Anaerobes and Biofilms Flashcards
Toxic products and free radicals
superoxide, hydrogen peroxide, and hydroxyl radical
Party animals
Sites colonize with mixtures of organisms frequently provide conditions favorable to the growth of anaerobes
-Volatile and foul-smelling metabolic byproducts
Oral anaerobes
- fusbacterium
- veilonella
- actinomyces
- porphyromonas
- prevotella
skin anaerobes
propionibacterium
Vaginal anaerobes
- Lactobacillus
- prevotella bivia
Colon anaerobes
Bacteroides spp.
spore-forming gram pos rods
- c. tetani - tetnaus
- c. perfringenes - gas gangrene
- c. botulinum - botulism
- c. difficile - diarrhea
nonspore-forming gram pos rods
- Actinomyces
- sinus tracts and fistulae
- Sulfur granules - Propionibacterium
- p. acnes, normal skin flora - Mobiluncus
- synergistically with organisms including Gardeneella vaginosis to cause bacterial vaginosis
Gram pos cocci
- peptostreptococcus
- found in abscesses - brain or deep lung - anaerobic and microaerophillic street spp.
- do not respond well to metronidazole
Gram neg cocci
- veillonella spp.
- found in mixed infection of oral origin
Gram neg rods
- bacteroides
- account for 70% of clinically significant anaerobic bacteremia . - Prevotell and porphyromonas
- include former pigmented bacteroides species. common in mouth flora and dental abscess - Fusobacterium
- can also be found with mixed actinomyes spp.
Treatment for anaerobes
- create an environment in which anaerobes cannot proliferate
- arrest the spread of anaerobes into healthy tissue
- neutralize toxins
Stages of biofilm formation
- attachment (sec)
- reversibel binding
- log growth
- pili and bacterial adhesion molecules
- change in gene expression - irreversible binding (min)
- EPS trap nutrients and planktonic bacterio
- cells are sessile - Layering/maturation
- greater than 10 microns thick - ultimate thickness/maturation (days)
- greater than 100 microns thick
- some cells released from substrate, but trapped in EPS - Dispersion (several days)
- cells leaving
- as nutrition becomes scarce, there are changes in gene expression
- cells again become planktonic
Advantages to living in Biofilm
- protection form host defenses
- physical barrier to PMNs/phagocytes
- potetnial to out-compete normal biota
- gene transfer spread resistance in community
- provide protective enzymes
- perform as organic polymers: “creeping”
Primary colonizers
strept mutans and actinomyces
Bridge bacteria
Fusobacterium
-cant bind to pellicle, but can bind to primary colonizers
Late colonizers
strept salvarius, propionibacterium, prevotell, veillonella, selenomonas
Now wondered pathogens
-p. gingivalis
-b. forsythia
-AA
-T. denticola
Require late colonizers in order to attach
