renders useless the small metabolites that become components in cellular systems
O2 combines with the enzymes, proteins, nucleic acids, vitamins, and lipids that are vital to cell reproduction
What are toxic O2 products and free radicals?
O2-
H2O2
OH(dot)
*Lack of protective enzymes, such as superoxide dismutases and peroxidases help explain the toxic effects of O2
**Some anaerobes produce them in varying quantities
T/F - In vivo, bacteria tend to lower the redox potential at their site of growth
TRUE
Mixed colonies provide conditions __________ to the growth of anaerobes.
Favorable
T/F - Volatile and foul-smelling metabolic byproducts of other anaerobes contribute to a balanced environment.
TRUE
What does exogenous mean?
Environmental
What does endogenous mean?
Within
What is an important exogenous anaerobe?
Clostridium - Due to spores
*Though this can be endogenous as well
What sites are notorious for endogenous anaerobes?
Mouth, vagina, bowel, skin
What 5 organisms are found in the oral cavity?
Fusobacterium
Veilonella
Actinomyces
Porphyromonas
Prevotella
What species is found on the skin?
Propionibacterium
What is found in the vagina?
Lactobacillus
Prevotella bivia
What is found in the colon?
Bacteroides fragilis
Bacteroides
What are some factors that lead to anaerobic infections?
Trauma to mucous membranes or skin - trauma allows anaerobes of the indigenous microflora or soil to get access to deeper tissues
Vascular stasis - Stopping of circulation
Tissue necrosis
Decrease of redox potential of tissues
T/F - Anaerobes generally req longer incubation periods in the lab.
TRUE
Look at One Drive for the anaerobes you need to know.
There’s a lot. Look at it jacko
What is the treatment for anaerobic infections?
Create environment where anaerobes cannot proliferate
-Debridement, drainage
Arrest the spread of anaerobes into healthy tissue
-Antimicrobials play an important role here
Neutralize toxins
What are biofilms?
Communities of microorganisms attached to a solid surface.
- Can be a single species
- Important survival mechanisms
- Surface can be non-living or living
What is the inter-species communication system called?
Quorum sensing
-Pheromones
How does a biofilm form?
Attachment of cells to substrate
Growth and aggregation of cells into microcolonies
Maturation and maintenance of architecture
What are the 5 stage of biofilm formation?
Attachment (seconds)
Irreversible binding (minutes)
Layering/Maturation-1
Ultimate thickness/Maturation-2 (days)
Dispersion (several days)
Tell me about attachment.
REVERSIBLE binding
Log growth
Pili and adhesion molecules
Decrease flagella, increase adhesion molecules
Tell me about irreversible binding?
Minutes
Exopolysaccharides trap nutrients and planktonic bacteria
Cells are sessile
Tell me about layering/maturation-1.
Greater than 10 micrometers thick
Tell me about ultimate thickness/maturation-2.
Days
Greater than 100 micrometers thick
Some cells released from substrate, but trapped in the EPS
Tell me about dispersion.
Several days
Cells leaving
Nutrition become scarce, changes in gene expression
Cells again become planktonic
How are biofilms constructed?
Stalks and mushroom-shaped microcolonies attached to the substratum
Matrix contains EPS, proteins, and DNA
-Viable, but not culturable
Fluid-filled channels
- Exchange nutrients
- Dispose of wastes
- Some motile organisms
What are the 3 layers of mature biofilm?
Outer
Intermediate
Innermost
Tell me about the outer biofilm.
Most exposure to nutrients
Most ACTIVE organisms
Some become planktonic
Tell me about the intermediate biofilm.
Metabolism is down-regged, but still using nutrients and exchanging genes
Tell me about the innermost biofilm.
Attached
Earliest and least active
Includes the persister cells
T/F - Biofilms are found in a lot of places. The interplay of biofilm and planktonic phenotypes are 3D architecture are universal.
- Ships
- Rocks
- Sludge
- Lungs of cystic fibrosis pts
- DENTAL PLAQUE
TRUE
What does planktonic mean?
What does sessile mean?
What does persister mean?
Free living
Attached/participating in the biofilm community
Metabolically inert Present in ALL biofilms Potential for maintenance of gene pool Resist stresses, including antibiotics Able to disable apoptosis
What are some advantages to living in a biofilm?
Protection from host defenses
- Protection from O2-reactive molecules
- Physical barrier to PMNs
Potential to outcompete normal biota
Gene transfer
Protective enzymes
Orgo polymers
-Creeping like a lava flow on inanimate surface w/o detachment
T/F - As biofilm forms, streamers of cells extend from the surface and break away to from new biofilms elsewhere.
TRUE
T/F - Disaggregation can transmit already up-regged resistant aggregates of organisms to other body sites.
TRUE
Dental biofilms are called?
Plaque
Bioflims of normal microbiota represent “baseline” organization
How can biofilms reach the heart valves?
Poor hygiene
Blood stream
Heart valves
After teeth cleaning, what happens?
Acquired pellicle
-Proteins and glycopeptides from host
Primary colonizers
- S. Mutans and actinomyces
- Pili and adhesion molecules
- Glycocalyx (Glucan)
Bridge bacteria
- Glucan-binding proteins
- Fusobacterium
- Can’t bind to pellicle, but CAN bind to primary colonizers
Late colonizers
- Strep. Salivarius, propionibacterium/cutibacterium, prevotella, veillonella, selenomonas
- Generally non-pathogenic
With good oral hygiene, what happens to those organisms?
No disease
Balance b/t host and bacterial growth
Mostly gram positive organisms
IF plaque remains, then what?
Microbiota changes
-Anaerobic and facultative G- bacilli and spirochetes
Pathogens -Porphyromonas gingivalis -Bacteroides forsythia -Aggregatibacter actinomycetemcomitans -Treponema denticola *These require the late colonizers in order to attach —Adhere to gingiva —Invade tissue —Initiate an inflammatory response
This causes gingivitis
-Reversible, mild
With really bad hygiene
- Periodontitis
- Loss of teeth
What is sequelae to periodontitis?
Intimate relationship with ulcerated gums
Likely hematogenous spread of adherent bacteria
- Heart valves
- Prosthetic joints
Immune mimicry leading to arthrosclerosis
